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https://dev.mysql.com/doc/refman/8.4/en/date-and-time-type-conversion.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="date-and-time-type-conversion">
</a>
13.2.8 Conversion Between Date and Time Types
</h3>
</div>
</div>
</div>
<p>
To some extent, you can convert a value from one temporal type
to another. However, there may be some alteration of the value
or loss of information. In all cases, conversion between
temporal types is subject to the range of valid values for the
resulting type. For example, although
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
,
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
, and
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
values all can be
specified using the same set of formats, the types do not all
have the same range of values.
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
values cannot be
earlier than
<code class="literal">
1970
</code>
UTC or later than
<code class="literal">
'2038-01-19 03:14:07'
</code>
UTC. This means that a
date such as
<code class="literal">
'1968-01-01'
</code>
, while valid as a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
value, is not valid as a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
value and is converted
to
<code class="literal">
0
</code>
.
</p>
<p>
Conversion of
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Conversion to a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
value adds a time
part of
<code class="literal">
'00:00:00'
</code>
because the
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
value contains no time
information.
</p>
</li>
<li class="listitem">
<p>
Conversion to a
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
value is
not useful; the result is
<code class="literal">
'00:00:00'
</code>
.
</p>
</li>
</ul>
</div>
<p>
Conversion of
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
and
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Conversion to a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
value
takes fractional seconds into account and rounds the time
part. For example,
<code class="literal">
'1999-12-31
23:59:59.499'
</code>
becomes
<code class="literal">
'1999-12-31'
</code>
, whereas
<code class="literal">
'1999-12-31 23:59:59.500'
</code>
becomes
<code class="literal">
'2000-01-01'
</code>
.
</p>
</li>
<li class="listitem">
<p>
Conversion to a
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
value
discards the date part because the
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
type contains no date
information.
</p>
</li>
</ul>
</div>
<p>
For conversion of
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
values to
other temporal types, the value of
<a class="link" href="date-and-time-functions.html#function_current-date">
<code class="literal">
CURRENT_DATE()
</code>
</a>
is used for the
date part. The
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
is
interpreted as elapsed time (not time of day) and added to the
date. This means that the date part of the result differs from
the current date if the time value is outside the range from
<code class="literal">
'00:00:00'
</code>
to
<code class="literal">
'23:59:59'
</code>
.
</p>
<p>
Suppose that the current date is
<code class="literal">
'2012-01-01'
</code>
.
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
values of
<code class="literal">
'12:00:00'
</code>
,
<code class="literal">
'24:00:00'
</code>
,
and
<code class="literal">
'-12:00:00'
</code>
, when converted to
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
values, result in
<code class="literal">
'2012-01-01 12:00:00'
</code>
,
<code class="literal">
'2012-01-02
00:00:00'
</code>
, and
<code class="literal">
'2011-12-31
12:00:00'
</code>
, respectively.
</p>
<p>
Conversion of
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
to
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
is similar but discards the
time part from the result:
<code class="literal">
'2012-01-01'
</code>
,
<code class="literal">
'2012-01-02'
</code>
, and
<code class="literal">
'2011-12-31'
</code>
, respectively.
</p>
<p>
Explicit conversion can be used to override implicit conversion.
For example, in comparison of
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
and
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
values, the
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
value is coerced to the
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
type by adding a time
part of
<code class="literal">
'00:00:00'
</code>
. To perform the comparison
by ignoring the time part of the
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
value instead, use the
<a class="link" href="cast-functions.html#function_cast">
<code class="literal">
CAST()
</code>
</a>
function in the following
way:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa1966011"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><em class="replaceable">date_col</em> <span class="token operator">=</span> <span class="token function">CAST</span><span class="token punctuation">(</span><em class="replaceable">datetime_col</em> <span class="token keyword">AS</span> <span class="token datatype">DATE</span><span class="token punctuation">)</span></code></pre>
</div>
<p>
Conversion of
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
and
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
values to numeric form
(for example, by adding
<code class="literal">
+0
</code>
) depends on
whether the value contains a fractional seconds part.
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME(
<em class="replaceable">
<code>
N
</code>
</em>
)
</code>
</a>
or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME(
<em class="replaceable">
<code>
N
</code>
</em>
)
</code>
</a>
is converted to integer when
<em class="replaceable">
<code>
N
</code>
</em>
is 0
(or omitted) and to a
<code class="literal">
DECIMAL
</code>
value with
<em class="replaceable">
<code>
N
</code>
</em>
decimal digits when
<em class="replaceable">
<code>
N
</code>
</em>
is greater than 0:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa9203610"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">CURTIME</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">CURTIME</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token function">CURTIME</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">0</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CURTIME() <span class="token punctuation">|</span> CURTIME()<span class="token punctuation">+</span>0 <span class="token punctuation">|</span> CURTIME(3)<span class="token punctuation">+</span>0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 09:28:00 <span class="token punctuation">|</span> 92800 <span class="token punctuation">|</span> 92800.887 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">NOW</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">NOW</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token function">NOW</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">+</span><span class="token number">0</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> NOW() <span class="token punctuation">|</span> NOW()<span class="token punctuation">+</span>0 <span class="token punctuation">|</span> NOW(3)<span class="token punctuation">+</span>0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2012<span class="token punctuation">-</span>08<span class="token punctuation">-</span>15 09:28:00 <span class="token punctuation">|</span> 20120815092800 <span class="token punctuation">|</span> 20120815092800.889 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-mode-change-online.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="replication-mode-change-online">
</a>
19.1.4 Changing GTID Mode on Online Servers
</h3>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="replication-mode-change-online-concepts.html">
19.1.4.1 Replication Mode Concepts
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-mode-change-online-enable-gtids.html">
19.1.4.2 Enabling GTID Transactions Online
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-mode-change-online-disable-gtids.html">
19.1.4.3 Disabling GTID Transactions Online
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-mode-change-online-verify-transactions.html">
19.1.4.4 Verifying Replication of Anonymous Transactions
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045145599360">
</a>
<p>
This section describes how to change the mode of replication from
and to GTID mode without having to take the server offline.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-threadblocks.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-ndbinfo-threadblocks">
</a>
25.6.17.62 The ndbinfo threadblocks Table
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045087578352">
</a>
<p>
The
<code class="literal">
threadblocks
</code>
table associates data nodes,
threads, and instances of
<code class="literal">
NDB
</code>
kernel blocks.
</p>
<p>
The
<code class="literal">
threadblocks
</code>
table contains the following
columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
node_id
</code>
</p>
<p>
Node ID
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
thr_no
</code>
</p>
<p>
Thread ID
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
block_name
</code>
</p>
<p>
Block name
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
block_instance
</code>
</p>
<p>
Block instance number
</p>
</li>
</ul>
</div>
<h5>
<a name="idm46045087565872">
</a>
Notes
</h5>
<p>
The value of the
<code class="literal">
block_name
</code>
in this table is
one of the values found in the
<code class="literal">
block_name
</code>
column when selecting from the
<a class="link" href="mysql-cluster-ndbinfo-blocks.html" title="25.6.17.5 The ndbinfo blocks Table">
<code class="literal">
ndbinfo.blocks
</code>
</a>
table. Although
the list of possible values is static for a given NDB Cluster
release, the list may vary between releases.
</p>
<p>
The
<code class="literal">
block_instance
</code>
column provides the kernel
block instance number.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/windows-start-command-line.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="windows-start-command-line">
</a>
2.3.3.6 Starting MySQL from the Windows Command Line
</h4>
</div>
</div>
</div>
<p>
The MySQL server can be started manually from the command line.
This can be done on any version of Windows.
</p>
<p>
To start the
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
server from the command
line, you should start a console window (or
<span class="quote">
“
<span class="quote">
DOS
window
</span>
”
</span>
) and enter this command:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa81298816"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span> <span class="token atrule">"C:\Program Files\MySQL\MySQL Server 8.4\bin\mysqld"</span></code></pre>
</div>
<p>
The path to
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
may vary depending on the
install location of MySQL on your system.
</p>
<p>
You can stop the MySQL server by executing this command:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa73187633"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span> <span class="token atrule">"C:\Program Files\MySQL\MySQL Server 8.4\bin\mysqladmin"</span> <span class="token property">-u</span> root shutdown</code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
If the MySQL
<code class="literal">
root
</code>
user account has a
password, you need to invoke
<a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program">
<span class="command">
<strong>
mysqladmin
</strong>
</span>
</a>
with the
<code class="option">
-p
</code>
option and supply the password
when prompted.
</p>
</div>
<p>
This command invokes the MySQL administrative utility
<a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program">
<span class="command">
<strong>
mysqladmin
</strong>
</span>
</a>
to connect to the server and tell
it to shut down. The command connects as the MySQL
<code class="literal">
root
</code>
user, which is the default
administrative account in the MySQL grant system.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Users in the MySQL grant system are wholly independent from
any operating system users under Microsoft Windows.
</p>
</div>
<p>
If
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
doesn't start, check the error log
to see whether the server wrote any messages there to indicate
the cause of the problem. By default, the error log is located
in the
<code class="filename">
C:\Program Files\MySQL\MySQL Server
8.4\data
</code>
directory. It is the file with
a suffix of
<code class="filename">
.err
</code>
, or may be specified by
passing in the
<a class="link" href="server-options.html#option_mysqld_log-error">
<code class="option">
--log-error
</code>
</a>
option. Alternatively, you can try to start the server with the
<a class="link" href="server-options.html#option_mysqld_console">
<code class="option">
--console
</code>
</a>
option; in this case,
the server may display some useful information on the screen to
help solve the problem.
</p>
<p>
The last option is to start
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
with the
<a class="link" href="server-options.html#option_mysqld_standalone">
<code class="option">
--standalone
</code>
</a>
and
<a class="link" href="server-options.html#option_mysqld_debug">
<code class="option">
--debug
</code>
</a>
options. In this case,
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
writes a log file
<code class="filename">
C:\mysqld.trace
</code>
that should contain the
reason why
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
doesn't start. See
<a class="xref" href="dbug-package.html" title="7.9.4 The DBUG Package">
Section 7.9.4, “The DBUG Package”
</a>
.
</p>
<p>
Use
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld --verbose --help
</strong>
</span>
</a>
to display all
the options that
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
supports.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-socket-summary-tables.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="performance-schema-socket-summary-tables">
</a>
29.12.20.9 Socket Summary Tables
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045068255632">
</a>
<a class="indexterm" name="idm46045068254128">
</a>
<a class="indexterm" name="idm46045068252624">
</a>
<a class="indexterm" name="idm46045068251120">
</a>
<p>
These socket summary tables aggregate timer and byte count
information for socket operations:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_event_name
</code>
</a>
:
Aggregate timer and byte count statistics generated by the
<code class="literal">
wait/io/socket/*
</code>
instruments for all
socket I/O operations, per socket instrument.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_instance
</code>
</a>
:
Aggregate timer and byte count statistics generated by the
<code class="literal">
wait/io/socket/*
</code>
instruments for all
socket I/O operations, per socket instance. When a
connection terminates, the row in
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_instance
</code>
</a>
corresponding to it is deleted.
</p>
</li>
</ul>
</div>
<p>
The socket summary tables do not aggregate waits generated by
<code class="literal">
idle
</code>
events while sockets are waiting for
the next request from the client. For
<code class="literal">
idle
</code>
event aggregations, use the wait-event summary tables; see
<a class="xref" href="performance-schema-wait-summary-tables.html" title="29.12.20.1 Wait Event Summary Tables">
Section 29.12.20.1, “Wait Event Summary Tables”
</a>
.
</p>
<p>
Each socket summary table has one or more grouping columns to
indicate how the table aggregates events. Event names refer to
names of event instruments in the
<a class="link" href="performance-schema-setup-instruments-table.html" title="29.12.2.3 The setup_instruments Table">
<code class="literal">
setup_instruments
</code>
</a>
table:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_event_name
</code>
</a>
has an
<code class="literal">
EVENT_NAME
</code>
column. Each row
summarizes events for a given event name.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_instance
</code>
</a>
has an
<code class="literal">
OBJECT_INSTANCE_BEGIN
</code>
column.
Each row summarizes events for a given object.
</p>
</li>
</ul>
</div>
<p>
Each socket summary table has these summary columns containing
aggregated values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
COUNT_STAR
</code>
,
<code class="literal">
SUM_TIMER_WAIT
</code>
,
<code class="literal">
MIN_TIMER_WAIT
</code>
,
<code class="literal">
AVG_TIMER_WAIT
</code>
,
<code class="literal">
MAX_TIMER_WAIT
</code>
</p>
<p>
These columns aggregate all operations.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
COUNT_READ
</code>
,
<code class="literal">
SUM_TIMER_READ
</code>
,
<code class="literal">
MIN_TIMER_READ
</code>
,
<code class="literal">
AVG_TIMER_READ
</code>
,
<code class="literal">
MAX_TIMER_READ
</code>
,
<code class="literal">
SUM_NUMBER_OF_BYTES_READ
</code>
</p>
<p>
These columns aggregate all receive operations
(
<code class="literal">
RECV
</code>
,
<code class="literal">
RECVFROM
</code>
, and
<code class="literal">
RECVMSG
</code>
).
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
COUNT_WRITE
</code>
,
<code class="literal">
SUM_TIMER_WRITE
</code>
,
<code class="literal">
MIN_TIMER_WRITE
</code>
,
<code class="literal">
AVG_TIMER_WRITE
</code>
,
<code class="literal">
MAX_TIMER_WRITE
</code>
,
<code class="literal">
SUM_NUMBER_OF_BYTES_WRITE
</code>
</p>
<p>
These columns aggregate all send operations
(
<code class="literal">
SEND
</code>
,
<code class="literal">
SENDTO
</code>
, and
<code class="literal">
SENDMSG
</code>
).
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
COUNT_MISC
</code>
,
<code class="literal">
SUM_TIMER_MISC
</code>
,
<code class="literal">
MIN_TIMER_MISC
</code>
,
<code class="literal">
AVG_TIMER_MISC
</code>
,
<code class="literal">
MAX_TIMER_MISC
</code>
</p>
<p>
These columns aggregate all other socket operations, such
as
<code class="literal">
CONNECT
</code>
,
<code class="literal">
LISTEN
</code>
,
<code class="literal">
ACCEPT
</code>
,
<code class="literal">
CLOSE
</code>
, and
<code class="literal">
SHUTDOWN
</code>
. There are no byte counts for
these operations.
</p>
</li>
</ul>
</div>
<p>
The
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_instance
</code>
</a>
table also has an
<code class="literal">
EVENT_NAME
</code>
column that
indicates the class of the socket:
<code class="literal">
client_connection
</code>
,
<code class="literal">
server_tcpip_socket
</code>
,
<code class="literal">
server_unix_socket
</code>
. This column can be
grouped on to isolate, for example, client activity from that
of the server listening sockets.
</p>
<p>
The socket summary tables have these indexes:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_event_name
</code>
</a>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Primary key on (
<code class="literal">
EVENT_NAME
</code>
)
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
<a class="link" href="performance-schema-socket-summary-tables.html" title="29.12.20.9 Socket Summary Tables">
<code class="literal">
socket_summary_by_instance
</code>
</a>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Primary key on
(
<code class="literal">
OBJECT_INSTANCE_BEGIN
</code>
)
</p>
</li>
<li class="listitem">
<p>
Index on (
<code class="literal">
EVENT_NAME
</code>
)
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
<a class="link" href="truncate-table.html" title="15.1.37 TRUNCATE TABLE Statement">
<code class="literal">
TRUNCATE TABLE
</code>
</a>
is permitted for
socket summary tables. Except for
<a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables">
<code class="literal">
events_statements_summary_by_digest
</code>
</a>
,
it resets the summary columns to zero rather than removing
rows.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/invisible-columns.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="invisible-columns">
</a>
15.1.20.10 Invisible Columns
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045184610736">
</a>
<p>
MySQL 8.4 supports invisible columns. An invisible
column is normally hidden to queries, but can be accessed if
explicitly referenced.
</p>
<p>
As an illustration of when invisible columns may be useful,
suppose that an application uses
<code class="literal">
SELECT *
</code>
queries to access a table, and must continue to work without
modification even if the table is altered to add a new column
that the application does not expect to be there. In a
<code class="literal">
SELECT *
</code>
query, the
<code class="literal">
*
</code>
evaluates to all table columns, except those that are invisible,
so the solution is to add the new column as an invisible column.
The column remains
<span class="quote">
“
<span class="quote">
hidden
</span>
”
</span>
from
<code class="literal">
SELECT
*
</code>
queries, and the application continues to work as
previously. A newer version of the application can refer to the
invisible column if necessary by explicitly referencing it.
</p>
<p>
The following sections detail how MySQL treats invisible
columns.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="invisible-columns.html#invisible-column-ddl-statements" title="DDL Statements and Invisible Columns">
DDL Statements and Invisible Columns
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="invisible-columns.html#invisible-column-dml-statements" title="DML Statements and Invisible Columns">
DML Statements and Invisible Columns
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="invisible-columns.html#invisible-column-metadata" title="Invisible Column Metadata">
Invisible Column Metadata
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="invisible-columns.html#invisible-column-binary-logging" title="The Binary Log and Invisible Columns">
The Binary Log and Invisible Columns
</a>
</p>
</li>
</ul>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="invisible-column-ddl-statements">
</a>
DDL Statements and Invisible Columns
</h5>
</div>
</div>
</div>
<p>
Columns are visible by default. To explicitly specify
visibility for a new column, use a
<code class="literal">
VISIBLE
</code>
or
<code class="literal">
INVISIBLE
</code>
keyword as part of the column
definition for
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92909814"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
i <span class="token datatype">INT</span><span class="token punctuation">,</span>
j <span class="token datatype">DATE</span> <span class="token keyword">INVISIBLE</span>
<span class="token punctuation">)</span> <span class="token keyword">ENGINE</span> <span class="token operator">=</span> InnoDB<span class="token punctuation">;</span>
<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">COLUMN</span> k <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
To alter the visibility of an existing column, use a
<code class="literal">
VISIBLE
</code>
or
<code class="literal">
INVISIBLE
</code>
keyword with one of the
<code class="literal">
ALTER TABLE
</code>
column-modification clauses:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa19956830"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">CHANGE</span> <span class="token keyword">COLUMN</span> j j <span class="token datatype">DATE</span> <span class="token keyword">VISIBLE</span><span class="token punctuation">;</span>
<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">MODIFY</span> <span class="token keyword">COLUMN</span> j <span class="token datatype">DATE</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">;</span>
<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ALTER</span> <span class="token keyword">COLUMN</span> j <span class="token keyword">SET</span> <span class="token keyword">VISIBLE</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
A table must have at least one visible column. Attempting to
make all columns invisible produces an error.
</p>
<p>
Invisible columns support the usual column attributes:
<code class="literal">
NULL
</code>
,
<code class="literal">
NOT NULL
</code>
,
<code class="literal">
AUTO_INCREMENT
</code>
, and so forth.
</p>
<p>
Generated columns can be invisible.
</p>
<p>
Index definitions can name invisible columns, including
definitions for
<code class="literal">
PRIMARY KEY
</code>
and
<code class="literal">
UNIQUE
</code>
indexes. Although a table must have
at least one visible column, an index definition need not have
any visible columns.
</p>
<p>
An invisible column dropped from a table is dropped in the
usual way from any index definition that names the column.
</p>
<p>
Foreign key constraints can be defined on invisible columns,
and foreign key constraints can reference invisible columns.
</p>
<p>
<code class="literal">
CHECK
</code>
constraints can be defined on
invisible columns. For new or modified rows, violation of a
<code class="literal">
CHECK
</code>
constraint on an invisible column
produces an error.
</p>
<p>
<a class="link" href="create-table-like.html" title="15.1.20.3 CREATE TABLE ... LIKE Statement">
<code class="literal">
CREATE
TABLE ... LIKE
</code>
</a>
includes invisible columns, and they
are invisible in the new table.
</p>
<p>
<a class="link" href="create-table-select.html" title="15.1.20.4 CREATE TABLE ... SELECT Statement">
<code class="literal">
CREATE
TABLE ... SELECT
</code>
</a>
does not include invisible columns,
unless they are explicitly referenced in the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part. However, even if
explicitly referenced, a column that is invisible in the
existing table is visible in the new table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa44145903"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>col1 <span class="token datatype">INT</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> col2 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> t2
Create Table<span class="token punctuation">:</span> CREATE TABLE `t2` (
`col1` int DEFAULT NULL,
`col2` int DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci</span></code></pre>
</div>
<p>
If invisibility should be preserved, provide a definition for
the invisible column in the
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE
TABLE
</code>
</a>
part of the
<a class="link" href="create-table-select.html" title="15.1.20.4 CREATE TABLE ... SELECT Statement">
<code class="literal">
CREATE
TABLE ... SELECT
</code>
</a>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa90850421"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>col1 <span class="token datatype">INT</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span>col2 <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> col2 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> t2
Create Table<span class="token punctuation">:</span> CREATE TABLE `t2` (
`col1` int DEFAULT NULL,
`col2` int DEFAULT NULL /<span class="token punctuation">*</span>!80023 INVISIBLE <span class="token punctuation">*</span>/
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci</span></code></pre>
</div>
<p>
Views can refer to invisible columns by explicitly referencing
them in the
<code class="literal">
SELECT
</code>
statement that defines
the view. Changing a column's visibility subsequent to
defining a view that references the column does not change
view behavior.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="invisible-column-dml-statements">
</a>
DML Statements and Invisible Columns
</h5>
</div>
</div>
</div>
<p>
For
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements, an
invisible column is not part of the result set unless
explicitly referenced in the select list. In a select list,
the
<code class="literal">
*
</code>
and
<code class="literal">
<em class="replaceable">
<code>
tbl_name
</code>
</em>
.*
</code>
shorthands do not include invisible columns. Natural joins do
not include invisible columns.
</p>
<p>
Consider the following statement sequence:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86642639"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>col1 <span class="token datatype">INT</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> col1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> col2 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> col1 <span class="token punctuation">|</span> col2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The first
<code class="literal">
SELECT
</code>
does not reference the
invisible column
<code class="literal">
col2
</code>
in the select list
(because
<code class="literal">
*
</code>
does not include invisible
columns), so
<code class="literal">
col2
</code>
does not appear in the
statement result. The second
<code class="literal">
SELECT
</code>
explicitly references
<code class="literal">
col2
</code>
, so the column
appears in the result.
</p>
<p>
The statement
<a class="link" href="table.html" title="15.2.16 TABLE Statement">
<code class="literal">
TABLE
t1
</code>
</a>
produces the same output as the first
<code class="literal">
SELECT
</code>
statement. Since there is no way to
specify columns in a
<code class="literal">
TABLE
</code>
statement,
<code class="literal">
TABLE
</code>
never displays invisible columns.
</p>
<p>
For statements that create new rows, an invisible column is
assigned its implicit default value unless explicitly
referenced and assigned a value. For information about
implicit defaults, see
<a class="xref" href="data-type-defaults.html#data-type-defaults-implicit" title="Implicit Default Handling">
Implicit Default Handling
</a>
.
</p>
<p>
For
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
(and
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
, for non-replaced
rows), implicit default assignment occurs with a missing
column list, an empty column list, or a nonempty column list
that does not include the invisible column:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa44515554"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>col1 <span class="token datatype">INT</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token keyword">INVISIBLE</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>col1<span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
For the first two
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements, the
<code class="literal">
VALUES()
</code>
list must provide
a value for each visible column and no invisible column. For
the third
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement, the
<code class="literal">
VALUES()
</code>
list must provide the same number
of values as the number of named columns; the same is true
when you use
<a class="link" href="values.html" title="15.2.19 VALUES Statement">
<code class="literal">
VALUES
ROW()
</code>
</a>
rather than
<code class="literal">
VALUES()
</code>
.
</p>
<p>
For
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
and
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
, implicit default
assignment occurs with a missing column list or a nonempty
column list that does not include the invisible column. Input
rows should not include a value for the invisible column.
</p>
<p>
To assign a value other than the implicit default for the
preceding statements, explicitly name the invisible column in
the column list and provide a value for it.
</p>
<p>
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT INTO ...
SELECT *
</code>
</a>
and
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE INTO ...
SELECT *
</code>
</a>
do not include invisible columns because
<code class="literal">
*
</code>
does not include invisible columns.
Implicit default assignment occurs as described previously.
</p>
<p>
For statements that insert or ignore new rows, or that replace
or modify existing rows, based on values in a
<code class="literal">
PRIMARY
KEY
</code>
or
<code class="literal">
UNIQUE
</code>
index, MySQL treats
invisible columns the same as visible columns: Invisible
columns participate in key value comparisons. Specifically, if
a new row has the same value as an existing row for a unique
key value, these behaviors occur whether the index columns are
visible or invisible:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
With the
<code class="literal">
IGNORE
</code>
modifier,
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
, and
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
ignore the new
row.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
replaces the
existing row with the new row. With the
<code class="literal">
REPLACE
</code>
modifier,
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
and
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
do the same.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="insert-on-duplicate.html" title="15.2.7.2 INSERT ... ON DUPLICATE KEY UPDATE Statement">
<code class="literal">
INSERT
... ON DUPLICATE KEY UPDATE
</code>
</a>
updates the existing
row.
</p>
</li>
</ul>
</div>
<p>
To update invisible columns for
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statements, name them
and assign a value, just as for visible columns.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="invisible-column-metadata">
</a>
Invisible Column Metadata
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045184508656">
</a>
<a class="indexterm" name="idm46045184507168">
</a>
<p>
Information about whether a column is visible or invisible is
available from the
<code class="literal">
EXTRA
</code>
column of the
Information Schema
<a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table">
<code class="literal">
COLUMNS
</code>
</a>
table
or
<a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement">
<code class="literal">
SHOW COLUMNS
</code>
</a>
output. For
example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa9353432"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token keyword">COLUMN_NAME</span><span class="token punctuation">,</span> EXTRA
<span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span><span class="token keyword">COLUMNS</span>
<span class="token keyword">WHERE</span> TABLE_SCHEMA <span class="token operator">=</span> <span class="token string">'test'</span> <span class="token operator">AND</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">=</span> <span class="token string">'t1'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> TABLE_NAME <span class="token punctuation">|</span> COLUMN_NAME <span class="token punctuation">|</span> EXTRA <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> t1 <span class="token punctuation">|</span> i <span class="token punctuation">|</span> <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t1 <span class="token punctuation">|</span> j <span class="token punctuation">|</span> <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> t1 <span class="token punctuation">|</span> k <span class="token punctuation">|</span> INVISIBLE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
Columns are visible by default, so in that case,
<code class="literal">
EXTRA
</code>
displays no visibility information.
For invisible columns,
<code class="literal">
EXTRA
</code>
displays
<code class="literal">
INVISIBLE
</code>
.
</p>
<p>
<code class="literal">
SHOW CREATE TABLE
</code>
displays invisible
columns in the table definition, with the
<code class="literal">
INVISIBLE
</code>
keyword in a version-specific
comment:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69592236"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> t1
Create Table<span class="token punctuation">:</span> CREATE TABLE `t1` (
`i` int DEFAULT NULL,
`j` int DEFAULT NULL,
`k` int DEFAULT NULL /<span class="token punctuation">*</span>!80023 INVISIBLE <span class="token punctuation">*</span>/
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci</span></code></pre>
</div>
<p>
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
uses
<code class="literal">
SHOW CREATE
TABLE
</code>
, so they include invisible columns in dumped
table definitions. They also include invisible column values
in dumped data.
</p>
<p>
Reloading a dump file into an older version of MySQL that does
not support invisible columns causes the version-specific
comment to be ignored, which creates any invisible columns as
visible.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="invisible-column-binary-logging">
</a>
The Binary Log and Invisible Columns
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045184487632">
</a>
<a class="indexterm" name="idm46045184486144">
</a>
<p>
MySQL treats invisible columns as follows with respect to
events in the binary log:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Table-creation events include the
<code class="literal">
INVISIBLE
</code>
attribute for invisible
columns.
</p>
</li>
<li class="listitem">
<p>
Invisible columns are treated like visible columns in row
events. They are included if needed according to the
<a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_image">
<code class="literal">
binlog_row_image
</code>
</a>
system
variable setting.
</p>
</li>
<li class="listitem">
<p>
When row events are applied, invisible columns are treated
like visible columns in row events.
</p>
</li>
<li class="listitem">
<p>
Invisible columns are treated like visible columns when
computing writesets. In particular, writesets include
indexes defined on invisible columns.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files">
<span class="command">
<strong>
mysqlbinlog
</strong>
</span>
</a>
command includes
visibility in column metadata.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-limits.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="innodb-limits">
</a>
17.21 InnoDB Limits
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045148828400">
</a>
<a class="indexterm" name="idm46045148826912">
</a>
<p>
This section describes limits for
<code class="literal">
InnoDB
</code>
tables, indexes, tablespaces, and other aspects of the
<code class="literal">
InnoDB
</code>
storage engine.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
A table can contain a maximum of 1017 columns. Virtual
generated columns are included in this limit.
</p>
</li>
<li class="listitem">
<p>
A table can contain a maximum of 64
<a class="link" href="glossary.html#glos_secondary_index" title="secondary index">
secondary indexes
</a>
.
</p>
</li>
<li class="listitem">
<p>
The index key prefix length limit is 3072 bytes for
<code class="literal">
InnoDB
</code>
tables that use
<code class="literal">
<a class="link" href="glossary.html#glos_dynamic_row_format" title="dynamic row format">
DYNAMIC
</a>
</code>
or
<code class="literal">
<a class="link" href="glossary.html#glos_compressed_row_format" title="compressed row format">
COMPRESSED
</a>
</code>
row format.
</p>
<p>
The index key prefix length limit is 767 bytes for
<code class="literal">
InnoDB
</code>
tables that use the
<code class="literal">
<a class="link" href="glossary.html#glos_redundant_row_format" title="redundant row format">
REDUNDANT
</a>
</code>
or
<code class="literal">
<a class="link" href="glossary.html#glos_compact_row_format" title="compact row format">
COMPACT
</a>
</code>
row format. For example, you might hit this limit with a
<a class="link" href="glossary.html#glos_column_prefix" title="column prefix">
column prefix
</a>
index
of more than 191 characters on a
<code class="literal">
TEXT
</code>
or
<code class="literal">
VARCHAR
</code>
column, assuming a
<code class="literal">
utf8mb4
</code>
character set and the maximum of 4
bytes for each character.
</p>
<p>
Attempting to use an index key prefix length that exceeds the
limit returns an error.
</p>
<p>
If you reduce the
<code class="literal">
InnoDB
</code>
<a class="link" href="glossary.html#glos_page_size" title="page size">
page size
</a>
to 8KB or 4KB
by specifying the
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
option when
creating the MySQL instance, the maximum length of the index
key is lowered proportionally, based on the limit of 3072
bytes for a 16KB page size. That is, the maximum index key
length is 1536 bytes when the page size is 8KB, and 768 bytes
when the page size is 4KB.
</p>
<p>
The limits that apply to index key prefixes also apply to
full-column index keys.
</p>
</li>
<li class="listitem">
<p>
A maximum of 16 columns is permitted for multicolumn indexes.
Exceeding the limit returns an error.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa15821070"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token output">ERROR 1070 (42000)<span class="token punctuation">:</span> Too many key parts specified; max 16 parts allowed</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
The maximum row size, excluding any variable-length columns
that are stored off-page, is slightly less than half of a page
for 4KB, 8KB, 16KB, and 32KB page sizes. For example, the
maximum row size for the default
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
of 16KB is
about 8000 bytes. However, for an
<code class="literal">
InnoDB
</code>
page size of 64KB, the maximum row size is approximately 16000
bytes.
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
LONGBLOB
</code>
</a>
and
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
LONGTEXT
</code>
</a>
columns must be less than 4GB, and the total row size,
including
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
BLOB
</code>
</a>
and
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
TEXT
</code>
</a>
columns, must be less than
4GB.
</p>
<p>
If a row is less than half a page long, all of it is stored
locally within the page. If it exceeds half a page,
variable-length columns are chosen for external off-page
storage until the row fits within half a page, as described in
<a class="xref" href="innodb-file-space.html" title="17.11.2 File Space Management">
Section 17.11.2, “File Space Management”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Although
<code class="literal">
InnoDB
</code>
supports row sizes larger
than 65,535 bytes internally, MySQL itself imposes a row-size
limit of 65,535 for the combined size of all columns. See
<a class="xref" href="column-count-limit.html" title="10.4.7 Limits on Table Column Count and Row Size">
Section 10.4.7, “Limits on Table Column Count and Row Size”
</a>
.
</p>
</li>
<li class="listitem">
<p>
The maximum table or tablespace size is impacted by the
server's file system, which can impose a maximum file
size that is smaller than the internal 64 TiB size limit
defined by
<code class="literal">
InnoDB
</code>
. For example, the
<span class="emphasis">
<em>
ext4
</em>
</span>
file system on Linux has a maximum
file size of 16 TiB, so the maximum table or tablespace size
becomes 16 TiB instead of 64 TiB. Another example is the
<span class="emphasis">
<em>
FAT32
</em>
</span>
file system, which has a maximum
file size of 4 GB.
</p>
<p>
If you require a larger system tablespace, configure it using
several smaller data files rather than one large data file, or
distribute table data across file-per-table and general
tablespace data files.
</p>
</li>
<li class="listitem">
<p>
The combined maximum size for
<code class="literal">
InnoDB
</code>
log
files is 512GB.
</p>
</li>
<li class="listitem">
<p>
The minimum tablespace size is slightly larger than 10MB. The
maximum tablespace size depends on the
<code class="literal">
InnoDB
</code>
page size.
</p>
<div class="table">
<a name="idm46045148784528">
</a>
<p class="title">
<b>
Table 17.26 InnoDB Maximum Tablespace Size
</b>
</p>
<div class="table-contents">
<table summary="The maximum tablespace size for each InnoDB page size.">
<colgroup>
<col style="width: 40%"/>
<col style="width: 60%"/>
</colgroup>
<thead>
<tr>
<th>
InnoDB Page Size
</th>
<th>
Maximum Tablespace Size
</th>
</tr>
</thead>
<tbody>
<tr>
<td>
4KB
</td>
<td>
16TB
</td>
</tr>
<tr>
<td>
8KB
</td>
<td>
32TB
</td>
</tr>
<tr>
<td>
16KB
</td>
<td>
64TB
</td>
</tr>
<tr>
<td>
32KB
</td>
<td>
128TB
</td>
</tr>
<tr>
<td>
64KB
</td>
<td>
256TB
</td>
</tr>
</tbody>
</table>
</div>
</div>
<br class="table-break"/>
<p>
The maximum tablespace size is also the maximum size for a
table.
</p>
</li>
<li class="listitem">
<p>
An
<code class="literal">
InnoDB
</code>
instance supports up to 2^32
(4294967296) tablespaces, with a small number of those
tablespaces reserved for undo and temporary tables.
</p>
</li>
<li class="listitem">
<p>
Shared tablespaces support up to 2^32 (4294967296) tables.
</p>
</li>
<li class="listitem">
<p>
The path of a tablespace file, including the file name, cannot
exceed the
<code class="literal">
MAX_PATH
</code>
limit on Windows. Prior
to Windows 10, the
<code class="literal">
MAX_PATH
</code>
limit is 260
characters. As of Windows 10, version 1607,
<code class="literal">
MAX_PATH
</code>
limitations are removed from
common Win32 file and directory functions, but you must enable
the new behavior.
</p>
</li>
<li class="listitem">
<p>
For limits associated with concurrent read-write transactions,
see
<a class="xref" href="innodb-undo-logs.html" title="17.6.6 Undo Logs">
Section 17.6.6, “Undo Logs”
</a>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-information-schema-buffer-pool-tables.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="innodb-information-schema-buffer-pool-tables">
</a>
17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables
</h3>
</div>
</div>
</div>
<p>
The
<code class="literal">
InnoDB
</code>
<code class="literal">
INFORMATION_SCHEMA
</code>
buffer pool tables provide
buffer pool status information and metadata about the pages within
the
<code class="literal">
InnoDB
</code>
buffer pool.
</p>
<p>
The
<code class="literal">
InnoDB
</code>
<code class="literal">
INFORMATION_SCHEMA
</code>
buffer pool tables include
those listed below:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72575031"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">TABLES</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA <span class="token operator">LIKE</span> <span class="token string">'INNODB_BUFFER%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Tables_in_INFORMATION_SCHEMA (INNODB_BUFFER%) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> INNODB_BUFFER_PAGE_LRU <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> INNODB_BUFFER_PAGE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> INNODB_BUFFER_POOL_STATS <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<h4>
<a name="idm46045150065712">
</a>
Table Overview
</h4>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table">
<code class="literal">
INNODB_BUFFER_PAGE
</code>
</a>
: Holds
information about each page in the
<code class="literal">
InnoDB
</code>
buffer pool.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
: Holds
information about the pages in the
<code class="literal">
InnoDB
</code>
buffer pool, in particular how they are ordered in the LRU
list that determines which pages to evict from the buffer pool
when it becomes full. The
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
table has
the same columns as the
<a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table">
<code class="literal">
INNODB_BUFFER_PAGE
</code>
</a>
table, except
that the
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
table has an
<code class="literal">
LRU_POSITION
</code>
column instead of
a
<code class="literal">
BLOCK_ID
</code>
column.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table">
<code class="literal">
INNODB_BUFFER_POOL_STATS
</code>
</a>
:
Provides buffer pool status information. Much of the same
information is provided by
<a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement">
<code class="literal">
SHOW ENGINE
INNODB STATUS
</code>
</a>
output, or may be obtained using
<code class="literal">
InnoDB
</code>
buffer pool server status variables.
</p>
</li>
</ul>
</div>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
Querying the
<a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table">
<code class="literal">
INNODB_BUFFER_PAGE
</code>
</a>
or
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
table can
affect performance. Do not query these tables on a production
system unless you are aware of the performance impact and have
determined it to be acceptable. To avoid impacting performance
on a production system, reproduce the issue you want to
investigate and query buffer pool statistics on a test instance.
</p>
</div>
<div class="example">
<a name="innodb-information-schema-buffer-pool-system-data-example">
</a>
<p class="title">
<b>
Example 17.6 Querying System Data in the INNODB_BUFFER_PAGE Table
</b>
</p>
<div class="example-contents">
<p>
This query provides an approximate count of pages that contain
system data by excluding pages where the
<code class="literal">
TABLE_NAME
</code>
value is either
<code class="literal">
NULL
</code>
or includes a slash
<code class="literal">
/
</code>
or period
<code class="literal">
.
</code>
in the table name, which
indicates a user-defined table.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5319516"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token boolean">NULL</span> <span class="token operator">OR</span> <span class="token punctuation">(</span><span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'/'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span> <span class="token operator">AND</span> <span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'.'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> COUNT(*) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1516 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This query returns the approximate number of pages that contain
system data, the total number of buffer pool pages, and an
approximate percentage of pages that contain system data.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa54654149"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span>
<span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token boolean">NULL</span> <span class="token operator">OR</span> <span class="token punctuation">(</span><span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'/'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span> <span class="token operator">AND</span> <span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'.'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">AS</span> system_pages<span class="token punctuation">,</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span>
<span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token punctuation">)</span> <span class="token keyword">AS</span> total_pages<span class="token punctuation">,</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token punctuation">(</span>system_pages<span class="token operator">/</span>total_pages<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">100</span><span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">AS</span> system_page_percentage<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> system_pages <span class="token punctuation">|</span> total_pages <span class="token punctuation">|</span> system_page_percentage <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 295 <span class="token punctuation">|</span> 8192 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The type of system data in the buffer pool can be determined by
querying the
<code class="literal">
PAGE_TYPE
</code>
value. For example,
the following query returns eight distinct
<code class="literal">
PAGE_TYPE
</code>
values among the pages that contain
system data:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa71329501"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">DISTINCT</span> PAGE_TYPE <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token boolean">NULL</span> <span class="token operator">OR</span> <span class="token punctuation">(</span><span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'/'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span> <span class="token operator">AND</span> <span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'.'</span><span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> PAGE_TYPE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> SYSTEM <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> IBUF_BITMAP <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> UNKNOWN <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> FILE_SPACE_HEADER <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> INODE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> UNDO_LOG <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> ALLOCATED <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br class="example-break"/>
<div class="example">
<a name="innodb-information-schema-buffer-pool-user-data-example">
</a>
<p class="title">
<b>
Example 17.7 Querying User Data in the INNODB_BUFFER_PAGE Table
</b>
</p>
<div class="example-contents">
<p>
This query provides an approximate count of pages containing
user data by counting pages where the
<code class="literal">
TABLE_NAME
</code>
value is
<code class="literal">
NOT
NULL
</code>
and
<code class="literal">
NOT LIKE
'%INNODB_TABLES%'
</code>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa43193559"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token operator">AND</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">NOT</span> <span class="token operator">LIKE</span> <span class="token string">'%INNODB_TABLES%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> COUNT(*) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 7897 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This query returns the approximate number of pages that contain
user data, the total number of buffer pool pages, and an
approximate percentage of pages that contain user data.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa1856040"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span>
<span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token operator">AND</span> <span class="token punctuation">(</span><span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'/'</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">OR</span> <span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'.'</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">AS</span> user_pages<span class="token punctuation">,</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span>
<span class="token keyword">FROM</span> information_schema<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token punctuation">)</span> <span class="token keyword">AS</span> total_pages<span class="token punctuation">,</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token punctuation">(</span>user_pages<span class="token operator">/</span>total_pages<span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">100</span><span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">AS</span> user_page_percentage<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> user_pages <span class="token punctuation">|</span> total_pages <span class="token punctuation">|</span> user_page_percentage <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 7897 <span class="token punctuation">|</span> 8192 <span class="token punctuation">|</span> 96 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This query identifies user-defined tables with pages in the
buffer pool:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa95267780"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">DISTINCT</span> <span class="token keyword">TABLE_NAME</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">IS</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token operator">AND</span> <span class="token punctuation">(</span><span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'/'</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">0</span> <span class="token operator">OR</span> <span class="token function">INSTR</span><span class="token punctuation">(</span><span class="token keyword">TABLE_NAME</span><span class="token punctuation">,</span> <span class="token string">'.'</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token operator">AND</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">NOT</span> <span class="token operator">LIKE</span> <span class="token string">'`mysql`.`innodb_%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> TABLE_NAME <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> `employees`.`salaries` <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> `employees`.`employees` <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br class="example-break"/>
<div class="example">
<a name="innodb-information-schema-buffer-pool-index-data-example">
</a>
<p class="title">
<b>
Example 17.8 Querying Index Data in the INNODB_BUFFER_PAGE Table
</b>
</p>
<div class="example-contents">
<p>
For information about index pages, query the
<code class="literal">
INDEX_NAME
</code>
column using the name of the
index. For example, the following query returns the number of
pages and total data size of pages for the
<code class="literal">
emp_no
</code>
index that is defined on the
<code class="literal">
employees.salaries
</code>
table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67719476"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> INDEX_NAME<span class="token punctuation">,</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> Pages<span class="token punctuation">,</span>
<span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">SUM</span><span class="token punctuation">(</span><span class="token function">IF</span><span class="token punctuation">(</span>COMPRESSED_SIZE <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token variable">@@GLOBAL.innodb_page_size</span><span class="token punctuation">,</span> COMPRESSED_SIZE<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token operator">/</span><span class="token number">1024</span><span class="token operator">/</span><span class="token number">1024</span><span class="token punctuation">)</span>
<span class="token keyword">AS</span> <span class="token string">'Total Data (MB)'</span>
<span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> INDEX_NAME<span class="token operator">=</span><span class="token string">'emp_no'</span> <span class="token operator">AND</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">=</span> <span class="token string">'`employees`.`salaries`'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> INDEX_NAME <span class="token punctuation">|</span> Pages <span class="token punctuation">|</span> Total Data (MB) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> emp_no <span class="token punctuation">|</span> 1609 <span class="token punctuation">|</span> 25 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This query returns the number of pages and total data size of
pages for all indexes defined on the
<code class="literal">
employees.salaries
</code>
table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24141961"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> INDEX_NAME<span class="token punctuation">,</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> Pages<span class="token punctuation">,</span>
<span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">SUM</span><span class="token punctuation">(</span><span class="token function">IF</span><span class="token punctuation">(</span>COMPRESSED_SIZE <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token variable">@@GLOBAL.innodb_page_size</span><span class="token punctuation">,</span> COMPRESSED_SIZE<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token operator">/</span><span class="token number">1024</span><span class="token operator">/</span><span class="token number">1024</span><span class="token punctuation">)</span>
<span class="token keyword">AS</span> <span class="token string">'Total Data (MB)'</span>
<span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span> <span class="token operator">=</span> <span class="token string">'`employees`.`salaries`'</span>
<span class="token keyword">GROUP</span> <span class="token keyword">BY</span> INDEX_NAME<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> INDEX_NAME <span class="token punctuation">|</span> Pages <span class="token punctuation">|</span> Total Data (MB) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> emp_no <span class="token punctuation">|</span> 1608 <span class="token punctuation">|</span> 25 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> PRIMARY <span class="token punctuation">|</span> 6086 <span class="token punctuation">|</span> 95 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br class="example-break"/>
<div class="example">
<a name="innodb-information-schema-buffer-pool-lru-position-example">
</a>
<p class="title">
<b>
Example 17.9 Querying LRU_POSITION Data in the INNODB_BUFFER_PAGE_LRU Table
</b>
</p>
<div class="example-contents">
<p>
The
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
table
holds information about the pages in the
<code class="literal">
InnoDB
</code>
buffer pool, in particular how they
are ordered that determines which pages to evict from the buffer
pool when it becomes full. The definition for this page is the
same as for
<a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table">
<code class="literal">
INNODB_BUFFER_PAGE
</code>
</a>
,
except this table has an
<code class="literal">
LRU_POSITION
</code>
column
instead of a
<code class="literal">
BLOCK_ID
</code>
column.
</p>
<p>
This query counts the number of positions at a specific location
in the LRU list occupied by pages of the
<code class="literal">
employees.employees
</code>
table.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa17276916"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span>LRU_POSITION<span class="token punctuation">)</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_BUFFER_PAGE_LRU
<span class="token keyword">WHERE</span> <span class="token keyword">TABLE_NAME</span><span class="token operator">=</span><span class="token string">'`employees`.`employees`'</span> <span class="token operator">AND</span> LRU_POSITION <span class="token operator"><</span> <span class="token number">3072</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> COUNT(LRU_POSITION) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 548 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br class="example-break"/>
<div class="example">
<a name="innodb-information-schema-buffer-pool-stats-example">
</a>
<p class="title">
<b>
Example 17.10 Querying the INNODB_BUFFER_POOL_STATS Table
</b>
</p>
<div class="example-contents">
<p>
The
<a class="link" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table">
<code class="literal">
INNODB_BUFFER_POOL_STATS
</code>
</a>
table
provides information similar to
<a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement">
<code class="literal">
SHOW ENGINE INNODB
STATUS
</code>
</a>
and
<code class="literal">
InnoDB
</code>
buffer pool
status variables.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47349852"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> information_schema<span class="token punctuation">.</span>INNODB_BUFFER_POOL_STATS \G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
POOL_ID<span class="token punctuation">:</span> 0
POOL_SIZE<span class="token punctuation">:</span> 8192
FREE_BUFFERS<span class="token punctuation">:</span> 1
DATABASE_PAGES<span class="token punctuation">:</span> 8173
OLD_DATABASE_PAGES<span class="token punctuation">:</span> 3014
MODIFIED_DATABASE_PAGES<span class="token punctuation">:</span> 0
PENDING_DECOMPRESS<span class="token punctuation">:</span> 0
PENDING_READS<span class="token punctuation">:</span> 0
PENDING_FLUSH_LRU<span class="token punctuation">:</span> 0
PENDING_FLUSH_LIST<span class="token punctuation">:</span> 0
PAGES_MADE_YOUNG<span class="token punctuation">:</span> 15907
PAGES_NOT_MADE_YOUNG<span class="token punctuation">:</span> 3803101
PAGES_MADE_YOUNG_RATE<span class="token punctuation">:</span> 0
PAGES_MADE_NOT_YOUNG_RATE<span class="token punctuation">:</span> 0
NUMBER_PAGES_READ<span class="token punctuation">:</span> 3270
NUMBER_PAGES_CREATED<span class="token punctuation">:</span> 13176
NUMBER_PAGES_WRITTEN<span class="token punctuation">:</span> 15109
PAGES_READ_RATE<span class="token punctuation">:</span> 0
PAGES_CREATE_RATE<span class="token punctuation">:</span> 0
PAGES_WRITTEN_RATE<span class="token punctuation">:</span> 0
NUMBER_PAGES_GET<span class="token punctuation">:</span> 33069332
HIT_RATE<span class="token punctuation">:</span> 0
YOUNG_MAKE_PER_THOUSAND_GETS<span class="token punctuation">:</span> 0
NOT_YOUNG_MAKE_PER_THOUSAND_GETS<span class="token punctuation">:</span> 0
NUMBER_PAGES_READ_AHEAD<span class="token punctuation">:</span> 2713
NUMBER_READ_AHEAD_EVICTED<span class="token punctuation">:</span> 0
READ_AHEAD_RATE<span class="token punctuation">:</span> 0
READ_AHEAD_EVICTED_RATE<span class="token punctuation">:</span> 0
LRU_IO_TOTAL<span class="token punctuation">:</span> 0
LRU_IO_CURRENT<span class="token punctuation">:</span> 0
UNCOMPRESS_TOTAL<span class="token punctuation">:</span> 0
UNCOMPRESS_CURRENT<span class="token punctuation">:</span> 0</span></code></pre>
</div>
<p>
For comparison,
<a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement">
<code class="literal">
SHOW ENGINE INNODB
STATUS
</code>
</a>
output and
<code class="literal">
InnoDB
</code>
buffer
pool status variable output is shown below, based on the same
data set.
</p>
<p>
For more information about
<a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement">
<code class="literal">
SHOW ENGINE INNODB
STATUS
</code>
</a>
output, see
<a class="xref" href="innodb-standard-monitor.html" title="17.17.3 InnoDB Standard Monitor and Lock Monitor Output">
Section 17.17.3, “InnoDB Standard Monitor and Lock Monitor Output”
</a>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa50965093"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">ENGINE</span> INNODB <span class="token keyword">STATUS</span>\G
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token comment" spellcheck="true">----------------------</span>
BUFFER POOL <span class="token operator">AND</span> <span class="token keyword">MEMORY</span>
<span class="token comment" spellcheck="true">----------------------</span>
Total large <span class="token keyword">memory</span> allocated <span class="token number">137428992</span>
Dictionary <span class="token keyword">memory</span> allocated <span class="token number">579084</span>
Buffer pool size <span class="token number">8192</span>
Free buffers <span class="token number">1</span>
<span class="token keyword">Database</span> pages <span class="token number">8173</span>
<span class="token keyword">Old</span> <span class="token keyword">database</span> pages <span class="token number">3014</span>
Modified db pages <span class="token number">0</span>
Pending <span class="token keyword">reads</span> <span class="token number">0</span>
Pending writes: LRU <span class="token number">0</span><span class="token punctuation">,</span> <span class="token keyword">flush</span> <span class="token keyword">list</span> <span class="token number">0</span><span class="token punctuation">,</span> single <span class="token keyword">page</span> <span class="token number">0</span>
Pages made young <span class="token number">15907</span><span class="token punctuation">,</span> <span class="token operator">not</span> young <span class="token number">3803101</span>
<span class="token number">0.00</span> youngs<span class="token operator">/</span>s<span class="token punctuation">,</span> <span class="token number">0.00</span> non<span class="token operator">-</span>youngs<span class="token operator">/</span>s
Pages <span class="token keyword">read</span> <span class="token number">3270</span><span class="token punctuation">,</span> created <span class="token number">13176</span><span class="token punctuation">,</span> written <span class="token number">15109</span>
<span class="token number">0.00</span> <span class="token keyword">reads</span><span class="token operator">/</span>s<span class="token punctuation">,</span> <span class="token number">0.00</span> creates<span class="token operator">/</span>s<span class="token punctuation">,</span> <span class="token number">0.00</span> writes<span class="token operator">/</span>s
<span class="token keyword">No</span> buffer pool <span class="token keyword">page</span> gets since the <span class="token keyword">last</span> printout
Pages <span class="token keyword">read</span> ahead <span class="token number">0.00</span><span class="token operator">/</span>s<span class="token punctuation">,</span> evicted <span class="token keyword">without</span> access <span class="token number">0.00</span><span class="token operator">/</span>s<span class="token punctuation">,</span> <span class="token keyword">Random</span> <span class="token keyword">read</span> ahead <span class="token number">0.00</span><span class="token operator">/</span>s
LRU len: <span class="token number">8173</span><span class="token punctuation">,</span> unzip_LRU len: <span class="token number">0</span>
I<span class="token operator">/</span>O sum<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span>:cur<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">,</span> unzip sum<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span>:cur<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span>
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
For status variable descriptions, see
<a class="xref" href="server-status-variables.html" title="7.1.10 Server Status Variables">
Section 7.1.10, “Server Status Variables”
</a>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa68920426"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">STATUS</span> <span class="token operator">LIKE</span> <span class="token string">'Innodb_buffer%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_dump_status <span class="token punctuation">|</span> not started <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_load_status <span class="token punctuation">|</span> not started <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_resize_status <span class="token punctuation">|</span> not started <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_data <span class="token punctuation">|</span> 8173 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_bytes_data <span class="token punctuation">|</span> 133906432 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_dirty <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_bytes_dirty <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_flushed <span class="token punctuation">|</span> 15109 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_free <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_misc <span class="token punctuation">|</span> 18 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_pages_total <span class="token punctuation">|</span> 8192 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_read_ahead_rnd <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_read_ahead <span class="token punctuation">|</span> 2713 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_read_ahead_evicted <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_read_requests <span class="token punctuation">|</span> 33069332 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_reads <span class="token punctuation">|</span> 558 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_wait_free <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Innodb_buffer_pool_write_requests <span class="token punctuation">|</span> 11985961 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br class="example-break"/>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-log-statistics.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-log-statistics">
</a>
25.6.3.3 Using CLUSTERLOG STATISTICS in the NDB Cluster Management Client
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045092765792">
</a>
<a class="indexterm" name="idm46045092764336">
</a>
<a class="indexterm" name="idm46045092763232">
</a>
<a class="indexterm" name="idm46045092761744">
</a>
<a class="indexterm" name="idm46045092760256">
</a>
<a class="indexterm" name="idm46045092758768">
</a>
<p>
The
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
management client's
<a class="link" href="mysql-cluster-logging-management-commands.html" title="25.6.3.1 NDB Cluster Logging Management Commands">
<code class="literal">
CLUSTERLOG STATISTICS
</code>
</a>
command can provide a number of useful statistics in its output.
Counters providing information about the state of the cluster
are updated at 5-second reporting intervals by the transaction
coordinator (TC) and the local query handler (LQH), and written
to the cluster log.
</p>
<p>
<b>
Transaction coordinator statistics.
</b>
Each transaction has one transaction coordinator, which is
chosen by one of the following methods:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
In a round-robin fashion
</p>
</li>
<li class="listitem">
<p>
By communication proximity
</p>
</li>
<li class="listitem">
<p>
By supplying a data placement hint when the transaction is
started
</p>
</li>
</ul>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
You can determine which TC selection method is used for
transactions started from a given SQL node using the
<a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_optimized_node_selection">
<code class="literal">
ndb_optimized_node_selection
</code>
</a>
system variable.
</p>
</div>
<p>
All operations within the same transaction use the same
transaction coordinator, which reports the following statistics:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Trans count.
</b>
This is the number transactions started in the last
interval using this TC as the transaction coordinator. Any
of these transactions may have committed, have been
aborted, or remain uncommitted at the end of the reporting
interval.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Transactions do not migrate between TCs.
</p>
</div>
</li>
<li class="listitem">
<p>
<b>
Commit count.
</b>
This is the number of transactions using this TC as the
transaction coordinator that were committed in the last
reporting interval. Because some transactions committed in
this reporting interval may have started in a previous
reporting interval, it is possible for
<code class="literal">
Commit
count
</code>
to be greater than
<code class="literal">
Trans
count
</code>
.
</p>
</li>
<li class="listitem">
<p>
<b>
Read count.
</b>
This is the number of primary key read operations using
this TC as the transaction coordinator that were started
in the last reporting interval, including simple reads.
This count also includes reads performed as part of unique
index operations. A unique index read operation generates
2 primary key read operations—1 for the hidden
unique index table, and 1 for the table on which the read
takes place.
</p>
</li>
<li class="listitem">
<p>
<b>
Simple read count.
</b>
This is the number of simple read operations using this TC
as the transaction coordinator that were started in the
last reporting interval.
</p>
</li>
<li class="listitem">
<p>
<b>
Write count.
</b>
This is the number of primary key write operations using
this TC as the transaction coordinator that were started
in the last reporting interval. This includes all inserts,
updates, writes and deletes, as well as writes performed
as part of unique index operations.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
A unique index update operation can generate multiple PK
read and write operations on the index table and on the
base table.
</p>
</div>
</li>
<li class="listitem">
<p>
<b>
AttrInfoCount.
</b>
This is the number of 32-bit data words received in the
last reporting interval for primary key operations using
this TC as the transaction coordinator. For reads, this is
proportional to the number of columns requested. For
inserts and updates, this is proportional to the number of
columns written, and the size of their data. For delete
operations, this is usually zero.
</p>
<p>
Unique index operations generate multiple PK operations and
so increase this count. However, data words sent to describe
the PK operation itself, and the key information sent, are
<span class="emphasis">
<em>
not
</em>
</span>
counted here. Attribute information
sent to describe columns to read for scans, or to describe
ScanFilters, is also not counted in
<code class="literal">
AttrInfoCount
</code>
.
</p>
</li>
<li class="listitem">
<p>
<b>
Concurrent Operations.
</b>
This is the number of primary key or scan operations using
this TC as the transaction coordinator that were started
during the last reporting interval but that were not
completed. Operations increment this counter when they are
started and decrement it when they are completed; this
occurs after the transaction commits. Dirty reads and
writes—as well as failed operations—decrement
this counter.
</p>
<p>
The maximum value that
<code class="literal">
Concurrent
Operations
</code>
can have is the maximum number of
operations that a TC block can support; currently, this is
<code class="literal">
(2 * MaxNoOfConcurrentOperations) + 16 +
MaxNoOfConcurrentTransactions
</code>
. (For more
information about these configuration parameters, see the
<em class="citetitle">
Transaction Parameters
</em>
section of
<a class="xref" href="mysql-cluster-ndbd-definition.html" title="25.4.3.6 Defining NDB Cluster Data Nodes">
Section 25.4.3.6, “Defining NDB Cluster Data Nodes”
</a>
.)
</p>
</li>
<li class="listitem">
<p>
<b>
Abort count.
</b>
This is the number of transactions using this TC as the
transaction coordinator that were aborted during the last
reporting interval. Because some transactions that were
aborted in the last reporting interval may have started in
a previous reporting interval,
<code class="literal">
Abort
count
</code>
can sometimes be greater than
<code class="literal">
Trans count
</code>
.
</p>
</li>
<li class="listitem">
<p>
<b>
Scans.
</b>
This is the number of table scans using this TC as the
transaction coordinator that were started during the last
reporting interval. This does not include range scans
(that is, ordered index scans).
</p>
</li>
<li class="listitem">
<p>
<b>
Range scans.
</b>
This is the number of ordered index scans using this TC as
the transaction coordinator that were started in the last
reporting interval.
</p>
</li>
<li class="listitem">
<p>
<b>
Local reads.
</b>
This is the number of primary-key read operations
performed using a transaction coordinator on a node that
also holds the primary fragment replica of the record.
This count can also be obtained from the
<code class="literal">
LOCAL_READS
</code>
counter in the
<a class="link" href="mysql-cluster-ndbinfo-counters.html" title="25.6.17.13 The ndbinfo counters Table">
<code class="literal">
ndbinfo.counters
</code>
</a>
table.
</p>
</li>
<li class="listitem">
<p>
<b>
Local writes.
</b>
This contains the number of primary-key read operations
that were performed using a transaction coordinator on a
node that also holds the primary fragment replica of the
record. This count can also be obtained from the
<code class="literal">
LOCAL_WRITES
</code>
counter in the
<a class="link" href="mysql-cluster-ndbinfo-counters.html" title="25.6.17.13 The ndbinfo counters Table">
<code class="literal">
ndbinfo.counters
</code>
</a>
table.
</p>
</li>
</ul>
</div>
<p>
<b>
Local query handler statistics (Operations).
</b>
There is 1 cluster event per local query handler block (that
is, 1 per data node process). Operations are recorded in the
LQH where the data they are operating on resides.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
A single transaction may operate on data stored in multiple
LQH blocks.
</p>
</div>
<p>
The
<code class="literal">
Operations
</code>
statistic provides the number
of local operations performed by this LQH block in the last
reporting interval, and includes all types of read and write
operations (insert, update, write, and delete operations). This
also includes operations used to replicate writes. For example,
in a cluster with two fragment replicas, the write to the
primary fragment replica is recorded in the primary LQH, and the
write to the backup is recorded in the backup LQH. Unique key
operations may result in multiple local operations; however,
this does
<span class="emphasis">
<em>
not
</em>
</span>
include local operations
generated as a result of a table scan or ordered index scan,
which are not counted.
</p>
<p>
<b>
Process scheduler statistics.
</b>
<a class="indexterm" name="idm46045092702960">
</a>
In addition to the statistics reported by the transaction
coordinator and local query handler, each
<a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon">
<span class="command">
<strong>
ndbd
</strong>
</span>
</a>
process has a scheduler which also
provides useful metrics relating to the performance of an NDB
Cluster. This scheduler runs in an infinite loop; during each
loop the scheduler performs the following tasks:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
Read any incoming messages from sockets into a job buffer.
</p>
</li>
<li class="listitem">
<p>
Check whether there are any timed messages to be executed;
if so, put these into the job buffer as well.
</p>
</li>
<li class="listitem">
<p>
Execute (in a loop) any messages in the job buffer.
</p>
</li>
<li class="listitem">
<p>
Send any distributed messages that were generated by
executing the messages in the job buffer.
</p>
</li>
<li class="listitem">
<p>
Wait for any new incoming messages.
</p>
</li>
</ol>
</div>
<p>
Process scheduler statistics include the following:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Mean Loop Counter.
</b>
This is the number of loops executed in the third step
from the preceding list. This statistic increases in size
as the utilization of the TCP/IP buffer improves. You can
use this to monitor changes in performance as you add new
data node processes.
</p>
</li>
<li class="listitem">
<p>
<b>
Mean send size and Mean receive size.
</b>
These statistics enable you to gauge the efficiency of,
respectively writes and reads between nodes. The values
are given in bytes. Higher values mean a lower cost per
byte sent or received; the maximum value is 64K.
</p>
</li>
</ul>
</div>
<p>
To cause all cluster log statistics to be logged, you can use
the following command in the
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
management client:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-ndbmgm"><div class="docs-select-all right" id="sa85097823"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ndbmgm"><span class="token prompt">ndb_mgm></span> <span class="token keyword">ALL</span> <span class="token keyword">CLUSTERLOG</span> <span class="token keyword">STATISTICS</span><span class="token operator">=</span>15</code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Setting the threshold for
<code class="literal">
STATISTICS
</code>
to 15
causes the cluster log to become very verbose, and to grow
quite rapidly in size, in direct proportion to the number of
cluster nodes and the amount of activity in the NDB Cluster.
</p>
</div>
<p>
For more information about NDB Cluster management client
commands relating to logging and reporting, see
<a class="xref" href="mysql-cluster-logging-management-commands.html" title="25.6.3.1 NDB Cluster Logging Management Commands">
Section 25.6.3.1, “NDB Cluster Logging Management Commands”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/timezone-problems.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="timezone-problems">
</a>
B.3.3.7 Time Zone Problems
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045053748576">
</a>
<a class="indexterm" name="idm46045053747504">
</a>
<a class="indexterm" name="idm46045053746016">
</a>
<a class="indexterm" name="idm46045053744944">
</a>
<p>
If you have a problem with
<code class="literal">
SELECT NOW()
</code>
returning values in UTC and not your local time, you have to
tell the server your current time zone. The same applies if
<a class="link" href="date-and-time-functions.html#function_unix-timestamp">
<code class="literal">
UNIX_TIMESTAMP()
</code>
</a>
returns the
wrong value. This should be done for the environment in which
the server runs (for example, in
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
or
<a class="link" href="mysql-server.html" title="6.3.3 mysql.server — MySQL Server Startup Script">
<span class="command">
<strong>
mysql.server
</strong>
</span>
</a>
). See
<a class="xref" href="environment-variables.html" title="6.9 Environment Variables">
Section 6.9, “Environment Variables”
</a>
.
</p>
<p>
You can set the time zone for the server with the
<a class="link" href="mysqld-safe.html#option_mysqld_safe_timezone">
<code class="option">
--timezone=
<em class="replaceable">
<code>
timezone_name
</code>
</em>
</code>
</a>
option to
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
. You can also set it
by setting the
<code class="literal">
TZ
</code>
environment variable
before you start
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
.
</p>
<p>
The permissible values for
<a class="link" href="mysqld-safe.html#option_mysqld_safe_timezone">
<code class="option">
--timezone
</code>
</a>
or
<code class="literal">
TZ
</code>
are system dependent. Consult your
operating system documentation to see what values are
acceptable.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/custom-benchmarks.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="custom-benchmarks">
</a>
10.13.2 Using Your Own Benchmarks
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045222073792">
</a>
<a class="indexterm" name="idm46045222072752">
</a>
<p>
Benchmark your application and database to find out where the
bottlenecks are. After fixing one bottleneck (or by replacing it
with a
<span class="quote">
“
<span class="quote">
dummy
</span>
”
</span>
module), you can proceed to identify
the next bottleneck. Even if the overall performance for your
application currently is acceptable, you should at least make a
plan for each bottleneck and decide how to solve it if someday
you really need the extra performance.
</p>
<p>
A free benchmark suite is the Open Source Database Benchmark,
available at
<a class="ulink" href="http://osdb.sourceforge.net/" target="_blank">
http://osdb.sourceforge.net/
</a>
.
</p>
<p>
It is very common for a problem to occur only when the system is
very heavily loaded. We have had many customers who contact us
when they have a (tested) system in production and have
encountered load problems. In most cases, performance problems
turn out to be due to issues of basic database design (for
example, table scans are not good under high load) or problems
with the operating system or libraries. Most of the time, these
problems would be much easier to fix if the systems were not
already in production.
</p>
<p>
To avoid problems like this, benchmark your whole application
under the worst possible load:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="mysqlslap.html" title="6.5.7 mysqlslap — A Load Emulation Client">
<span class="command">
<strong>
mysqlslap
</strong>
</span>
</a>
program can be helpful for
simulating a high load produced by multiple clients issuing
queries simultaneously. See
<a class="xref" href="mysqlslap.html" title="6.5.7 mysqlslap — A Load Emulation Client">
Section 6.5.7, “mysqlslap — A Load Emulation Client”
</a>
.
</p>
</li>
<li class="listitem">
<p>
You can also try benchmarking packages such as SysBench and
DBT2, available at
<a class="ulink" href="https://launchpad.net/sysbench" target="_blank">
https://launchpad.net/sysbench
</a>
, and
<a class="ulink" href="http://osdldbt.sourceforge.net/#dbt2" target="_blank">
http://osdldbt.sourceforge.net/#dbt2
</a>
.
</p>
</li>
</ul>
</div>
<p>
These programs or packages can bring a system to its knees, so
be sure to use them only on your development systems.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/point-in-time-recovery.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="point-in-time-recovery">
</a>
9.5 Point-in-Time (Incremental) Recovery
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="point-in-time-recovery-binlog.html">
9.5.1 Point-in-Time Recovery Using Binary Log
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="point-in-time-recovery-positions.html">
9.5.2 Point-in-Time Recovery Using Event Positions
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045230822784">
</a>
<a class="indexterm" name="idm46045230821744">
</a>
<a class="indexterm" name="idm46045230820256">
</a>
<a class="indexterm" name="idm46045230819184">
</a>
<p>
Point-in-time recovery refers to recovery of data changes up to a
given point in time. Typically, this type of recovery is performed
after restoring a full backup that brings the server to its state
as of the time the backup was made. (The full backup can be made
in several ways, such as those listed in
<a class="xref" href="backup-methods.html" title="9.2 Database Backup Methods">
Section 9.2, “Database Backup Methods”
</a>
.) Point-in-time recovery then
brings the server up to date incrementally from the time of the
full backup to a more recent time.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/connection-control-installation.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="connection-control-installation">
</a>
8.4.2.1 Connection-Control Plugin Installation
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045242132656">
</a>
<a class="indexterm" name="idm46045242131152">
</a>
<a class="indexterm" name="idm46045242129664">
</a>
<a class="indexterm" name="idm46045242128144">
</a>
<p>
This section describes how to install the connection-control
plugins,
<code class="literal">
CONNECTION_CONTROL
</code>
and
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
. For
general information about installing plugins, see
<a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins">
Section 7.6.1, “Installing and Uninstalling Plugins”
</a>
.
</p>
<p>
To be usable by the server, the plugin library file must be
located in the MySQL plugin directory (the directory named by
the
<a class="link" href="server-system-variables.html#sysvar_plugin_dir">
<code class="literal">
plugin_dir
</code>
</a>
system
variable). If necessary, configure the plugin directory location
by setting the value of
<a class="link" href="server-system-variables.html#sysvar_plugin_dir">
<code class="literal">
plugin_dir
</code>
</a>
at server startup.
</p>
<p>
The plugin library file base name is
<code class="literal">
connection_control
</code>
. The file name suffix
differs per platform (for example,
<code class="filename">
.so
</code>
for
Unix and Unix-like systems,
<code class="filename">
.dll
</code>
for
Windows).
</p>
<p>
To load the plugins at server startup, use the
<a class="link" href="server-options.html#option_mysqld_plugin-load-add">
<code class="option">
--plugin-load-add
</code>
</a>
option to name
the library file that contains them. With this plugin-loading
method, the option must be given each time the server starts.
For example, put these lines in the server
<code class="filename">
my.cnf
</code>
file, adjusting the
<code class="filename">
.so
</code>
suffix for your platform as necessary:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa35213923"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span>
<span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>connection_control.so</span></code></pre>
</div>
<p>
After modifying
<code class="filename">
my.cnf
</code>
, restart the server
to cause the new settings to take effect.
</p>
<p>
Alternatively, to load the plugins at runtime, use these
statements, adjusting the
<code class="filename">
.so
</code>
suffix for
your platform as necessary:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24626543"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSTALL</span> <span class="token keyword">PLUGIN</span> CONNECTION_CONTROL
<span class="token keyword">SONAME</span> <span class="token string">'connection_control.so'</span><span class="token punctuation">;</span>
<span class="token keyword">INSTALL</span> <span class="token keyword">PLUGIN</span> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
<span class="token keyword">SONAME</span> <span class="token string">'connection_control.so'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
<a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement">
<code class="literal">
INSTALL PLUGIN
</code>
</a>
loads the plugin
immediately, and also registers it in the
<code class="literal">
mysql.plugins
</code>
system table to cause the
server to load it for each subsequent normal startup without the
need for
<a class="link" href="server-options.html#option_mysqld_plugin-load-add">
<code class="option">
--plugin-load-add
</code>
</a>
.
</p>
<p>
To verify plugin installation, examine the Information Schema
<a class="link" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table">
<code class="literal">
PLUGINS
</code>
</a>
table or use the
<a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement">
<code class="literal">
SHOW PLUGINS
</code>
</a>
statement (see
<a class="xref" href="obtaining-plugin-information.html" title="7.6.2 Obtaining Server Plugin Information">
Section 7.6.2, “Obtaining Server Plugin Information”
</a>
). For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35867110"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> PLUGIN_NAME<span class="token punctuation">,</span> PLUGIN_STATUS
<span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span><span class="token keyword">PLUGINS</span>
<span class="token keyword">WHERE</span> PLUGIN_NAME <span class="token operator">LIKE</span> <span class="token string">'connection%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> PLUGIN_NAME <span class="token punctuation">|</span> PLUGIN_STATUS <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CONNECTION_CONTROL <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
If a plugin fails to initialize, check the server error log for
diagnostic messages.
</p>
<p>
If the plugins have been previously registered with
<a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement">
<code class="literal">
INSTALL PLUGIN
</code>
</a>
or are loaded with
<a class="link" href="server-options.html#option_mysqld_plugin-load-add">
<code class="option">
--plugin-load-add
</code>
</a>
, you can use
the
<code class="option">
--connection-control
</code>
and
<code class="option">
--connection-control-failed-login-attempts
</code>
options at server startup to control plugin activation. For
example, to load the plugins at startup and prevent them from
being removed at runtime, use these options:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa13300292"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span>
<span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>connection_control.so</span>
<span class="token constant">connection-control</span><span class="token attr-value"><span class="token punctuation">=</span>FORCE_PLUS_PERMANENT</span>
<span class="token constant">connection-control-failed-login-attempts</span><span class="token attr-value"><span class="token punctuation">=</span>FORCE_PLUS_PERMANENT</span></code></pre>
</div>
<p>
If it is desired to prevent the server from running without a
given connection-control plugin, use an option value of
<code class="literal">
FORCE
</code>
or
<code class="literal">
FORCE_PLUS_PERMANENT
</code>
to force server startup
to fail if the plugin does not initialize successfully.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
It is possible to install one plugin without the other, but
both must be installed for full connection-control capability.
In particular, installing only the
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
plugin is of little use because, without the
<code class="literal">
CONNECTION_CONTROL
</code>
plugin to provide the
data that populates the
<a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table">
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
</a>
table, the table is always empty.
</p>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="connection-control-installation.html#connection-control-plugin-delay-configuration" title="Connection Delay Configuration">
Connection Delay Configuration
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="connection-control-installation.html#connection-control-plugin-failure-assessment" title="Connection Failure Assessment">
Connection Failure Assessment
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="connection-control-installation.html#connection-control-plugin-failure-monitoring" title="Connection Failure Monitoring">
Connection Failure Monitoring
</a>
</p>
</li>
</ul>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="connection-control-plugin-delay-configuration">
</a>
Connection Delay Configuration
</h5>
</div>
</div>
</div>
<p>
To enable configuring its operation, the
<code class="literal">
CONNECTION_CONTROL
</code>
plugin exposes these
system variables:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
:
The number of consecutive failed connection attempts
permitted to accounts before the server adds a delay for
subsequent connection attempts. To disable
failed-connection counting, set
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
to zero.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
:
The minimum delay in milliseconds for connection failures
above the threshold.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
:
The maximum delay in milliseconds for connection failures
above the threshold.
</p>
</li>
</ul>
</div>
<p>
If
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
is nonzero, failed-connection counting is enabled and has
these properties:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The delay is zero up through
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
consecutive failed connection attempts.
</p>
</li>
<li class="listitem">
<p>
Thereafter, the server adds an increasing delay for
subsequent consecutive attempts, until a successful
connection occurs. The initial unadjusted delays begin at
1000 milliseconds (1 second) and increase by 1000
milliseconds per attempt. That is, once delay has been
activated for an account, the unadjusted delays for
subsequent failed attempts are 1000 milliseconds, 2000
milliseconds, 3000 milliseconds, and so forth.
</p>
</li>
<li class="listitem">
<p>
The actual delay experienced by a client is the unadjusted
delay, adjusted to lie within the values of the
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
system variables, inclusive.
</p>
</li>
<li class="listitem">
<p>
Once delay has been activated for an account, the first
successful connection thereafter by the account also
experiences a delay, but failure counting is reset for
subsequent connections.
</p>
</li>
</ul>
</div>
<p>
For example, with the default
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
value of 3, there is no delay for the first three consecutive
failed connection attempts by an account. The actual adjusted
delays experienced by the account for the fourth and
subsequent failed connections depend on the
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
are 1000 and 20000, the adjusted delays are the same as
the unadjusted delays, up to a maximum of 20000
milliseconds. The fourth and subsequent failed connections
are delayed by 1000 milliseconds, 2000 milliseconds, 3000
milliseconds, and so forth.
</p>
</li>
<li class="listitem">
<p>
If
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
are 1500 and 20000, the adjusted delays for the fourth and
subsequent failed connections are 1500 milliseconds, 2000
milliseconds, 3000 milliseconds, and so forth, up to a
maximum of 20000 milliseconds.
</p>
</li>
<li class="listitem">
<p>
If
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
are 2000 and 3000, the adjusted delays for the fourth and
subsequent failed connections are 2000 milliseconds, 2000
milliseconds, and 3000 milliseconds, with all subsequent
failed connections also delayed by 3000 milliseconds.
</p>
</li>
</ul>
</div>
<p>
You can set the
<code class="literal">
CONNECTION_CONTROL
</code>
system
variables at server startup or runtime. Suppose that you want
to permit four consecutive failed connection attempts before
the server starts delaying its responses, with a minimum delay
of 2000 milliseconds. To set the relevant variables at server
startup, put these lines in the server
<code class="filename">
my.cnf
</code>
file:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa77131483"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span>
<span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>connection_control.so</span>
<span class="token constant">connection_control_failed_connections_threshold</span><span class="token attr-value"><span class="token punctuation">=</span>4</span>
<span class="token constant">connection_control_min_connection_delay</span><span class="token attr-value"><span class="token punctuation">=</span>2000</span></code></pre>
</div>
<p>
To set and persist the variables at runtime, use these
statements:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa19331394"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">PERSIST</span> connection_control_failed_connections_threshold <span class="token operator">=</span> <span class="token number">4</span><span class="token punctuation">;</span>
<span class="token keyword">SET</span> <span class="token keyword">PERSIST</span> connection_control_min_connection_delay <span class="token operator">=</span> <span class="token number">2000</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
<a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment">
<code class="literal">
SET
PERSIST
</code>
</a>
sets a value for the running MySQL instance.
It also saves the value, causing it to carry over to
subsequent server restarts. To change a value for the running
MySQL instance without having it carry over to subsequent
restarts, use the
<code class="literal">
GLOBAL
</code>
keyword rather
than
<code class="literal">
PERSIST
</code>
. See
<a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment">
Section 15.7.6.1, “SET Syntax for Variable Assignment”
</a>
.
</p>
<p>
The
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
and
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
system variables both have minimum and maximum values of 1000
and 2147483647. In addition, the permitted range of values of
each variable also depends on the current value of the other:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
cannot be set greater than the current value of
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
cannot be set less than the current value of
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
.
</p>
</li>
</ul>
</div>
<p>
Thus, to make the changes required for some configurations,
you might need to set the variables in a specific order.
Suppose that the current minimum and maximum delays are 1000
and 2000, and that you want to set them to 3000 and 5000. You
cannot first set
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
to 3000 because that is greater than the current
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
value of 2000. Instead, set
<a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay">
<code class="literal">
connection_control_max_connection_delay
</code>
</a>
to 5000, then set
<a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay">
<code class="literal">
connection_control_min_connection_delay
</code>
</a>
to 3000.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="connection-control-plugin-failure-assessment">
</a>
Connection Failure Assessment
</h5>
</div>
</div>
</div>
<p>
When the
<code class="literal">
CONNECTION_CONTROL
</code>
plugin is
installed, it checks connection attempts and tracks whether
they fail or succeed. For this purpose, a failed connection
attempt is one for which the client user and host match a
known MySQL account but the provided credentials are
incorrect, or do not match any known account.
</p>
<p>
Failed-connection counting is based on the user/host
combination for each connection attempt. Determination of the
applicable user name and host name takes proxying into account
and occurs as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If the client user proxies another user, the account for
failed-connection counting is the proxying user, not the
proxied user. For example, if
<code class="literal">
[email protected]
</code>
proxies
<code class="literal">
[email protected]
</code>
, connection
counting uses the proxying user,
<code class="literal">
[email protected]
</code>
, rather than
the proxied user,
<code class="literal">
[email protected]
</code>
. Both
<code class="literal">
[email protected]
</code>
and
<code class="literal">
[email protected]
</code>
must have valid
entries in the
<code class="literal">
mysql.user
</code>
system table
and a proxy relationship between them must be defined in
the
<code class="literal">
mysql.proxies_priv
</code>
system table
(see
<a class="xref" href="proxy-users.html" title="8.2.19 Proxy Users">
Section 8.2.19, “Proxy Users”
</a>
).
</p>
</li>
<li class="listitem">
<p>
If the client user does not proxy another user, but does
match a
<code class="literal">
mysql.user
</code>
entry, counting uses
the
<a class="link" href="information-functions.html#function_current-user">
<code class="literal">
CURRENT_USER()
</code>
</a>
value
corresponding to that entry. For example, if a user
<code class="literal">
user1
</code>
connecting from a host
<code class="literal">
host1.example.com
</code>
matches a
<code class="literal">
[email protected]
</code>
entry, counting
uses
<code class="literal">
[email protected]
</code>
. If the
user matches a
<code class="literal">
user1@%.example.com
</code>
,
<code class="literal">
user1@%.com
</code>
, or
<code class="literal">
user1@%
</code>
entry instead, counting uses
<code class="literal">
user1@%.example.com
</code>
,
<code class="literal">
user1@%.com
</code>
, or
<code class="literal">
user1@%
</code>
, respectively.
</p>
</li>
</ul>
</div>
<p>
For the cases just described, the connection attempt matches
some
<code class="literal">
mysql.user
</code>
entry, and whether the
request succeeds or fails depends on whether the client
provides the correct authentication credentials. For example,
if the client presents an incorrect password, the connection
attempt fails.
</p>
<p>
If the connection attempt matches no
<code class="literal">
mysql.user
</code>
entry, the attempt fails. In
this case, no
<a class="link" href="information-functions.html#function_current-user">
<code class="literal">
CURRENT_USER()
</code>
</a>
value is available and connection-failure counting uses the
user name provided by the client and the client host as
determined by the server. For example, if a client attempts to
connect as user
<code class="literal">
user2
</code>
from host
<code class="literal">
host2.example.com
</code>
, the user name part is
available in the client request and the server determines the
host information. The user/host combination used for counting
is
<code class="literal">
[email protected]
</code>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The server maintains information about which client hosts
can possibly connect to the server (essentially the union of
host values for
<code class="literal">
mysql.user
</code>
entries). If a
client attempts to connect from any other host, the server
rejects the attempt at an early stage of connection setup:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa14216421"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR 1130 (HY000): Host '<em class="replaceable">host_name</em>' is not
allowed to connect to this MySQL server</code></pre>
</div>
<p>
Because this type of rejection occurs so early,
<code class="literal">
CONNECTION_CONTROL
</code>
does not see it, and
does not count it.
</p>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="connection-control-plugin-failure-monitoring">
</a>
Connection Failure Monitoring
</h5>
</div>
</div>
</div>
<p>
To monitor failed connections, use these information sources:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="connection-control-variables.html#statvar_Connection_control_delay_generated">
<code class="literal">
Connection_control_delay_generated
</code>
</a>
status variable indicates the number of times the server
added a delay to its response to a failed connection
attempt. This does not count attempts that occur before
reaching the threshold defined by the
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
system variable.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
INFORMATION_SCHEMA
</code>
<a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table">
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
</a>
table provides information about the current number of
consecutive failed connection attempts per account
(user/host combination). This counts all failed attempts,
regardless of whether they were delayed.
</p>
</li>
</ul>
</div>
<p>
Assigning a value to
<a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold">
<code class="literal">
connection_control_failed_connections_threshold
</code>
</a>
at runtime has these effects:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
All accumulated failed-connection counters are reset to
zero.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="connection-control-variables.html#statvar_Connection_control_delay_generated">
<code class="literal">
Connection_control_delay_generated
</code>
</a>
status variable is reset to zero.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table">
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
</a>
table becomes empty.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/view-updatability.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="view-updatability">
</a>
27.5.3 Updatable and Insertable Views
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045081825936">
</a>
<a class="indexterm" name="idm46045081824896">
</a>
<a class="indexterm" name="idm46045081823408">
</a>
<a class="indexterm" name="idm46045081821920">
</a>
<p>
Some views are updatable and references to them can be used to
specify tables to be updated in data change statements. That is,
you can use them in statements such as
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
, or
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
to update the contents of
the underlying table. Derived tables and common table expressions
can also be specified in multiple-table
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
and
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statements, but can only be
used for reading data to specify rows to be updated or deleted.
Generally, the view references must be updatable, meaning that
they may be merged and not materialized. Composite views have more
complex rules.
</p>
<p>
For a view to be updatable, there must be a one-to-one
relationship between the rows in the view and the rows in the
underlying table. There are also certain other constructs that
make a view nonupdatable. To be more specific, a view is not
updatable if it contains any of the following:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Aggregate functions or window functions
(
<a class="link" href="aggregate-functions.html#function_sum">
<code class="literal">
SUM()
</code>
</a>
,
<a class="link" href="aggregate-functions.html#function_min">
<code class="literal">
MIN()
</code>
</a>
,
<a class="link" href="aggregate-functions.html#function_max">
<code class="literal">
MAX()
</code>
</a>
,
<a class="link" href="aggregate-functions.html#function_count">
<code class="literal">
COUNT()
</code>
</a>
, and so forth)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
DISTINCT
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
GROUP BY
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
HAVING
</code>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION
</code>
</a>
or
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION ALL
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
Subquery in the select list
</p>
<p>
Nondependent subqueries in the select list fail for
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
, but are okay for
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
. For dependent
subqueries in the select list, no data change statements are
permitted.
</p>
</li>
<li class="listitem">
<p>
Certain joins (see additional join discussion later in this
section)
</p>
</li>
<li class="listitem">
<p>
Reference to nonupdatable view in the
<code class="literal">
FROM
</code>
clause
</p>
</li>
<li class="listitem">
<p>
Subquery in the
<code class="literal">
WHERE
</code>
clause that refers to
a table in the
<code class="literal">
FROM
</code>
clause
</p>
</li>
<li class="listitem">
<p>
Refers only to literal values (in this case, there is no
underlying table to update)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ALGORITHM = TEMPTABLE
</code>
(use of a temporary
table always makes a view nonupdatable)
</p>
</li>
<li class="listitem">
<p>
Multiple references to any column of a base table (fails for
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
, okay for
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
)
</p>
</li>
</ul>
</div>
<a class="indexterm" name="idm46045081781968">
</a>
<p>
A generated column in a view is considered updatable because it is
possible to assign to it. However, if such a column is updated
explicitly, the only permitted value is
<code class="literal">
DEFAULT
</code>
. For information about generated
columns, see
<a class="xref" href="create-table-generated-columns.html" title="15.1.20.8 CREATE TABLE and Generated Columns">
Section 15.1.20.8, “CREATE TABLE and Generated Columns”
</a>
.
</p>
<p>
It is sometimes possible for a multiple-table view to be
updatable, assuming that it can be processed with the
<code class="literal">
MERGE
</code>
algorithm. For this to work, the view
must use an inner join (not an outer join or a
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION
</code>
</a>
). Also, only a single table
in the view definition can be updated, so the
<code class="literal">
SET
</code>
clause must name only columns from one of
the tables in the view. Views that use
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION ALL
</code>
</a>
are not
permitted even though they might be theoretically updatable.
</p>
<p>
With respect to insertability (being updatable with
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements), an updatable
view is insertable if it also satisfies these additional
requirements for the view columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
There must be no duplicate view column names.
</p>
</li>
<li class="listitem">
<p>
The view must contain all columns in the base table that do
not have a default value.
</p>
</li>
<li class="listitem">
<p>
The view columns must be simple column references. They must
not be expressions, such as these:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72536273"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token number">3.14159</span>
col1 <span class="token operator">+</span> <span class="token number">3</span>
<span class="token function">UPPER</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span>
col3 <span class="token operator">/</span> col4
<span class="token punctuation">(</span><em class="replaceable">subquery</em><span class="token punctuation">)</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
MySQL sets a flag, called the view updatability flag, at
<a class="link" href="create-view.html" title="15.1.23 CREATE VIEW Statement">
<code class="literal">
CREATE VIEW
</code>
</a>
time. The flag is set
to
<code class="literal">
YES
</code>
(true) if
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
and
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
(and similar operations) are
legal for the view. Otherwise, the flag is set to
<code class="literal">
NO
</code>
(false). The
<code class="literal">
IS_UPDATABLE
</code>
column in the Information Schema
<a class="link" href="information-schema-views-table.html" title="28.3.47 The INFORMATION_SCHEMA VIEWS Table">
<code class="literal">
VIEWS
</code>
</a>
table displays the status of
this flag. It means that the server always knows whether a view is
updatable.
</p>
<p>
If a view is not updatable, statements such
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
, and
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
are illegal and are
rejected. (Even if a view is updatable, it might not be possible
to insert into it, as described elsewhere in this section.)
</p>
<p>
The updatability of views may be affected by the value of the
<a class="link" href="server-system-variables.html#sysvar_updatable_views_with_limit">
<code class="literal">
updatable_views_with_limit
</code>
</a>
system
variable. See
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
.
</p>
<p>
For the following discussion, suppose that these tables and views
exist:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40240634"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>x <span class="token datatype">INTEGER</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span>c <span class="token datatype">INTEGER</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">VIEW</span> vmat <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> <span class="token function">SUM</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token keyword">AS</span> s <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">VIEW</span> vup <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t2<span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">VIEW</span> vjoin <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> vmat <span class="token keyword">JOIN</span> vup <span class="token keyword">ON</span> vmat<span class="token punctuation">.</span>s<span class="token operator">=</span>vup<span class="token punctuation">.</span>c<span class="token punctuation">;</span></code></pre>
</div>
<p>
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
, and
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statements are permitted as
follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
: The insert table of an
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement may be a view
reference that is merged. If the view is a join view, all
components of the view must be updatable (not materialized).
For a multiple-table updatable view,
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
can work if it inserts
into a single table.
</p>
<p>
This statement is invalid because one component of the join
view is nonupdatable:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa1114332"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> vjoin <span class="token punctuation">(</span>c<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is valid; the view contains no materialized
components:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa93305356"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> vup <span class="token punctuation">(</span>c<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
: The table or tables to
be updated in an
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statement may be view references that are merged. If a view is
a join view, at least one component of the view must be
updatable (this differs from
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
).
</p>
<p>
In a multiple-table
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statement, the updated table references of the statement must
be base tables or updatable view references. Nonupdated table
references may be materialized views or derived tables.
</p>
<p>
This statement is valid; column
<code class="literal">
c
</code>
is from
the updatable part of the join view:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa23965905"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> vjoin <span class="token keyword">SET</span> c<span class="token operator">=</span>c<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is invalid; column
<code class="literal">
x
</code>
is from
the nonupdatable part:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa51658981"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> vjoin <span class="token keyword">SET</span> x<span class="token operator">=</span>x<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is valid; the updated table reference of the
multiple-table
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
is an
updatable view (
<code class="literal">
vup
</code>
):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40383159"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> vup <span class="token keyword">JOIN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">SUM</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token keyword">AS</span> s <span class="token keyword">FROM</span> t1<span class="token punctuation">)</span> <span class="token keyword">AS</span> dt <span class="token keyword">ON</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">SET</span> c<span class="token operator">=</span>c<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is invalid; it tries to update a materialized
derived table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa90771092"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> vup <span class="token keyword">JOIN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">SUM</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token keyword">AS</span> s <span class="token keyword">FROM</span> t1<span class="token punctuation">)</span> <span class="token keyword">AS</span> dt <span class="token keyword">ON</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">SET</span> s<span class="token operator">=</span>s<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
: The table or tables to
be deleted from in a
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statement must be merged views. Join views are not allowed
(this differs from
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
and
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
).
</p>
<p>
This statement is invalid because the view is a join view:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa76969651"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">DELETE</span> vjoin <span class="token keyword">WHERE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is valid because the view is a merged
(updatable) view:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa30662876"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">DELETE</span> vup <span class="token keyword">WHERE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This statement is valid because it deletes from a merged
(updatable) view:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa71170953"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">DELETE</span> vup <span class="token keyword">FROM</span> vup <span class="token keyword">JOIN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">SUM</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token keyword">AS</span> s <span class="token keyword">FROM</span> t1<span class="token punctuation">)</span> <span class="token keyword">AS</span> dt <span class="token keyword">ON</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
Additional discussion and examples follow.
</p>
<p>
Earlier discussion in this section pointed out that a view is not
insertable if not all columns are simple column references (for
example, if it contains columns that are expressions or composite
expressions). Although such a view is not insertable, it can be
updatable if you update only columns that are not expressions.
Consider this view:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa48496003"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">VIEW</span> v <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> <span class="token number">1</span> <span class="token keyword">AS</span> col2 <span class="token keyword">FROM</span> t<span class="token punctuation">;</span></code></pre>
</div>
<p>
This view is not insertable because
<code class="literal">
col2
</code>
is an
expression. But it is updatable if the update does not try to
update
<code class="literal">
col2
</code>
. This update is permissible:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa46451590"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> v <span class="token keyword">SET</span> col1 <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This update is not permissible because it attempts to update an
expression column:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa71790895"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> v <span class="token keyword">SET</span> col2 <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
If a table contains an
<code class="literal">
AUTO_INCREMENT
</code>
column,
inserting into an insertable view on the table that does not
include the
<code class="literal">
AUTO_INCREMENT
</code>
column does not
change the value of
<a class="link" href="information-functions.html#function_last-insert-id">
<code class="literal">
LAST_INSERT_ID()
</code>
</a>
, because the side
effects of inserting default values into columns not part of the
view should not be visible.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/gis-mysql-specific-functions.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="gis-mysql-specific-functions">
</a>
14.16.5 MySQL-Specific Functions That Create Geometry Values
</h3>
</div>
</div>
</div>
<p>
MySQL provides a set of useful nonstandard functions for creating
geometry values. The functions described in this section are MySQL
extensions to the OpenGIS specification.
</p>
<p>
These functions produce geometry objects from either WKB values or
geometry objects as arguments. If any argument is not a proper WKB
or geometry representation of the proper object type, the return
value is
<code class="literal">
NULL
</code>
.
</p>
<p>
For example, you can insert the geometry return value from
<a class="link" href="gis-mysql-specific-functions.html#function_point">
<code class="literal">
Point()
</code>
</a>
directly into a
<code class="literal">
POINT
</code>
column:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa47660594"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>pt_col<span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token function">Point</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a name="function_geomcollection">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection(
<em class="replaceable">
<code>
g
</code>
</em>
[,
<em class="replaceable">
<code>
g
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197753232">
</a>
<p>
Constructs a
<code class="literal">
GeomCollection
</code>
value from the
geometry arguments.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
returns all
the proper geometries contained in the arguments even if a
nonsupported geometry is present.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
with no
arguments is permitted as a way to create an empty geometry.
Also, functions such as
<a class="link" href="gis-wkt-functions.html#function_st-geomfromtext">
<code class="literal">
ST_GeomFromText()
</code>
</a>
that accept
WKT geometry collection arguments understand both OpenGIS
<code class="literal">
'GEOMETRYCOLLECTION EMPTY'
</code>
standard syntax
and MySQL
<code class="literal">
'GEOMETRYCOLLECTION()'
</code>
nonstandard syntax.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
and
<a class="link" href="gis-mysql-specific-functions.html#function_geometrycollection">
<code class="literal">
GeometryCollection()
</code>
</a>
are
synonymous, with
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
the preferred
function.
</p>
</li>
<li class="listitem">
<a name="function_geometrycollection">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geometrycollection">
<code class="literal">
GeometryCollection(
<em class="replaceable">
<code>
g
</code>
</em>
[,
<em class="replaceable">
<code>
g
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197734608">
</a>
<p>
Constructs a
<code class="literal">
GeomCollection
</code>
value from the
geometry arguments.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geometrycollection">
<code class="literal">
GeometryCollection()
</code>
</a>
returns
all the proper geometries contained in the arguments even if a
nonsupported geometry is present.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geometrycollection">
<code class="literal">
GeometryCollection()
</code>
</a>
with no
arguments is permitted as a way to create an empty geometry.
Also, functions such as
<a class="link" href="gis-wkt-functions.html#function_st-geomfromtext">
<code class="literal">
ST_GeomFromText()
</code>
</a>
that accept
WKT geometry collection arguments understand both OpenGIS
<code class="literal">
'GEOMETRYCOLLECTION EMPTY'
</code>
standard syntax
and MySQL
<code class="literal">
'GEOMETRYCOLLECTION()'
</code>
nonstandard syntax.
</p>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
and
<a class="link" href="gis-mysql-specific-functions.html#function_geometrycollection">
<code class="literal">
GeometryCollection()
</code>
</a>
are
synonymous, with
<a class="link" href="gis-mysql-specific-functions.html#function_geomcollection">
<code class="literal">
GeomCollection()
</code>
</a>
the preferred
function.
</p>
</li>
<li class="listitem">
<a name="function_linestring">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_linestring">
<code class="literal">
LineString(
<em class="replaceable">
<code>
pt
</code>
</em>
[,
<em class="replaceable">
<code>
pt
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197716032">
</a>
<p>
Constructs a
<code class="literal">
LineString
</code>
value from a number
of
<code class="literal">
Point
</code>
or WKB
<code class="literal">
Point
</code>
arguments. If the number of arguments is less than two, the
return value is
<code class="literal">
NULL
</code>
.
</p>
</li>
<li class="listitem">
<a name="function_multilinestring">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_multilinestring">
<code class="literal">
MultiLineString(
<em class="replaceable">
<code>
ls
</code>
</em>
[,
<em class="replaceable">
<code>
ls
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197705712">
</a>
<p>
Constructs a
<code class="literal">
MultiLineString
</code>
value using
<code class="literal">
LineString
</code>
or WKB
<code class="literal">
LineString
</code>
arguments.
</p>
</li>
<li class="listitem">
<a name="function_multipoint">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_multipoint">
<code class="literal">
MultiPoint(
<em class="replaceable">
<code>
pt
</code>
</em>
[,
<em class="replaceable">
<code>
pt2
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197696256">
</a>
<p>
Constructs a
<code class="literal">
MultiPoint
</code>
value using
<code class="literal">
Point
</code>
or WKB
<code class="literal">
Point
</code>
arguments.
</p>
</li>
<li class="listitem">
<a name="function_multipolygon">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_multipolygon">
<code class="literal">
MultiPolygon(
<em class="replaceable">
<code>
poly
</code>
</em>
[,
<em class="replaceable">
<code>
poly
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197686720">
</a>
<p>
Constructs a
<code class="literal">
MultiPolygon
</code>
value from a set
of
<code class="literal">
Polygon
</code>
or WKB
<code class="literal">
Polygon
</code>
arguments.
</p>
</li>
<li class="listitem">
<a name="function_point">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_point">
<code class="literal">
Point(
<em class="replaceable">
<code>
x
</code>
</em>
,
<em class="replaceable">
<code>
y
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197677280">
</a>
<p>
Constructs a
<code class="literal">
Point
</code>
using its coordinates.
</p>
</li>
<li class="listitem">
<a name="function_polygon">
</a>
<p>
<a class="link" href="gis-mysql-specific-functions.html#function_polygon">
<code class="literal">
Polygon(
<em class="replaceable">
<code>
ls
</code>
</em>
[,
<em class="replaceable">
<code>
ls
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045197669312">
</a>
<p>
Constructs a
<code class="literal">
Polygon
</code>
value from a number of
<code class="literal">
LineString
</code>
or WKB
<code class="literal">
LineString
</code>
arguments. If any argument does
not represent a
<code class="literal">
LinearRing
</code>
(that is, not a
closed and simple
<code class="literal">
LineString
</code>
), the return
value is
<code class="literal">
NULL
</code>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/group-replication-deploying-locally.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="group-replication-deploying-locally">
</a>
20.2.2 Deploying Group Replication Locally
</h3>
</div>
</div>
</div>
<p>
The most common way to deploy Group Replication is using multiple
server instances, to provide high availability. It is also
possible to deploy Group Replication locally, for example for
testing purposes. This section explains how you can deploy Group
Replication locally.
</p>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
Group Replication is usually deployed on multiple hosts because
this ensures that high-availability is provided. The
instructions in this section are not suitable for production
deployments because all MySQL server instances are running on
the same single host. In the event of failure of this host, the
whole group fails. Therefore this information should be used for
testing purposes and it should not be used in a production
environments.
</p>
</div>
<p>
This section explains how to create a replication group with three
MySQL Server instances on one physical machine. This means that
three data directories are needed, one per server instance, and
that you need to configure each instance independently. This -
procedure assumes that MySQL Server was downloaded and unpacked -
into the directory named
<code class="literal">
mysql-8.4
</code>
. Each MySQL server
instance requires a specific data directory. Create a directory
named
<code class="literal">
data
</code>
, then in that directory create a
subdirectory for each server instance, for example s1, s2 and s3,
and initialize each one.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa78159816"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql-8<span class="token punctuation">.</span>4/bin/mysqld <span class="token property">--initialize-insecure</span> <span class="token constant">--basedir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/mysql-8.4</span> <span class="token constant">--datadir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/data/s1</span>
mysql-8<span class="token punctuation">.</span>4/bin/mysqld <span class="token property">--initialize-insecure</span> <span class="token constant">--basedir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/mysql-8.4</span> <span class="token constant">--datadir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/data/s2</span>
mysql-8<span class="token punctuation">.</span>4/bin/mysqld <span class="token property">--initialize-insecure</span> <span class="token constant">--basedir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/mysql-8.4</span> <span class="token constant">--datadir</span><span class="token attr-value"><span class="token punctuation">=</span>$PWD/data/s3</span></code></pre>
</div>
<p>
Inside
<code class="literal">
data/s1
</code>
,
<code class="literal">
data/s2
</code>
,
<code class="literal">
data/s3
</code>
is an initialized data directory,
containing the mysql system database and related tables and much
more. To learn more about the initialization procedure, see
<a class="xref" href="data-directory-initialization.html" title="2.9.1 Initializing the Data Directory">
Section 2.9.1, “Initializing the Data Directory”
</a>
.
</p>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
Do not use
<code class="literal">
-initialize-insecure
</code>
in production
environments, it is only used here to simplify the tutorial. For
more information on security settings, see
<a class="xref" href="group-replication-security.html" title="20.6 Group Replication Security">
Section 20.6, “Group Replication Security”
</a>
.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="configure-local-group-members">
</a>
Configuration of Local Group Replication Members
</h4>
</div>
</div>
</div>
<p>
When you are following
<a class="xref" href="group-replication-configuring-instances.html" title="20.2.1.2 Configuring an Instance for Group Replication">
Section 20.2.1.2, “Configuring an Instance for Group Replication”
</a>
, you
need to add configuration for the data directories added in the
previous section. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa20631903"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span>
<span class="token comment" spellcheck="true"># server configuration</span>
<span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span><full_path_to_data>/data/s1</span>
<span class="token constant">basedir</span><span class="token attr-value"><span class="token punctuation">=</span><full_path_to_bin>/mysql-8.4/</span>
<span class="token constant">port</span><span class="token attr-value"><span class="token punctuation">=</span>24801</span>
<span class="token constant">socket</span><span class="token attr-value"><span class="token punctuation">=</span><full_path_to_sock_dir>/s1.sock</span></code></pre>
</div>
<p>
These settings configure MySQL server to use the data directory
created earlier and which port the server should open and start
listening for incoming connections.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The non-default port of 24801 is used because in this tutorial
the three server instances use the same hostname. In a setup
with three different machines this would not be required.
</p>
</div>
<p>
Group Replication requires a network connection between the
members, which means that each member must be able to resolve
the network address of all of the other members. For example in
this tutorial all three instances run on one machine, so to
ensure that the members can contact each other you could add a
line to the option file such as
<a class="link" href="replication-options-replica.html#sysvar_report_host">
<code class="literal">
report_host=127.0.0.1
</code>
</a>
.
</p>
<p>
Then each member needs to be able to connect to the other
members on their
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_local_address">
<code class="literal">
group_replication_local_address
</code>
</a>
.
For example in the option file of member s1 add:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa38560065"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">group_replication_local_address</span><span class="token attr-value"><span class="token punctuation">=</span> "127.0.0.1:24901"</span>
<span class="token constant">group_replication_group_seeds</span><span class="token attr-value"><span class="token punctuation">=</span> "127.0.0.1:24901,127.0.0.1:24902,127.0.0.1:24903"</span></code></pre>
</div>
<p>
This configures s1 to use port 24901 for internal group
communication with seed members. For each server instance you
want to add to the group, make these changes in the option file
of the member. For each member you must ensure a unique address
is specified, so use a unique port per instance for
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_local_address">
<code class="literal">
group_replication_local_address
</code>
</a>
.
Usually you want all members to be able to serve as seeds for
members that are joining the group and have not got the
transactions processed by the group. In this case, add all of
the ports to
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_seeds">
<code class="literal">
group_replication_group_seeds
</code>
</a>
as shown above.
</p>
<p>
The remaining steps of
<a class="xref" href="group-replication-deploying-in-single-primary-mode.html" title="20.2.1 Deploying Group Replication in Single-Primary Mode">
Section 20.2.1, “Deploying Group Replication in Single-Primary Mode”
</a>
apply equally to a group which you have deployed locally in this
way.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/security-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="security-options">
</a>
8.1.4 Security-Related mysqld Options and Variables
</h3>
</div>
</div>
</div>
<p>
The following table shows
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
options and
system variables that affect security. For descriptions of each of
these, see
<a class="xref" href="server-options.html" title="7.1.7 Server Command Options">
Section 7.1.7, “Server Command Options”
</a>
, and
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
.
</p>
<div class="table">
<a name="idm46045252704464">
</a>
<p class="title">
<b>
Table 8.1 Security Option and Variable Summary
</b>
</p>
<div class="table-contents">
<table frame="box" rules="all" summary="Security-related command-line options and system variables.">
<colgroup>
<col style="width: 20%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Name
</th>
<th scope="col">
Cmd-Line
</th>
<th scope="col">
Option File
</th>
<th scope="col">
System Var
</th>
<th scope="col">
Status Var
</th>
<th scope="col">
Var Scope
</th>
<th scope="col">
Dynamic
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<a class="link" href="server-options.html#option_mysqld_allow-suspicious-udfs">
allow-suspicious-udfs
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-system-variables.html#sysvar_automatic_sp_privileges">
automatic_sp_privileges
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-options.html#option_mysqld_chroot">
chroot
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-system-variables.html#sysvar_local_infile">
local_infile
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-options.html#option_mysqld_safe-user-create">
safe-user-create
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-system-variables.html#sysvar_secure_file_priv">
secure_file_priv
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-options.html#option_mysqld_skip-grant-tables">
skip-grant-tables
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-system-variables.html#sysvar_skip_name_resolve">
skip_name_resolve
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-system-variables.html#sysvar_skip_networking">
skip_networking
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="server-options.html#option_mysqld_skip-show-database">
skip_show_database
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</div>
<div class="table-contents">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;">
<thead>
<tr>
<th scope="col" style="width: 176.875px;">
Name
</th>
<th scope="col" style="width: 96.6562px;">
Cmd-Line
</th>
<th scope="col" style="width: 99.25px;">
Option File
</th>
<th scope="col" style="width: 99.7812px;">
System Var
</th>
<th scope="col" style="width: 98.4531px;">
Status Var
</th>
<th scope="col" style="width: 97.6406px;">
Var Scope
</th>
<th scope="col" style="width: 69.3438px;">
Dynamic
</th>
</tr>
</thead>
</table>
</div>
</div>
<br class="table-break"/>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/json-modification-functions.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="json-modification-functions">
</a>
14.17.4 Functions That Modify JSON Values
</h3>
</div>
</div>
</div>
<p>
The functions in this section modify JSON values and return the
result.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a name="function_json-array-append">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-array-append">
<code class="literal">
JSON_ARRAY_APPEND(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045195136288">
</a>
<p>
Appends values to the end of the indicated arrays within a
JSON document and returns the result. Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard.
</p>
<p>
The path-value pairs are evaluated left to right. The document
produced by evaluating one pair becomes the new value against
which the next pair is evaluated.
</p>
<p>
If a path selects a scalar or object value, that value is
autowrapped within an array and the new value is added to that
array. Pairs for which the path does not identify any value in
the JSON document are ignored.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa51909472"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'["a", ["b", "c"], "d"]'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[1]'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$[1]', 1) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", ["b", "c", 1], "d"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[0]'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$[0]', 2) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [["a", 2], ["b", "c"], "d"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[1][0]'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$[1][0]', 3) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", [["b", 3], "c"], "d"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'{"a": 1, "b": [2, 3], "c": 4}'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.b'</span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$.b', 'x') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1, "b": [2, 3, "x"], "c": 4} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'y'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$.c', 'y') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1, "b": [2, 3], "c": [4, "y"]} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'{"a": 1}'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_APPEND</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$'</span><span class="token punctuation">,</span> <span class="token string">'z'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_APPEND(@j, '$', 'z') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [{"a": 1}, "z"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-array-insert">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-array-insert">
<code class="literal">
JSON_ARRAY_INSERT(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045195110576">
</a>
<p>
Updates a JSON document, inserting into an array within the
document and returning the modified document. Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard or does
not end with an array element identifier.
</p>
<p>
The path-value pairs are evaluated left to right. The document
produced by evaluating one pair becomes the new value against
which the next pair is evaluated.
</p>
<p>
Pairs for which the path does not identify any array in the
JSON document are ignored. If a path identifies an array
element, the corresponding value is inserted at that element
position, shifting any following values to the right. If a
path identifies an array position past the end of an array,
the value is inserted at the end of the array.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3415362"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'["a", {"b": [1, 2]}, [3, 4]]'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[1]'</span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_INSERT(@j, '$[1]', 'x') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", "x", {"b": [1, 2]}, [3, 4]] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[100]'</span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_INSERT(@j, '$[100]', 'x') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", {"b": [1, 2]}, [3, 4], "x"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[1].b[0]'</span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_INSERT(@j, '$[1].b[0]', 'x') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", {"b": ["x", 1, 2]}, [3, 4]] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[2][1]'</span><span class="token punctuation">,</span> <span class="token string">'y'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_INSERT(@j, '$[2][1]', 'y') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", {"b": [1, 2]}, [3, "y", 4]] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_ARRAY_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[0]'</span><span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">,</span> <span class="token string">'$[2][1]'</span><span class="token punctuation">,</span> <span class="token string">'y'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_ARRAY_INSERT(@j, '$[0]', 'x', '$[2][1]', 'y') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["x", "a", {"b": [1, 2]}, [3, 4]] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
Earlier modifications affect the positions of the following
elements in the array, so subsequent paths in the same
<a class="link" href="json-modification-functions.html#function_json-array-insert">
<code class="literal">
JSON_ARRAY_INSERT()
</code>
</a>
call should
take this into account. In the final example, the second path
inserts nothing because the path no longer matches anything
after the first insert.
</p>
</li>
<li class="listitem">
<a name="function_json-insert">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-insert">
<code class="literal">
JSON_INSERT(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045195085088">
</a>
<p>
Inserts data into a JSON document and returns the result.
Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard.
</p>
<p>
The path-value pairs are evaluated left to right. The document
produced by evaluating one pair becomes the new value against
which the next pair is evaluated.
</p>
<p>
A path-value pair for an existing path in the document is
ignored and does not overwrite the existing document value. A
path-value pair for a nonexisting path in the document adds
the value to the document if the path identifies one of these
types of values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
A member not present in an existing object. The member is
added to the object and associated with the new value.
</p>
</li>
<li class="listitem">
<p>
A position past the end of an existing array. The array is
extended with the new value. If the existing value is not
an array, it is autowrapped as an array, then extended
with the new value.
</p>
</li>
</ul>
</div>
<p>
Otherwise, a path-value pair for a nonexisting path in the
document is ignored and has no effect.
</p>
<p>
For a comparison of
<a class="link" href="json-modification-functions.html#function_json-insert">
<code class="literal">
JSON_INSERT()
</code>
</a>
,
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE()
</code>
</a>
, and
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
, see the discussion
of
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa87073628"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'{ "a": 1, "b": [2, 3]}'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_INSERT(@j, '$.a', 10, '$.c', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1, "b": [2, 3], "c": "[true, false]"} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The third and final value listed in the result is a quoted
string and not an array like the second one (which is not
quoted in the output); no casting of values to the JSON type
is performed. To insert the array as an array, you must
perform such casts explicitly, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa66919154"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token function">CAST</span><span class="token punctuation">(</span><span class="token string">'[true, false]'</span> <span class="token keyword">AS</span> <span class="token datatype">JSON</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_INSERT(@j, '$.a', 10, '$.c', CAST('[true, false]' AS JSON)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1, "b": [2, 3], "c": [true, false]} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">1 row in set (0.00 sec)</span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-merge">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-merge">
<code class="literal">
JSON_MERGE(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
json_doc
</code>
</em>
[,
<em class="replaceable">
<code>
json_doc
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045195055808">
</a>
<p>
Deprecated synonym for
<code class="literal">
JSON_MERGE_PRESERVE()
</code>
.
</p>
</li>
<li class="listitem">
<a name="function_json-merge-patch">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-merge-patch">
<code class="literal">
JSON_MERGE_PATCH(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
json_doc
</code>
</em>
[,
<em class="replaceable">
<code>
json_doc
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045195046096">
</a>
<p>
Performs an
<a class="ulink" href="https://tools.ietf.org/html/rfc7396" target="_blank">
RFC
7396
</a>
compliant merge of two or more JSON documents and
returns the merged result, without preserving members having
duplicate keys. Raises an error if at least one of the
documents passed as arguments to this function is not valid.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
For an explanation and example of the differences between
this function and
<code class="literal">
JSON_MERGE_PRESERVE()
</code>
,
see
<a class="xref" href="json-modification-functions.html#json-merge-patch-json-merge-preserve-compared" title="JSON_MERGE_PATCH() compared with JSON_MERGE_PRESERVE()">
JSON_MERGE_PATCH() compared with JSON_MERGE_PRESERVE()
</a>
.
</p>
</div>
<p>
<code class="literal">
JSON_MERGE_PATCH()
</code>
performs a merge as
follows:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
If the first argument is not an object, the result of the
merge is the same as if an empty object had been merged
with the second argument.
</p>
</li>
<li class="listitem">
<p>
If the second argument is not an object, the result of the
merge is the second argument.
</p>
</li>
<li class="listitem">
<p>
If both arguments are objects, the result of the merge is
an object with the following members:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
All members of the first object which do not have a
corresponding member with the same key in the second
object.
</p>
</li>
<li class="listitem">
<p>
All members of the second object which do not have a
corresponding key in the first object, and whose value
is not the JSON
<code class="literal">
null
</code>
literal.
</p>
</li>
<li class="listitem">
<p>
All members with a key that exists in both the first
and the second object, and whose value in the second
object is not the JSON
<code class="literal">
null
</code>
literal. The values of these members are the results
of recursively merging the value in the first object
with the value in the second object.
</p>
</li>
</ul>
</div>
</li>
</ol>
</div>
<p>
For additional information, see
<a class="xref" href="json.html#json-normalization" title="Normalization, Merging, and Autowrapping of JSON Values">
Normalization, Merging, and Autowrapping of JSON Values
</a>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa80502412"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'[1, 2]'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('[1, 2]', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [true, false] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'{"name": "x"}'</span><span class="token punctuation">,</span> <span class="token string">'{"id": 47}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('{"name": "x"}', '{"id": 47}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"id": 47, "name": "x"} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'1'</span><span class="token punctuation">,</span> <span class="token string">'true'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('1', 'true') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> true <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'[1, 2]'</span><span class="token punctuation">,</span> <span class="token string">'{"id": 47}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('[1, 2]', '{"id": 47}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"id": 47} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'{ "a": 1, "b":2 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token string">'{ "a": 3, "c":4 }'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('{ "a": 1, "b":2 }','{ "a": 3, "c":4 }') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 3, "b": 2, "c": 4} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'{ "a": 1, "b":2 }'</span><span class="token punctuation">,</span><span class="token string">'{ "a": 3, "c":4 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token string">'{ "a": 5, "d":6 }'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('{ "a": 1, "b":2 }','{ "a": 3, "c":4 }','{ "a": 5, "d":6 }') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 5, "b": 2, "c": 4, "d": 6} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
You can use this function to remove a member by specifying
<code class="literal">
null
</code>
as the value of the same member in the
second argument, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67123495"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'{"a":1, "b":2}'</span><span class="token punctuation">,</span> <span class="token string">'{"b":null}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('{"a":1, "b":2}', '{"b":null}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This example shows that the function operates in a recursive
fashion; that is, values of members are not limited to
scalars, but rather can themselves be JSON documents:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6795782"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token string">'{"a":{"x":1}}'</span><span class="token punctuation">,</span> <span class="token string">'{"a":{"y":2}}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PATCH('{"a":{"x":1}}', '{"a":{"y":2}}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": {"x": 1, "y": 2}} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
<a name="json-merge-patch-json-merge-preserve-compared">
</a>
<b>
JSON_MERGE_PATCH() compared with JSON_MERGE_PRESERVE().
</b>
The behavior of
<code class="literal">
JSON_MERGE_PATCH()
</code>
is the
same as that of
<a class="link" href="json-modification-functions.html#function_json-merge-preserve">
<code class="literal">
JSON_MERGE_PRESERVE()
</code>
</a>
, with
the following two exceptions:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<code class="literal">
JSON_MERGE_PATCH()
</code>
removes any member
in the first object with a matching key in the second
object, provided that the value associated with the key in
the second object is not JSON
<code class="literal">
null
</code>
.
</p>
</li>
<li class="listitem">
<p>
If the second object has a member with a key matching a
member in the first object,
<code class="literal">
JSON_MERGE_PATCH()
</code>
<span class="emphasis">
<em>
replaces
</em>
</span>
the value in the first
object with the value in the second object, whereas
<code class="literal">
JSON_MERGE_PRESERVE()
</code>
<span class="emphasis">
<em>
appends
</em>
</span>
the second value to the first
value.
</p>
</li>
</ul>
</div>
<p>
This example compares the results of merging the same 3 JSON
objects, each having a matching key
<code class="literal">
"a"
</code>
,
with each of these two functions:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa36715400"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@x</span> <span class="token operator">=</span> <span class="token string">'{ "a": 1, "b": 2 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token variable">@y</span> <span class="token operator">=</span> <span class="token string">'{ "a": 3, "c": 4 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token variable">@z</span> <span class="token operator">=</span> <span class="token string">'{ "a": 5, "d": 6 }'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PATCH</span><span class="token punctuation">(</span><span class="token variable">@x</span><span class="token punctuation">,</span> <span class="token variable">@y</span><span class="token punctuation">,</span> <span class="token variable">@z</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> Patch<span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token variable">@x</span><span class="token punctuation">,</span> <span class="token variable">@y</span><span class="token punctuation">,</span> <span class="token variable">@z</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">Preserve</span>\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Patch<span class="token punctuation">:</span> {"a"<span class="token punctuation">:</span> 5, "b"<span class="token punctuation">:</span> 2, "c"<span class="token punctuation">:</span> 4, "d"<span class="token punctuation">:</span> 6}
Preserve<span class="token punctuation">:</span> {"a"<span class="token punctuation">:</span> [1, 3, 5], "b"<span class="token punctuation">:</span> 2, "c"<span class="token punctuation">:</span> 4, "d"<span class="token punctuation">:</span> 6}</span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-merge-preserve">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-merge-preserve">
<code class="literal">
JSON_MERGE_PRESERVE(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
json_doc
</code>
</em>
[,
<em class="replaceable">
<code>
json_doc
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045194990304">
</a>
<p>
Merges two or more JSON documents and returns the merged
result. Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if any argument is
not a valid JSON document.
</p>
<p>
Merging takes place according to the following rules. For
additional information, see
<a class="xref" href="json.html#json-normalization" title="Normalization, Merging, and Autowrapping of JSON Values">
Normalization, Merging, and Autowrapping of JSON Values
</a>
.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Adjacent arrays are merged to a single array.
</p>
</li>
<li class="listitem">
<p>
Adjacent objects are merged to a single object.
</p>
</li>
<li class="listitem">
<p>
A scalar value is autowrapped as an array and merged as an
array.
</p>
</li>
<li class="listitem">
<p>
An adjacent array and object are merged by autowrapping
the object as an array and merging the two arrays.
</p>
</li>
</ul>
</div>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa15678876"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'[1, 2]'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('[1, 2]', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [1, 2, true, false] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'{"name": "x"}'</span><span class="token punctuation">,</span> <span class="token string">'{"id": 47}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('{"name": "x"}', '{"id": 47}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"id": 47, "name": "x"} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'1'</span><span class="token punctuation">,</span> <span class="token string">'true'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('1', 'true') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [1, true] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'[1, 2]'</span><span class="token punctuation">,</span> <span class="token string">'{"id": 47}'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('[1, 2]', '{"id": 47}') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [1, 2, {"id": 47}] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'{ "a": 1, "b": 2 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token string">'{ "a": 3, "c": 4 }'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('{ "a": 1, "b": 2 }','{ "a": 3, "c":4 }') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": [1, 3], "b": 2, "c": 4} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_MERGE_PRESERVE</span><span class="token punctuation">(</span><span class="token string">'{ "a": 1, "b": 2 }'</span><span class="token punctuation">,</span><span class="token string">'{ "a": 3, "c": 4 }'</span><span class="token punctuation">,</span>
<span class="token operator">></span> <span class="token string">'{ "a": 5, "d": 6 }'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_MERGE_PRESERVE('{ "a": 1, "b": 2 }','{ "a": 3, "c": 4 }','{ "a": 5, "d": 6 }') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": [1, 3, 5], "b": 2, "c": 4, "d": 6} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This function is similar to but differs from
<a class="link" href="json-modification-functions.html#function_json-merge-patch">
<code class="literal">
JSON_MERGE_PATCH()
</code>
</a>
in
significant respects; see
<a class="xref" href="json-modification-functions.html#json-merge-patch-json-merge-preserve-compared" title="JSON_MERGE_PATCH() compared with JSON_MERGE_PRESERVE()">
JSON_MERGE_PATCH() compared with JSON_MERGE_PRESERVE()
</a>
,
for more information.
</p>
</li>
<li class="listitem">
<a name="function_json-remove">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-remove">
<code class="literal">
JSON_REMOVE(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045194961376">
</a>
<p>
Removes data from a JSON document and returns the result.
Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or is
<code class="literal">
$
</code>
or
contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard.
</p>
<p>
The
<em class="replaceable">
<code>
path
</code>
</em>
arguments are evaluated
left to right. The document produced by evaluating one path
becomes the new value against which the next path is
evaluated.
</p>
<p>
It is not an error if the element to be removed does not exist
in the document; in that case, the path does not affect the
document.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa8804803"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'["a", ["b", "c"], "d"]'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_REMOVE</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$[1]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_REMOVE(@j, '$[1]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ["a", "d"] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-replace">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045194941872">
</a>
<p>
Replaces existing values in a JSON document and returns the
result. Returns
<code class="literal">
NULL
</code>
if any argument is
<code class="literal">
NULL
</code>
. An error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard.
</p>
<p>
The path-value pairs are evaluated left to right. The document
produced by evaluating one pair becomes the new value against
which the next pair is evaluated.
</p>
<p>
A path-value pair for an existing path in the document
overwrites the existing document value with the new value. A
path-value pair for a nonexisting path in the document is
ignored and has no effect.
</p>
<p>
The optimizer can perform a partial, in-place update of a
<code class="literal">
JSON
</code>
column instead of removing the old
document and writing the new document in its entirety to the
column. This optimization can be performed for an update
statement that uses the
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE()
</code>
</a>
function and
meets the conditions outlined in
<a class="xref" href="json.html#json-partial-updates" title="Partial Updates of JSON Values">
Partial Updates of JSON Values
</a>
.
</p>
<p>
For a comparison of
<a class="link" href="json-modification-functions.html#function_json-insert">
<code class="literal">
JSON_INSERT()
</code>
</a>
,
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE()
</code>
</a>
, and
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
, see the discussion
of
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4283515"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'{ "a": 1, "b": [2, 3]}'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_REPLACE</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_REPLACE(@j, '$.a', 10, '$.c', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 10, "b": [2, 3]} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-set">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET(
<em class="replaceable">
<code>
json_doc
</code>
</em>
,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
[,
<em class="replaceable">
<code>
path
</code>
</em>
,
<em class="replaceable">
<code>
val
</code>
</em>
] ...)
</code>
</a>
</p>
<a class="indexterm" name="idm46045194914432">
</a>
<p>
Inserts or updates data in a JSON document and returns the
result. Returns
<code class="literal">
NULL
</code>
if
<em class="replaceable">
<code>
json_doc
</code>
</em>
or
<em class="replaceable">
<code>
path
</code>
</em>
is
<code class="literal">
NULL
</code>
, or
if
<em class="replaceable">
<code>
path
</code>
</em>
, when given, does not
locate an object. Otherwise, an error occurs if the
<em class="replaceable">
<code>
json_doc
</code>
</em>
argument is not a valid
JSON document or any
<em class="replaceable">
<code>
path
</code>
</em>
argument
is not a valid path expression or contains a
<code class="literal">
*
</code>
or
<code class="literal">
**
</code>
wildcard.
</p>
<p>
The path-value pairs are evaluated left to right. The document
produced by evaluating one pair becomes the new value against
which the next pair is evaluated.
</p>
<p>
A path-value pair for an existing path in the document
overwrites the existing document value with the new value. A
path-value pair for a nonexisting path in the document adds
the value to the document if the path identifies one of these
types of values:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
A member not present in an existing object. The member is
added to the object and associated with the new value.
</p>
</li>
<li class="listitem">
<p>
A position past the end of an existing array. The array is
extended with the new value. If the existing value is not
an array, it is autowrapped as an array, then extended
with the new value.
</p>
</li>
</ul>
</div>
<p>
Otherwise, a path-value pair for a nonexisting path in the
document is ignored and has no effect.
</p>
<p>
The optimizer can perform a partial, in-place update of a
<code class="literal">
JSON
</code>
column instead of removing the old
document and writing the new document in its entirety to the
column. This optimization can be performed for an update
statement that uses the
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
function and meets
the conditions outlined in
<a class="xref" href="json.html#json-partial-updates" title="Partial Updates of JSON Values">
Partial Updates of JSON Values
</a>
.
</p>
<p>
The
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
,
<a class="link" href="json-modification-functions.html#function_json-insert">
<code class="literal">
JSON_INSERT()
</code>
</a>
, and
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE()
</code>
</a>
functions are
related:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<a class="link" href="json-modification-functions.html#function_json-set">
<code class="literal">
JSON_SET()
</code>
</a>
replaces
existing values and adds nonexisting values.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="json-modification-functions.html#function_json-insert">
<code class="literal">
JSON_INSERT()
</code>
</a>
inserts
values without replacing existing values.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="json-modification-functions.html#function_json-replace">
<code class="literal">
JSON_REPLACE()
</code>
</a>
replaces
<span class="emphasis">
<em>
only
</em>
</span>
existing values.
</p>
</li>
</ul>
</div>
<p>
The following examples illustrate these differences, using one
path that does exist in the document (
<code class="literal">
$.a
</code>
)
and another that does not exist (
<code class="literal">
$.c
</code>
):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa97590577"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'{ "a": 1, "b": [2, 3]}'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_SET</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_SET(@j, '$.a', 10, '$.c', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 10, "b": [2, 3], "c": "[true, false]"} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_INSERT</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_INSERT(@j, '$.a', 10, '$.c', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 1, "b": [2, 3], "c": "[true, false]"} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_REPLACE</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token string">'$.a'</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'$.c'</span><span class="token punctuation">,</span> <span class="token string">'[true, false]'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_REPLACE(@j, '$.a', 10, '$.c', '[true, false]') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> {"a": 10, "b": [2, 3]} <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_json-unquote">
</a>
<p>
<a class="link" href="json-modification-functions.html#function_json-unquote">
<code class="literal">
JSON_UNQUOTE(
<em class="replaceable">
<code>
json_val
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045194874112">
</a>
<p>
Unquotes JSON value and returns the result as a
<code class="literal">
utf8mb4
</code>
string. Returns
<code class="literal">
NULL
</code>
if the argument is
<code class="literal">
NULL
</code>
. An error occurs if the value starts
and ends with double quotes but is not a valid JSON string
literal.
</p>
<p>
Within a string, certain sequences have special meaning unless
the
<a class="link" href="sql-mode.html#sqlmode_no_backslash_escapes">
<code class="literal">
NO_BACKSLASH_ESCAPES
</code>
</a>
SQL
mode is enabled. Each of these sequences begins with a
backslash (
<code class="literal">
\
</code>
), known as the
<span class="emphasis">
<em>
escape character
</em>
</span>
. MySQL recognizes the
escape sequences shown in
<a class="xref" href="json-modification-functions.html#json-unquote-character-escape-sequences" title="Table 14.23 JSON_UNQUOTE() Special Character Escape Sequences">
Table 14.23, “JSON_UNQUOTE() Special Character Escape Sequences”
</a>
. For
all other escape sequences, backslash is ignored. That is, the
escaped character is interpreted as if it was not escaped. For
example,
<code class="literal">
\x
</code>
is just
<code class="literal">
x
</code>
.
These sequences are case-sensitive. For example,
<code class="literal">
\b
</code>
is interpreted as a backspace, but
<code class="literal">
\B
</code>
is interpreted as
<code class="literal">
B
</code>
.
</p>
<div class="table">
<a name="json-unquote-character-escape-sequences">
</a>
<p class="title">
<b>
Table 14.23 JSON_UNQUOTE() Special Character Escape Sequences
</b>
</p>
<div class="table-contents">
<table>
<colgroup>
<col style="width: 15%"/>
<col style="width: 85%"/>
</colgroup>
<thead>
<tr>
<th>
Escape Sequence
</th>
<th>
Character Represented by Sequence
</th>
</tr>
</thead>
<tbody>
<tr>
<td>
<code class="literal">
\"
</code>
<a class="indexterm" name="idm46045194854336">
</a>
<a class="indexterm" name="idm46045194853392">
</a>
</td>
<td>
A double quote (
<code class="literal">
"
</code>
) character
</td>
</tr>
<tr>
<td>
<code class="literal">
\b
</code>
<a class="indexterm" name="idm46045194849216">
</a>
<a class="indexterm" name="idm46045194848272">
</a>
</td>
<td>
A backspace character
</td>
</tr>
<tr>
<td>
<code class="literal">
\f
</code>
<a class="indexterm" name="idm46045194844736">
</a>
<a class="indexterm" name="idm46045194843792">
</a>
</td>
<td>
A formfeed character
</td>
</tr>
<tr>
<td>
<code class="literal">
\n
</code>
<a class="indexterm" name="idm46045194840304">
</a>
<a class="indexterm" name="idm46045194839360">
</a>
<a class="indexterm" name="idm46045194838416">
</a>
<a class="indexterm" name="idm46045194837472">
</a>
</td>
<td>
A newline (linefeed) character
</td>
</tr>
<tr>
<td>
<code class="literal">
\r
</code>
<a class="indexterm" name="idm46045194833968">
</a>
<a class="indexterm" name="idm46045194833024">
</a>
<a class="indexterm" name="idm46045194832080">
</a>
</td>
<td>
A carriage return character
</td>
</tr>
<tr>
<td>
<code class="literal">
\t
</code>
<a class="indexterm" name="idm46045194828576">
</a>
<a class="indexterm" name="idm46045194827632">
</a>
</td>
<td>
A tab character
</td>
</tr>
<tr>
<td>
<code class="literal">
\\
</code>
<a class="indexterm" name="idm46045194824144">
</a>
<a class="indexterm" name="idm46045194823200">
</a>
</td>
<td>
A backslash (
<code class="literal">
\
</code>
) character
</td>
</tr>
<tr>
<td>
<code class="literal">
\u
<em class="replaceable">
<code>
XXXX
</code>
</em>
</code>
<a class="indexterm" name="idm46045194818736">
</a>
<a class="indexterm" name="idm46045194817792">
</a>
</td>
<td>
UTF-8 bytes for Unicode value
<em class="replaceable">
<code>
XXXX
</code>
</em>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<br class="table-break"/>
<p>
Two simple examples of the use of this function are shown
here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa8739506"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'"abc"'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token function">JSON_UNQUOTE</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> @j <span class="token punctuation">|</span> JSON_UNQUOTE(@j) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> "abc" <span class="token punctuation">|</span> abc <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@j</span> <span class="token operator">=</span> <span class="token string">'[1, 2, 3]'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@j</span><span class="token punctuation">,</span> <span class="token function">JSON_UNQUOTE</span><span class="token punctuation">(</span><span class="token variable">@j</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> @j <span class="token punctuation">|</span> JSON_UNQUOTE(@j) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> [1, 2, 3] <span class="token punctuation">|</span> [1, 2, 3] <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The following set of examples shows how
<code class="literal">
JSON_UNQUOTE
</code>
handles escapes with
<a class="link" href="sql-mode.html#sqlmode_no_backslash_escapes">
<code class="literal">
NO_BACKSLASH_ESCAPES
</code>
</a>
disabled and enabled:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa17156444"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@@sql_mode</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> @@sql_mode <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_UNQUOTE</span><span class="token punctuation">(</span><span class="token string">'"\\t\\u0032"'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_UNQUOTE('"\\t\\u0032"') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@@sql_mode</span> <span class="token operator">=</span> <span class="token string">'NO_BACKSLASH_ESCAPES'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_UNQUOTE</span><span class="token punctuation">(</span><span class="token string">'"\\t\\u0032"'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_UNQUOTE('"\\t\\u0032"') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> \t\u0032 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">JSON_UNQUOTE</span><span class="token punctuation">(</span><span class="token string">'"\t\u0032"'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> JSON_UNQUOTE('"\t\u0032"') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/alter-procedure.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="alter-procedure">
</a>
15.1.7 ALTER PROCEDURE Statement
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045189615696">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa96833201"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">PROCEDURE</span> <em class="replaceable">proc_name</em> <span class="token punctuation">[</span><em class="replaceable">characteristic</em> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span>
<em class="replaceable">characteristic</em>: {
<span class="token keyword">COMMENT</span> <span class="token string">'<em class="replaceable">string</em>'</span>
<span class="token operator">|</span> <span class="token keyword">LANGUAGE</span> <span class="token keyword">SQL</span>
<span class="token operator">|</span> { <span class="token keyword">CONTAINS</span> <span class="token keyword">SQL</span> <span class="token operator">|</span> <span class="token keyword">NO</span> <span class="token keyword">SQL</span> <span class="token operator">|</span> <span class="token keyword">READS</span> <span class="token keyword">SQL</span> <span class="token keyword">DATA</span> <span class="token operator">|</span> <span class="token keyword">MODIFIES</span> <span class="token keyword">SQL</span> <span class="token keyword">DATA</span> }
<span class="token operator">|</span> <span class="token keyword">SQL</span> <span class="token keyword">SECURITY</span> { <span class="token keyword">DEFINER</span> <span class="token operator">|</span> <span class="token keyword">INVOKER</span> }
}</code></pre>
</div>
<p>
This statement can be used to change the characteristics of a
stored procedure. More than one change may be specified in an
<a class="link" href="alter-procedure.html" title="15.1.7 ALTER PROCEDURE Statement">
<code class="literal">
ALTER PROCEDURE
</code>
</a>
statement. However,
you cannot change the parameters or body of a stored procedure
using this statement; to make such changes, you must drop and
re-create the procedure using
<a class="link" href="drop-procedure.html" title="15.1.29 DROP PROCEDURE and DROP FUNCTION Statements">
<code class="literal">
DROP
PROCEDURE
</code>
</a>
and
<a class="link" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements">
<code class="literal">
CREATE
PROCEDURE
</code>
</a>
.
</p>
<p>
You must have the
<a class="link" href="privileges-provided.html#priv_alter-routine">
<code class="literal">
ALTER ROUTINE
</code>
</a>
privilege for the procedure. By default, that privilege is granted
automatically to the procedure creator. This behavior can be
changed by disabling the
<a class="link" href="server-system-variables.html#sysvar_automatic_sp_privileges">
<code class="literal">
automatic_sp_privileges
</code>
</a>
system
variable. See
<a class="xref" href="stored-routines-privileges.html" title="27.2.2 Stored Routines and MySQL Privileges">
Section 27.2.2, “Stored Routines and MySQL Privileges”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/group-replication-performance.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="group-replication-performance">
</a>
20.7 Group Replication Performance and Troubleshooting
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="group-replication-fine-tuning-the-group-communication-thread.html">
20.7.1 Fine Tuning the Group Communication Thread
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-flow-control.html">
20.7.2 Flow Control
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-single-consensus-leader.html">
20.7.3 Single Consensus Leader
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-message-compression.html">
20.7.4 Message Compression
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-performance-message-fragmentation.html">
20.7.5 Message Fragmentation
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-performance-xcom-cache.html">
20.7.6 XCom Cache Management
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-responses-failure.html">
20.7.7 Responses to Failure Detection and Network Partitioning
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="group-replication-network-partitioning.html">
20.7.8 Handling a Network Partition and Loss of Quorum
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="mysql-gr-memory-monitoring-ps-instruments.html">
20.7.9 Monitoring Group Replication Memory Usage with Performance Schema Memory
Instrumentation
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045132245424">
</a>
<a class="indexterm" name="idm46045132243936">
</a>
<p>
Group Replication is designed to create fault-tolerant systems with
built-in failure detection and automated recovery. If a member
server instance leaves voluntarily or stops communicating with the
group, the remaining members agree a reconfiguration of the group
between themselves, and choose a new primary if needed. Expelled
members automatically attempt to rejoin the group, and are brought
up to date by distributed recovery. If a group experiences a level
of difficulties such that it cannot contact a majority of its
members in order to agree on a decision, it identifies itself as
having lost quorum and stops processing transactions. Group
Replication also has built-in mechanisms and settings to help the
group adapt to and manage variations in workload and message size,
and stay within the limitations of the underlying system and
networking resources.
</p>
<p>
The default settings for Group Replication’s system variables are
designed to maximize a group’s performance and autonomy. The
information in this section is to help you configure a replication
group to optimize the automatic handling of any recurring issues
that you experience on your particular systems, such as transient
network outages or workloads and transactions that exceed a server
instance’s resources.
</p>
<p>
If you find that group members are being expelled and rejoining the
group more frequently than you would like, it is possible that Group
Replication’s default failure detection settings are too sensitive
for your system. This might be the case on slower networks or
machines, networks with a high rate of unexpected transient outages,
or during planned network outages. For advice on dealing with that
situation by adjusting the settings, see
<a class="xref" href="group-replication-responses-failure.html" title="20.7.7 Responses to Failure Detection and Network Partitioning">
Section 20.7.7, “Responses to Failure Detection and Network Partitioning”
</a>
.
</p>
<p>
You should only need to intervene manually in a Group Replication
setup if something happens that the group cannot deal with
automatically. Some key issues that can require administrator
intervention are when a member is in
<code class="literal">
ERROR
</code>
status
and cannot rejoin the group, or when a network partition causes the
group to lose quorum.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If an otherwise correctly functioning and configured member is
unable to join or rejoin the group using distributed recovery,
and remains in
<code class="literal">
ERROR
</code>
status,
<a class="xref" href="group-replication-distributed-recovery-fault.html" title="20.5.4.4 Fault Tolerance for Distributed Recovery">
Section 20.5.4.4, “Fault Tolerance for Distributed Recovery”
</a>
,
explains the possible issues. One likely cause is that the
joining member has extra transactions that are not present on
the existing members of the group. For advice on dealing with
that situation, see
<a class="xref" href="group-replication-gtids.html" title="20.4.1 GTIDs and Group Replication">
Section 20.4.1, “GTIDs and Group Replication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
If a group has lost quorum, this may be due to a network
partition that divides the group into two parts, or possibly due
to the failure of the majority of the servers. For advice on
dealing with that situation, see
<a class="xref" href="group-replication-network-partitioning.html" title="20.7.8 Handling a Network Partition and Loss of Quorum">
Section 20.7.8, “Handling a Network Partition and Loss of Quorum”
</a>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-certificates.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-ndbinfo-certificates">
</a>
25.6.17.6 The ndbinfo certificates Table
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045090442528">
</a>
<p>
The
<code class="literal">
certificates
</code>
table provides information
about the certificates used by nodes connecting with TLS link
encryption (see
<a class="xref" href="mysql-cluster-tls.html" title="25.6.15 TLS Link Encryption for NDB Cluster">
Section 25.6.15, “TLS Link Encryption for NDB Cluster”
</a>
).
</p>
<p>
The
<code class="literal">
certificates
</code>
table contains the following
columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
Node_id
</code>
</p>
<p>
ID of the node where this certificate is found
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
Name
</code>
</p>
<p>
Certificate name
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
Expires
</code>
</p>
<p>
Expiration date, in
<code class="literal">
mm-nnn-yyyy
</code>
format
(for example,
<code class="literal">
18-Dec-2023
</code>
).
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
Serial
</code>
</p>
<p>
Serial number
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/begin-end.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="begin-end">
</a>
15.6.1 BEGIN ... END Compound Statement
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045176510544">
</a>
<a class="indexterm" name="idm46045176509504">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa85547753"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">BEGIN</span>
<span class="token punctuation">[</span><em class="replaceable">statement_list</em><span class="token punctuation">]</span>
<span class="token keyword">END</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span></code></pre>
</div>
<p>
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ... END
</code>
</a>
syntax is used for writing compound statements, which can appear
within stored programs (stored procedures and functions, triggers,
and events). A compound statement can contain multiple statements,
enclosed by the
<code class="literal">
BEGIN
</code>
and
<code class="literal">
END
</code>
keywords.
<em class="replaceable">
<code>
statement_list
</code>
</em>
represents a list of one
or more statements, each terminated by a semicolon
(
<code class="literal">
;
</code>
) statement delimiter. The
<em class="replaceable">
<code>
statement_list
</code>
</em>
itself is optional, so
the empty compound statement (
<code class="literal">
BEGIN END
</code>
) is
legal.
</p>
<p>
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ... END
</code>
</a>
blocks can be nested.
</p>
<p>
Use of multiple statements requires that a client is able to send
statement strings containing the
<code class="literal">
;
</code>
statement
delimiter. In the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
command-line client,
this is handled with the
<code class="literal">
delimiter
</code>
command.
Changing the
<code class="literal">
;
</code>
end-of-statement delimiter (for
example, to
<code class="literal">
//
</code>
) permit
<code class="literal">
;
</code>
to
be used in a program body. For an example, see
<a class="xref" href="stored-programs-defining.html" title="27.1 Defining Stored Programs">
Section 27.1, “Defining Stored Programs”
</a>
.
</p>
<p>
A
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ...
END
</code>
</a>
block can be labeled. See
<a class="xref" href="statement-labels.html" title="15.6.2 Statement Labels">
Section 15.6.2, “Statement Labels”
</a>
.
</p>
<p>
The optional
<code class="literal">
[NOT] ATOMIC
</code>
clause is not
supported. This means that no transactional savepoint is set at
the start of the instruction block and the
<code class="literal">
BEGIN
</code>
clause used in this context has no effect
on the current transaction.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Within all stored programs, the parser treats
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
BEGIN [WORK]
</code>
</a>
as the beginning of a
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ...
END
</code>
</a>
block. To begin a transaction in this context, use
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
START
TRANSACTION
</code>
</a>
instead.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/using-gdb-on-mysqld.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="using-gdb-on-mysqld">
</a>
7.9.1.4 Debugging mysqld under gdb
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045253751296">
</a>
<p>
On most systems you can also start
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
from
<span class="command">
<strong>
gdb
</strong>
</span>
to get more information if
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
crashes.
</p>
<p>
With some older
<span class="command">
<strong>
gdb
</strong>
</span>
versions on Linux you
must use
<code class="literal">
run --one-thread
</code>
if you want to be
able to debug
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
threads. In this case,
you can only have one thread active at a time.
</p>
<p>
NPTL threads (the new thread library on Linux) may cause
problems while running
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
under
<span class="command">
<strong>
gdb
</strong>
</span>
. Some symptoms are:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
hangs during startup (before it
writes
<code class="literal">
ready for connections
</code>
).
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
crashes during a
<code class="literal">
pthread_mutex_lock()
</code>
or
<code class="literal">
pthread_mutex_unlock()
</code>
call.
</p>
</li>
</ul>
</div>
<p>
In this case, you should set the following environment variable
in the shell before starting
<span class="command">
<strong>
gdb
</strong>
</span>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa51494095"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">LD_ASSUME_KERNEL<span class="token attr-value"><span class="token punctuation">=</span>2.4.1</span>
export LD_ASSUME_KERNEL</code></pre>
</div>
<p>
When running
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
under
<span class="command">
<strong>
gdb
</strong>
</span>
, you should disable the stack trace with
<a class="link" href="server-options.html#option_mysqld_skip-stack-trace">
<code class="option">
--skip-stack-trace
</code>
</a>
to be able to
catch segfaults within
<span class="command">
<strong>
gdb
</strong>
</span>
.
</p>
<a class="indexterm" name="idm46045253727712">
</a>
<p>
Use the
<a class="link" href="server-options.html#option_mysqld_gdb">
<code class="option">
--gdb
</code>
</a>
option to
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
to install an interrupt handler for
<code class="literal">
SIGINT
</code>
(needed to stop
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
with
<code class="literal">
^C
</code>
to set
breakpoints) and disable stack tracing and core file handling.
</p>
<p>
It is very hard to debug MySQL under
<span class="command">
<strong>
gdb
</strong>
</span>
if
you do a lot of new connections the whole time as
<span class="command">
<strong>
gdb
</strong>
</span>
does not free the memory for old threads.
You can avoid this problem by starting
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
with
<a class="link" href="server-system-variables.html#sysvar_thread_cache_size">
<code class="literal">
thread_cache_size
</code>
</a>
set to a
value equal to
<a class="link" href="server-system-variables.html#sysvar_max_connections">
<code class="literal">
max_connections
</code>
</a>
+ 1. In most cases just using
<a class="link" href="server-system-variables.html#sysvar_thread_cache_size">
<code class="option">
--thread_cache_size=5'
</code>
</a>
helps a
lot!
</p>
<p>
If you want to get a core dump on Linux if
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
dies with a SIGSEGV signal, you can
start
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
with the
<a class="link" href="server-options.html#option_mysqld_core-file">
<code class="option">
--core-file
</code>
</a>
option. This core
file can be used to make a backtrace that may help you find out
why
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
died:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa44408125"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">gdb</span> mysqld core
<span class="token prompt">gdb></span><span class="token command"> backtrace</span> full
<span class="token prompt">gdb></span><span class="token command"> quit</span></code></pre>
</div>
<p>
See
<a class="xref" href="crashing.html" title="B.3.3.3 What to Do If MySQL Keeps Crashing">
Section B.3.3.3, “What to Do If MySQL Keeps Crashing”
</a>
.
</p>
<p>
If you are using
<span class="command">
<strong>
gdb
</strong>
</span>
on Linux, you should
install a
<code class="filename">
.gdb
</code>
file, with the following
information, in your current directory:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa70984475"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">set print sevenbit off
handle SIGUSR1 nostop noprint
handle SIGUSR2 nostop noprint
handle SIGWAITING nostop noprint
handle SIGLWP nostop noprint
handle SIGPIPE nostop
handle SIGALRM nostop
handle SIGHUP nostop
handle SIGTERM nostop noprint</code></pre>
</div>
<p>
Here is an example how to debug
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa92594841"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">gdb</span> /usr/local/libexec/mysqld
<span class="token prompt">gdb></span><span class="token command"> run</span>
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
backtrace full <span class="token comment" spellcheck="true"># Do this when mysqld crashes</span></code></pre>
</div>
<p>
Include the preceding output in a bug report, which you can file
using the instructions in
<a class="xref" href="bug-reports.html" title="1.6 How to Report Bugs or Problems">
Section 1.6, “How to Report Bugs or Problems”
</a>
.
</p>
<p>
If
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
hangs, you can try to use some
system tools like
<code class="literal">
strace
</code>
or
<code class="literal">
/usr/proc/bin/pstack
</code>
to examine where
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
has hung.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa64324284"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">strace /tmp/log libexec/mysqld</code></pre>
</div>
<a class="indexterm" name="idm46045253692976">
</a>
<a class="indexterm" name="idm46045253691904">
</a>
<a class="indexterm" name="idm46045253690832">
</a>
<a class="indexterm" name="idm46045253689744">
</a>
<p>
If you are using the Perl
<code class="literal">
DBI
</code>
interface, you
can turn on debugging information by using the
<code class="literal">
trace
</code>
method or by setting the
<code class="literal">
DBI_TRACE
</code>
environment variable.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/firewall-reference.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="firewall-reference">
</a>
8.4.7.4 MySQL Enterprise Firewall Reference
</h4>
</div>
</div>
</div>
<p>
The following sections provide a reference to MySQL Enterprise Firewall elements:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-tables" title="MySQL Enterprise Firewall Tables">
MySQL Enterprise Firewall Tables
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-stored-routines" title="MySQL Enterprise Firewall Stored Procedures">
MySQL Enterprise Firewall Stored Procedures
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-functions" title="MySQL Enterprise Firewall Administrative Functions">
MySQL Enterprise Firewall Administrative Functions
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-system-variables" title="MySQL Enterprise Firewall System Variables">
MySQL Enterprise Firewall System Variables
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-status-variables" title="MySQL Enterprise Firewall Status Variables">
MySQL Enterprise Firewall Status Variables
</a>
</p>
</li>
</ul>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="firewall-tables">
</a>
MySQL Enterprise Firewall Tables
</h5>
</div>
</div>
</div>
<p>
MySQL Enterprise Firewall maintains profile information on a per-group and
per-account basis. It uses tables in the firewall database for
persistent storage and
<code class="literal">
INFORMATION_SCHEMA
</code>
or Performance Schema tables to provide views into in-memory
cached data. When enabled, the firewall bases operational
decisions on the cached data. The firewall database can be the
<code class="literal">
mysql
</code>
system database or a custom schema
(see
<a class="xref" href="firewall-installation.html#firewall-install" title="Installing MySQL Enterprise Firewall">
Installing MySQL Enterprise Firewall
</a>
).
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-tables-group" title="Firewall Group Profile Tables">
Firewall Group Profile Tables
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-tables-account" title="Firewall Account Profile Tables">
Firewall Account Profile Tables
</a>
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-tables-group">
</a>
Firewall Group Profile Tables
</h6>
<p>
MySQL Enterprise Firewall maintains group profile information using tables in the
firewall database (
<code class="literal">
mysql
</code>
or custom) for
persistent storage and Performance Schema tables to provide
views into in-memory cached data.
</p>
<p>
Each system and Performance Schema table is accessible only by
accounts that have the
<a class="link" href="privileges-provided.html#priv_select">
<code class="literal">
SELECT
</code>
</a>
privilege for it.
</p>
<p>
The
<code class="literal">
<em class="replaceable">
<code>
default-database
</code>
</em>
.firewall_groups
</code>
table lists names and operational modes of registered firewall
group profiles. The table has the following columns (with the
corresponding Performance Schema
<a class="link" href="performance-schema-firewall-groups-table.html" title="29.12.17.1 The firewall_groups Table">
<code class="literal">
firewall_groups
</code>
</a>
table having
similar but not necessarily identical columns):
</p>
<a class="indexterm" name="idm46045234075856">
</a>
<a class="indexterm" name="idm46045234074816">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
NAME
</code>
</p>
<p>
The group profile name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
MODE
</code>
</p>
<p>
The current operational mode for the profile. Permitted
mode values are
<code class="literal">
OFF
</code>
,
<code class="literal">
DETECTING
</code>
,
<code class="literal">
PROTECTING
</code>
, and
<code class="literal">
RECORDING
</code>
. For details about their
meanings, see
<a class="xref" href="firewall-usage.html#firewall-concepts" title="Firewall Concepts">
Firewall Concepts
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
USERHOST
</code>
</p>
<p>
The training account for the group profile, to be used
when the profile is in
<code class="literal">
RECORDING
</code>
mode.
The value is
<code class="literal">
NULL
</code>
, or a
non-
<code class="literal">
NULL
</code>
account that has the format
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
If the value is
<code class="literal">
NULL
</code>
, the firewall
records allowlist rules for statements received from
any account that is a member of the group.
</p>
</li>
<li class="listitem">
<p>
If the value is non-
<code class="literal">
NULL
</code>
, the
firewall records allowlist rules only for statements
received from the named account (which should be a
member of the group).
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
The
<code class="literal">
<em class="replaceable">
<code>
default-database
</code>
</em>
.firewall_group_allowlist
</code>
table lists allowlist rules of registered firewall group
profiles. The table has the following columns (with the
corresponding Performance Schema
<a class="link" href="performance-schema-firewall-group-allowlist-table.html" title="29.12.17.2 The firewall_group_allowlist Table">
<code class="literal">
firewall_group_allowlist
</code>
</a>
table
having similar but not necessarily identical columns):
</p>
<a class="indexterm" name="idm46045234051568">
</a>
<a class="indexterm" name="idm46045234050448">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
NAME
</code>
</p>
<p>
The group profile name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
RULE
</code>
</p>
<p>
A normalized statement indicating an acceptable statement
pattern for the profile. A profile allowlist is the union
of its rules.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ID
</code>
</p>
<p>
An integer column that is a primary key for the table.
</p>
</li>
</ul>
</div>
<p>
The
<code class="literal">
<em class="replaceable">
<code>
default-database
</code>
</em>
.firewall_membership
</code>
table lists the members (accounts) of registered firewall
group profiles. The table has the following columns (with the
corresponding Performance Schema
<a class="link" href="performance-schema-firewall-membership-table.html" title="29.12.17.3 The firewall_membership Table">
<code class="literal">
firewall_membership
</code>
</a>
table having
similar but not necessarily identical columns):
</p>
<a class="indexterm" name="idm46045234039536">
</a>
<a class="indexterm" name="idm46045234038496">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
GROUP_ID
</code>
</p>
<p>
The group profile name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
MEMBER_ID
</code>
</p>
<p>
The name of an account that is a member of the profile.
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-tables-account">
</a>
Firewall Account Profile Tables
</h6>
<p>
MySQL Enterprise Firewall maintains account profile information using tables in
the firewall database for persistent storage and
<code class="literal">
INFORMATION_SCHEMA
</code>
tables to provide views
into in-memory cached data. The firewall database can be the
<code class="literal">
mysql
</code>
system database or a custom schema
(see
<a class="xref" href="firewall-installation.html#firewall-install" title="Installing MySQL Enterprise Firewall">
Installing MySQL Enterprise Firewall
</a>
).
</p>
<p>
Each default database table is accessible only by accounts
that have the
<a class="link" href="privileges-provided.html#priv_select">
<code class="literal">
SELECT
</code>
</a>
privilege
for it. The
<code class="literal">
INFORMATION_SCHEMA
</code>
tables are
accessible by anyone.
</p>
<p>
These tables are deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
<p>
The
<code class="literal">
<em class="replaceable">
<code>
default-database
</code>
</em>
.firewall_users
</code>
table lists names and operational modes of registered firewall
account profiles. The table has the following columns (with
the corresponding
<a class="link" href="information-schema-mysql-firewall-users-table.html" title="28.7.2 The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table">
<code class="literal">
MYSQL_FIREWALL_USERS
</code>
</a>
table having
similar but not necessarily identical columns):
</p>
<a class="indexterm" name="idm46045234022080">
</a>
<a class="indexterm" name="idm46045234021040">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
USERHOST
</code>
</p>
<p>
The account profile name. Each account name has the format
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
MODE
</code>
</p>
<p>
The current operational mode for the profile. Permitted
mode values are
<code class="literal">
OFF
</code>
,
<code class="literal">
DETECTING
</code>
,
<code class="literal">
PROTECTING
</code>
,
<code class="literal">
RECORDING
</code>
, and
<code class="literal">
RESET
</code>
. For details about their
meanings, see
<a class="xref" href="firewall-usage.html#firewall-concepts" title="Firewall Concepts">
Firewall Concepts
</a>
.
</p>
</li>
</ul>
</div>
<p>
The
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_whitelist
</code>
table lists allowlist rules of registered firewall account
profiles. The table has the following columns (with the
corresponding
<a class="link" href="information-schema-mysql-firewall-whitelist-table.html" title="28.7.3 The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table">
<code class="literal">
MYSQL_FIREWALL_WHITELIST
</code>
</a>
table
having similar but not necessarily identical columns):
</p>
<a class="indexterm" name="idm46045234006544">
</a>
<a class="indexterm" name="idm46045234005504">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
USERHOST
</code>
</p>
<p>
The account profile name. Each account name has the format
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
RULE
</code>
</p>
<p>
A normalized statement indicating an acceptable statement
pattern for the profile. A profile allowlist is the union
of its rules.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ID
</code>
</p>
<p>
An integer column that is a primary key for the table.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="firewall-stored-routines">
</a>
MySQL Enterprise Firewall Stored Procedures
</h5>
</div>
</div>
</div>
<p>
MySQL Enterprise Firewall stored procedures perform tasks such as registering
profiles with the firewall, establishing their operational
mode, and managing transfer of firewall data between the cache
and persistent storage. These procedures invoke administrative
functions that provide an API for lower-level tasks.
</p>
<p>
Firewall stored procedures are created in the firewall
database. The firewall database can be the
<code class="literal">
mysql
</code>
system database or a custom schema
(see
<a class="xref" href="firewall-installation.html#firewall-install" title="Installing MySQL Enterprise Firewall">
Installing MySQL Enterprise Firewall
</a>
).
</p>
<p>
To invoke a firewall stored procedure, either do so while the
specified firewall database is the default database, or
qualify the procedure name with the database name. For
example, if
<code class="literal">
mysql
</code>
is the firewall database:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa32225470"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_set_firewall_group_mode<span class="token punctuation">(</span><span class="token keyword"><em class="replaceable">group</em></span><span class="token punctuation">,</span> <span class="token keyword"><em class="replaceable">mode</em></span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
In MySQL 8.4, firewall stored procedures are
transactional; if an error occurs during execution of a
firewall stored procedure, all changes made by it up to that
point are rolled back, and an error is reported.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
If you have installed MySQL Enterprise Firewall in a custom schema, then make
appropriate substitution for your system. For example, if
the firewall is installed in the
<code class="literal">
fwdb
</code>
schema, then execute the stored procedures like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa72957546"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> fwdb<span class="token punctuation">.</span>sp_set_firewall_group_mode<span class="token punctuation">(</span><span class="token keyword"><em class="replaceable">group</em></span><span class="token punctuation">,</span> <span class="token keyword"><em class="replaceable">mode</em></span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
</p>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-stored-routines-group" title="Firewall Group Profile Stored Procedures">
Firewall Group Profile Stored Procedures
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-stored-routines-account" title="Firewall Account Profile Stored Procedures">
Firewall Account Profile Stored Procedures
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-stored-routines-miscellaneous" title="Firewall Miscellaneous Stored Procedures">
Firewall Miscellaneous Stored Procedures
</a>
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-stored-routines-group">
</a>
Firewall Group Profile Stored Procedures
</h6>
<p>
These stored procedures perform management operations on
firewall group profiles:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
sp_firewall_group_delist(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233977712">
</a>
<a class="indexterm" name="idm46045233976592">
</a>
<p>
This stored procedure removes an account from a firewall
group profile.
</p>
<p>
If the call succeeds, the change in group membership is
made to both the in-memory cache and persistent storage.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the
affected group profile.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The account to
remove, as a string in
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
format.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa10033178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_firewall_group_delist<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<code class="literal">
sp_firewall_group_enlist(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233965568">
</a>
<a class="indexterm" name="idm46045233964448">
</a>
<p>
This stored procedure adds an account to a firewall group
profile. It is not necessary to register the account
itself with the firewall before adding the account to the
group.
</p>
<p>
If the call succeeds, the change in group membership is
made to both the in-memory cache and persistent storage.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the
affected group profile.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The account to add,
as a string in
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
format.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa33087814"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_firewall_group_enlist<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<code class="literal">
sp_reload_firewall_group_rules(
<em class="replaceable">
<code>
group
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233953744">
</a>
<a class="indexterm" name="idm46045233952608">
</a>
<p>
This stored procedure provides control over firewall
operation for individual group profiles. The procedure
uses firewall administrative functions to reload the
in-memory rules for a group profile from the rules stored
in the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_group_allowlist
</code>
table.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the
affected group profile.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa18323832"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_reload_firewall_group_rules<span class="token punctuation">(</span><span class="token string">'myapp'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
This procedure clears the group profile in-memory
allowlist rules before reloading them from persistent
storage, and sets the profile mode to
<code class="literal">
OFF
</code>
. If the profile mode was not
<code class="literal">
OFF
</code>
prior to the
<code class="literal">
sp_reload_firewall_group_rules()
</code>
call, use
<code class="literal">
sp_set_firewall_group_mode()
</code>
to
restore its previous mode after reloading the rules. For
example, if the profile was in
<code class="literal">
PROTECTING
</code>
mode, that is no longer
true after calling
<code class="literal">
sp_reload_firewall_group_rules()
</code>
and
you must set it to
<code class="literal">
PROTECTING
</code>
again
explicitly.
</p>
</div>
</li>
<li class="listitem">
<p>
<code class="literal">
sp_set_firewall_group_mode(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233937152">
</a>
<a class="indexterm" name="idm46045233936032">
</a>
<p>
This stored procedure establishes the operational mode for
a firewall group profile, after registering the profile
with the firewall if it was not already registered. The
procedure also invokes firewall administrative functions
as necessary to transfer firewall data between the cache
and persistent storage. This procedure may be called even
if the
<code class="literal">
mysql_firewall_mode
</code>
system
variable is
<code class="literal">
OFF
</code>
, although setting the
mode for a profile has no operational effect until the
firewall is enabled.
</p>
<p>
If the profile previously existed, any recording
limitation for it remains unchanged. To set or clear the
limitation, call
<code class="literal">
sp_set_firewall_group_mode_and_user()
</code>
instead.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the
affected group profile.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
mode
</code>
</em>
: The operational mode
for the profile, as a string. Permitted mode values
are
<code class="literal">
OFF
</code>
,
<code class="literal">
DETECTING
</code>
,
<code class="literal">
PROTECTING
</code>
, and
<code class="literal">
RECORDING
</code>
. For details about their
meanings, see
<a class="xref" href="firewall-usage.html#firewall-concepts" title="Firewall Concepts">
Firewall Concepts
</a>
.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa99067349"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_set_firewall_group_mode<span class="token punctuation">(</span><span class="token string">'myapp'</span><span class="token punctuation">,</span> <span class="token string">'PROTECTING'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<code class="literal">
sp_set_firewall_group_mode_and_user(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233919584">
</a>
<a class="indexterm" name="idm46045233918448">
</a>
<p>
This stored procedure registers a group with the firewall
and establishes its operational mode, similar to
<code class="literal">
sp_set_firewall_group_mode()
</code>
, but also
specifies the training account to be used when the group
is in
<code class="literal">
RECORDING
</code>
mode.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the
affected group profile.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
mode
</code>
</em>
: The operational mode
for the profile, as a string. Permitted mode values
are
<code class="literal">
OFF
</code>
,
<code class="literal">
DETECTING
</code>
,
<code class="literal">
PROTECTING
</code>
, and
<code class="literal">
RECORDING
</code>
. For details about their
meanings, see
<a class="xref" href="firewall-usage.html#firewall-concepts" title="Firewall Concepts">
Firewall Concepts
</a>
.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The training account
for the group profile, to be used when the profile is
in
<code class="literal">
RECORDING
</code>
mode. The value is
<code class="literal">
NULL
</code>
, or a
non-
<code class="literal">
NULL
</code>
account that has the
format
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: square; ">
<li class="listitem">
<p>
If the value is
<code class="literal">
NULL
</code>
, the
firewall records allowlist rules for statements
received from any account that is a member of the
group.
</p>
</li>
<li class="listitem">
<p>
If the value is non-
<code class="literal">
NULL
</code>
, the
firewall records allowlist rules only for
statements received from the named account (which
should be a member of the group).
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54995887"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> mysql<span class="token punctuation">.</span>sp_set_firewall_group_mode_and_user<span class="token punctuation">(</span><span class="token string">'myapp'</span><span class="token punctuation">,</span> <span class="token string">'RECORDING'</span><span class="token punctuation">,</span> <span class="token string">'myapp_user1@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
<h6>
<a name="firewall-stored-routines-account">
</a>
Firewall Account Profile Stored Procedures
</h6>
<p>
These stored procedures perform management operations on
firewall account profiles:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
sp_reload_firewall_rules(
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233893728">
</a>
<a class="indexterm" name="idm46045233892608">
</a>
<p>
This stored procedure provides control over firewall
operation for individual account profiles. The procedure
uses firewall administrative functions to reload the
in-memory rules for an account profile from the rules
stored in the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_whitelist
</code>
table.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The name of the
affected account profile, as a string in
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
format.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa66121744"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sp_reload_firewall_rules<span class="token punctuation">(</span><span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
This procedure clears the account profile in-memory
allowlist rules before reloading them from persistent
storage, and sets the profile mode to
<code class="literal">
OFF
</code>
. If the profile mode was not
<code class="literal">
OFF
</code>
prior to the
<code class="literal">
sp_reload_firewall_rules()
</code>
call, use
<code class="literal">
sp_set_firewall_mode()
</code>
to restore its
previous mode after reloading the rules. For example, if
the profile was in
<code class="literal">
PROTECTING
</code>
mode,
that is no longer true after calling
<code class="literal">
sp_reload_firewall_rules()
</code>
and you
must set it to
<code class="literal">
PROTECTING
</code>
again
explicitly.
</p>
</div>
<p>
This procedure is deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
sp_set_firewall_mode(
<em class="replaceable">
<code>
user
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233874624">
</a>
<a class="indexterm" name="idm46045233873504">
</a>
<p>
This stored procedure establishes the operational mode for
a firewall account profile, after registering the profile
with the firewall if it was not already registered. The
procedure also invokes firewall administrative functions
as necessary to transfer firewall data between the cache
and persistent storage. This procedure may be called even
if the
<code class="literal">
mysql_firewall_mode
</code>
system
variable is
<code class="literal">
OFF
</code>
, although setting the
mode for a profile has no operational effect until the
firewall is enabled.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The name of the
affected account profile, as a string in
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
format.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
mode
</code>
</em>
: The operational mode
for the profile, as a string. Permitted mode values
are
<code class="literal">
OFF
</code>
,
<code class="literal">
DETECTING
</code>
,
<code class="literal">
PROTECTING
</code>
,
<code class="literal">
RECORDING
</code>
, and
<code class="literal">
RESET
</code>
. For details about their
meanings, see
<a class="xref" href="firewall-usage.html#firewall-concepts" title="Firewall Concepts">
Firewall Concepts
</a>
.
</p>
</li>
</ul>
</div>
<p>
Switching an account profile to any mode but
<code class="literal">
RECORDING
</code>
synchronizes its firewall
cache data to the firewall database tables that provide
persistent underlying storage (
<code class="literal">
mysql
</code>
or
custom). Switching the mode from
<code class="literal">
OFF
</code>
to
<code class="literal">
RECORDING
</code>
reloads the allowlist from
the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_whitelist
</code>
table into the cache.
</p>
<p>
If an account profile has an empty allowlist, its mode
cannot be set to
<code class="literal">
PROTECTING
</code>
because the
profile would reject every statement, effectively
prohibiting the account from executing statements. In
response to such a mode-setting attempt, the firewall
produces a diagnostic message that is returned as a result
set rather than as an SQL error:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4621723"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sp_set_firewall_mode<span class="token punctuation">(</span><span class="token string">'a@b'</span><span class="token punctuation">,</span><span class="token string">'PROTECTING'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> set_firewall_mode(arg_userhost, arg_mode) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ERROR: PROTECTING mode requested for a@b but the allowlist is empty. <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This procedure is deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-stored-routines-miscellaneous">
</a>
Firewall Miscellaneous Stored Procedures
</h6>
<p>
These stored procedures perform miscellaneous firewall
management operations.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
sp_migrate_firewall_user_to_group(
<em class="replaceable">
<code>
user
</code>
</em>
,
<em class="replaceable">
<code>
group
</code>
</em>
)
</code>
</p>
<a class="indexterm" name="idm46045233846832">
</a>
<a class="indexterm" name="idm46045233845696">
</a>
<p>
The
<code class="literal">
sp_migrate_firewall_user_to_group()
</code>
stored procedure converts a firewall account profile to a
group profile with the account as its single enlisted
member. Run the
<code class="filename">
firewall_profile_migration.sql
</code>
script
to install it. The conversion procedure is discussed in
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
<p>
This routine requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
Arguments:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<em class="replaceable">
<code>
user
</code>
</em>
: The name of the
account profile to convert to a group profile, as a
string in
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
format. The account profile must exist, and must not
currently be in
<code class="literal">
RECORDING
</code>
mode.
</p>
</li>
<li class="listitem">
<p>
<em class="replaceable">
<code>
group
</code>
</em>
: The name of the new
group profile, which must not already exist. The new
group profile has the named account as its single
enlisted member, and that member is set as the group
training account. The group profile operational mode
is taken from the account profile operational mode.
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa93791596"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sp_migrate_firewall_user_to_group<span class="token punctuation">(</span><span class="token string">'fwuser@localhost'</span><span class="token punctuation">,</span> 'mygroup<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="firewall-functions">
</a>
MySQL Enterprise Firewall Administrative Functions
</h5>
</div>
</div>
</div>
<p>
MySQL Enterprise Firewall administrative functions provide an API for lower-level
tasks such as synchronizing the firewall cache with the
underlying system tables.
</p>
<p>
<span class="emphasis">
<em>
Under normal operation, these functions are invoked
by the firewall stored procedures, not directly by
users.
</em>
</span>
For that reason, these function descriptions
do not include details such as information about their
arguments and return types.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-functions-group" title="Firewall Group Profile Functions">
Firewall Group Profile Functions
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-functions-account" title="Firewall Account Profile Functions">
Firewall Account Profile Functions
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="firewall-reference.html#firewall-functions-miscellaneous" title="Firewall Miscellaneous Functions">
Firewall Miscellaneous Functions
</a>
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-functions-group">
</a>
Firewall Group Profile Functions
</h6>
<p>
These functions perform management operations on firewall
group profiles:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="function_firewall-group-delist">
</a>
<a class="link" href="firewall-reference.html#function_firewall-group-delist">
<code class="literal">
firewall_group_delist(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233820368">
</a>
<a class="indexterm" name="idm46045233819248">
</a>
<p>
This function removes an account from a group profile. It
requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa84127619"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> firewall_group_delist<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="function_firewall-group-enlist">
</a>
<a class="link" href="firewall-reference.html#function_firewall-group-enlist">
<code class="literal">
firewall_group_enlist(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233811168">
</a>
<a class="indexterm" name="idm46045233810048">
</a>
<p>
This function adds an account to a group profile. It
requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
It is not necessary to register the account itself with
the firewall before adding the account to the group.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa48490624"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> firewall_group_enlist<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="function_read-firewall-group-allowlist">
</a>
<a class="link" href="firewall-reference.html#function_read-firewall-group-allowlist">
<code class="literal">
read_firewall_group_allowlist(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
rule
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233801392">
</a>
<a class="indexterm" name="idm46045233800272">
</a>
<p>
This aggregate function updates the recorded-statement
cache for the named group profile through a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement on the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_group_allowlist
</code>
table. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa74562396"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> read_firewall_group_allowlist<span class="token punctuation">(</span><span class="token string">'my_fw_group'</span><span class="token punctuation">,</span> fgw<span class="token punctuation">.</span>rule<span class="token punctuation">)</span>
<span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>firewall_group_allowlist <span class="token keyword">AS</span> fgw
<span class="token keyword">WHERE</span> <span class="token keyword">NAME</span> <span class="token operator">=</span> <span class="token string">'my_fw_group'</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="function_read-firewall-groups">
</a>
<a class="link" href="firewall-reference.html#function_read-firewall-groups">
<code class="literal">
read_firewall_groups(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
,
<em class="replaceable">
<code>
user
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233789184">
</a>
<a class="indexterm" name="idm46045233788064">
</a>
<p>
This aggregate function updates the firewall group profile
cache through a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement on the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_groups
</code>
table. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39162298"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> read_firewall_groups<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'RECORDING'</span><span class="token punctuation">,</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">)</span>
<span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>firewall_groups<span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="function_set-firewall-group-mode">
</a>
<a class="link" href="firewall-reference.html#function_set-firewall-group-mode">
<code class="literal">
set_firewall_group_mode(
<em class="replaceable">
<code>
group
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
[,
<em class="replaceable">
<code>
user
</code>
</em>
])
</code>
</a>
</p>
<a class="indexterm" name="idm46045233777136">
</a>
<a class="indexterm" name="idm46045233776016">
</a>
<p>
This function manages the group profile cache, establishes
the profile operational mode, and optionally specifies the
profile training account. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege.
</p>
<p>
If the optional
<em class="replaceable">
<code>
user
</code>
</em>
argument
is not given, any previous
<em class="replaceable">
<code>
user
</code>
</em>
setting for the profile remains unchanged. To change the
setting, call the function with a third argument.
</p>
<p>
If the optional
<em class="replaceable">
<code>
user
</code>
</em>
argument
is given, it specifies the training account for the group
profile, to be used when the profile is in
<code class="literal">
RECORDING
</code>
mode. The value is
<code class="literal">
NULL
</code>
, or a non-
<code class="literal">
NULL
</code>
account that has the format
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
If the value is
<code class="literal">
NULL
</code>
, the firewall
records allowlist rules for statements received from
any account that is a member of the group.
</p>
</li>
<li class="listitem">
<p>
If the value is non-
<code class="literal">
NULL
</code>
, the
firewall records allowlist rules only for statements
received from the named account (which should be a
member of the group).
</p>
</li>
</ul>
</div>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa63474900"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> set_firewall_group_mode<span class="token punctuation">(</span><span class="token string">'g'</span><span class="token punctuation">,</span> <span class="token string">'DETECTING'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
<h6>
<a name="firewall-functions-account">
</a>
Firewall Account Profile Functions
</h6>
<p>
These functions perform management operations on firewall
account profiles:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="function_read-firewall-users">
</a>
<a class="link" href="firewall-reference.html#function_read-firewall-users">
<code class="literal">
read_firewall_users(
<em class="replaceable">
<code>
user
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233755872">
</a>
<a class="indexterm" name="idm46045233754752">
</a>
<p>
This aggregate function updates the firewall account
profile cache through a
<code class="literal">
SELECT
</code>
statement on the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_users
</code>
table. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33981938"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> read_firewall_users<span class="token punctuation">(</span><span class="token string">'fwuser@localhost'</span><span class="token punctuation">,</span> <span class="token string">'RECORDING'</span><span class="token punctuation">)</span>
<span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>firewall_users<span class="token punctuation">;</span></code></pre>
</div>
<p>
This function is deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="function_read-firewall-whitelist">
</a>
<a class="link" href="firewall-reference.html#function_read-firewall-whitelist">
<code class="literal">
read_firewall_whitelist(
<em class="replaceable">
<code>
user
</code>
</em>
,
<em class="replaceable">
<code>
rule
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233742304">
</a>
<a class="indexterm" name="idm46045233741184">
</a>
<p>
This aggregate function updates the recorded-statement
cache for the named account profile through a
<code class="literal">
SELECT
</code>
statement on the
<code class="literal">
<em class="replaceable">
<code>
firewall-database
</code>
</em>
.firewall_whitelist
</code>
table. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25569961"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> read_firewall_whitelist<span class="token punctuation">(</span><span class="token string">'fwuser@localhost'</span><span class="token punctuation">,</span> fw<span class="token punctuation">.</span>rule<span class="token punctuation">)</span>
<span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>firewall_whitelist <span class="token keyword">AS</span> fw
<span class="token keyword">WHERE</span> USERHOST <span class="token operator">=</span> <span class="token string">'fwuser@localhost'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This function is deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="function_set-firewall-mode">
</a>
<a class="link" href="firewall-reference.html#function_set-firewall-mode">
<code class="literal">
set_firewall_mode(
<em class="replaceable">
<code>
user
</code>
</em>
,
<em class="replaceable">
<code>
mode
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233728576">
</a>
<a class="indexterm" name="idm46045233727472">
</a>
<p>
This function manages the account profile cache and
establishes the profile operational mode. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa95653569"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> set_firewall_mode<span class="token punctuation">(</span><span class="token string">'fwuser@localhost'</span><span class="token punctuation">,</span> <span class="token string">'RECORDING'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This function is deprecated, and subject to removal in a
future MySQL version. See
<a class="xref" href="firewall-usage.html#firewall-account-profile-migration" title="Migrating Account Profiles to Group Profiles">
Migrating Account Profiles to Group Profiles
</a>
.
</p>
</li>
</ul>
</div>
<h6>
<a name="firewall-functions-miscellaneous">
</a>
Firewall Miscellaneous Functions
</h6>
<p>
These functions perform miscellaneous firewall operations:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="function_mysql-firewall-flush-status">
</a>
<a class="link" href="firewall-reference.html#function_mysql-firewall-flush-status">
<code class="literal">
mysql_firewall_flush_status()
</code>
</a>
</p>
<a class="indexterm" name="idm46045233715600">
</a>
<a class="indexterm" name="idm46045233714480">
</a>
<p>
This function resets several firewall status variables to
0:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_denied">
<code class="literal">
Firewall_access_denied
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_granted">
<code class="literal">
Firewall_access_granted
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_suspicious">
<code class="literal">
Firewall_access_suspicious
</code>
</a>
</p>
</li>
</ul>
</div>
<p>
This function requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa23411782"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> mysql_firewall_flush_status<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="function_normalize-statement">
</a>
<a class="link" href="firewall-reference.html#function_normalize-statement">
<code class="literal">
normalize_statement(
<em class="replaceable">
<code>
stmt
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045233698480">
</a>
<a class="indexterm" name="idm46045233697360">
</a>
<p>
This function normalizes an SQL statement into the digest
form used for allowlist rules. It requires the
<a class="link" href="privileges-provided.html#priv_firewall-admin">
<code class="literal">
FIREWALL_ADMIN
</code>
</a>
privilege or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege.
</p>
<p>
Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa18629669"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> normalize_statement<span class="token punctuation">(</span><span class="token string">'SELECT * FROM t1 WHERE c1 > 2'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The same digest functionality is available outside
firewall context using the
<a class="link" href="encryption-functions.html#function_statement-digest-text">
<code class="literal">
STATEMENT_DIGEST_TEXT()
</code>
</a>
SQL function.
</p>
</div>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="firewall-system-variables">
</a>
MySQL Enterprise Firewall System Variables
</h5>
</div>
</div>
</div>
<p>
MySQL Enterprise Firewall supports the following system variables. Use them to
configure firewall operation. These variables are unavailable
unless the firewall is installed (see
<a class="xref" href="firewall-installation.html" title="8.4.7.2 Installing or Uninstalling MySQL Enterprise Firewall">
Section 8.4.7.2, “Installing or Uninstalling MySQL Enterprise Firewall”
</a>
).
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="sysvar_mysql_firewall_database">
</a>
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_database">
<code class="literal">
mysql_firewall_database
</code>
</a>
</p>
<a class="indexterm" name="idm46045233683584">
</a>
<a class="indexterm" name="idm46045233682544">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for mysql_firewall_database">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--mysql-firewall-database[=value]
</code>
</td>
</tr>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_database">
mysql_firewall_database
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
No
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
mysql
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
Specifies the database from which MySQL Enterprise Firewall reads data.
Typically, the
<code class="literal">
MYSQL_FIREWALL
</code>
server-side plugin stores its internal data (tables,
stored procedures, and functions) in the
<code class="literal">
mysql
</code>
system database, but you can
create and use a custom schema instead (see
<a class="xref" href="firewall-installation.html#firewall-install" title="Installing MySQL Enterprise Firewall">
Installing MySQL Enterprise Firewall
</a>
). This variable permits
specifying an alternative database name at startup.
</p>
</li>
<li class="listitem">
<p>
<a name="sysvar_mysql_firewall_mode">
</a>
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_mode">
<code class="literal">
mysql_firewall_mode
</code>
</a>
</p>
<a class="indexterm" name="idm46045233655456">
</a>
<a class="indexterm" name="idm46045233654416">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for mysql_firewall_mode">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--mysql-firewall-mode[={OFF|ON}]
</code>
</td>
</tr>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_mode">
mysql_firewall_mode
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
Yes
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
ON
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
Whether MySQL Enterprise Firewall is enabled (the default) or disabled.
</p>
</li>
<li class="listitem">
<p>
<a name="sysvar_mysql_firewall_reload_interval_seconds">
</a>
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_reload_interval_seconds">
<code class="literal">
mysql_firewall_reload_interval_seconds
</code>
</a>
</p>
<a class="indexterm" name="idm46045233629680">
</a>
<a class="indexterm" name="idm46045233628592">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for mysql_firewall_reload_interval_seconds">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--mysql-firewall-reload-interval-seconds[=value]
</code>
</td>
</tr>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_reload_interval_seconds">
mysql_firewall_reload_interval_seconds
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
No
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Integer
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
0
</code>
</td>
</tr>
<tr>
<th>
Minimum Value
</th>
<td>
<code class="literal">
60 (unless 0: OFF)
</code>
</td>
</tr>
<tr>
<th>
Maximum Value
</th>
<td>
<code class="literal">
INT_MAX
</code>
</td>
</tr>
<tr>
<th>
Unit
</th>
<td>
seconds
</td>
</tr>
</tbody>
</table>
</div>
<p>
Specifies the interval (in seconds) that the server-side
plugin uses to reload its internal cache from firewall
tables. When
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_reload_interval_seconds">
<code class="literal">
mysql_firewall_reload_interval_seconds
</code>
</a>
has a value of zero (the default), no periodic reloading
of data from tables occurs at runtime. Values between
<code class="literal">
0
</code>
and
<code class="literal">
60
</code>
(1 to 59)
are not acknowledged by the plugin. Instead, these values
adjust to
<code class="literal">
60
</code>
automatically.
</p>
<p>
This variable requires that the
<code class="literal">
scheduler
</code>
component be enabled
(
<code class="literal">
ON
</code>
). For more information, see
<a class="xref" href="firewall-usage.html#firewall-schedule-reloads" title="Scheduling Firewall Cache Reloads">
Scheduling Firewall Cache Reloads
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="sysvar_mysql_firewall_trace">
</a>
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_trace">
<code class="literal">
mysql_firewall_trace
</code>
</a>
</p>
<a class="indexterm" name="idm46045233590704">
</a>
<a class="indexterm" name="idm46045233589664">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for mysql_firewall_trace">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--mysql-firewall-trace[={OFF|ON}]
</code>
</td>
</tr>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_trace">
mysql_firewall_trace
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
Yes
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
OFF
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
Whether the MySQL Enterprise Firewall trace is enabled or disabled (the
default). When
<a class="link" href="firewall-reference.html#sysvar_mysql_firewall_trace">
<code class="literal">
mysql_firewall_trace
</code>
</a>
is
enabled, for
<code class="literal">
PROTECTING
</code>
mode, the
firewall writes rejected statements to the error log.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="firewall-status-variables">
</a>
MySQL Enterprise Firewall Status Variables
</h5>
</div>
</div>
</div>
<p>
MySQL Enterprise Firewall supports the following status variables. Use them to
obtain information about firewall operational status. These
variables are unavailable unless the firewall is installed
(see
<a class="xref" href="firewall-installation.html" title="8.4.7.2 Installing or Uninstalling MySQL Enterprise Firewall">
Section 8.4.7.2, “Installing or Uninstalling MySQL Enterprise Firewall”
</a>
). Firewall status
variables are set to 0 whenever the
<code class="literal">
MYSQL_FIREWALL
</code>
plugin is installed or the
server is started. Many of them are reset to zero by the
<a class="link" href="firewall-reference.html#function_mysql-firewall-flush-status">
<code class="literal">
mysql_firewall_flush_status()
</code>
</a>
function (see
<a class="xref" href="firewall-reference.html#firewall-functions" title="MySQL Enterprise Firewall Administrative Functions">
MySQL Enterprise Firewall Administrative Functions
</a>
).
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="statvar_Firewall_access_denied">
</a>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_denied">
<code class="literal">
Firewall_access_denied
</code>
</a>
</p>
<a class="indexterm" name="idm46045233557136">
</a>
<a class="indexterm" name="idm46045233556096">
</a>
<p>
The number of statements rejected by MySQL Enterprise Firewall.
</p>
</li>
<li class="listitem">
<p>
<a name="statvar_Firewall_access_granted">
</a>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_granted">
<code class="literal">
Firewall_access_granted
</code>
</a>
</p>
<a class="indexterm" name="idm46045233551600">
</a>
<a class="indexterm" name="idm46045233550560">
</a>
<p>
The number of statements accepted by MySQL Enterprise Firewall.
</p>
</li>
<li class="listitem">
<p>
<a name="statvar_Firewall_access_suspicious">
</a>
<a class="link" href="firewall-reference.html#statvar_Firewall_access_suspicious">
<code class="literal">
Firewall_access_suspicious
</code>
</a>
</p>
<a class="indexterm" name="idm46045233546160">
</a>
<a class="indexterm" name="idm46045233545056">
</a>
<p>
The number of statements logged by MySQL Enterprise Firewall as suspicious
for users who are in
<code class="literal">
DETECTING
</code>
mode.
</p>
</li>
<li class="listitem">
<p>
<a name="statvar_Firewall_cached_entries">
</a>
<a class="link" href="firewall-reference.html#statvar_Firewall_cached_entries">
<code class="literal">
Firewall_cached_entries
</code>
</a>
</p>
<a class="indexterm" name="idm46045233539792">
</a>
<a class="indexterm" name="idm46045233538752">
</a>
<p>
The number of statements recorded by MySQL Enterprise Firewall, including
duplicates.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/group-replication-failure-detection.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="group-replication-failure-detection">
</a>
20.1.4.2 Failure Detection
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045134376320">
</a>
<a class="indexterm" name="idm46045134374832">
</a>
<p>
Group Replication’s failure detection mechanism is a
distributed service which is able to identify that a server in
the group is not communicating with the others, and is therefore
suspected of being out of service. If the group’s consensus is
that the suspicion is probably true, the group takes a
coordinated decision to expel the member. Expelling a member
that is not communicating is necessary because the group needs a
majority of its members to agree on a transaction or view
change. If a member is not participating in these decisions, the
group must remove it to increase the chance that the group
contains a majority of correctly working members, and can
therefore continue to process transactions.
</p>
<p>
In a replication group, each member has a point-to-point
communication channel to each other member, creating a fully
connected graph. These connections are managed by the group
communication engine (XCom, a Paxos variant) and use TCP/IP
sockets. One channel is used to send messages to the member and
the other channel is used to receive messages from the member.
If a member does not receive messages from another member for 5
seconds, it suspects that the member has failed, and lists the
status of that member as
<code class="literal">
UNREACHABLE
</code>
in its
own Performance Schema table
<a class="link" href="performance-schema-replication-group-members-table.html" title="29.12.11.16 The replication_group_members Table">
<code class="literal">
replication_group_members
</code>
</a>
. Usually,
two members will suspect each other of having failed because
they are each not communicating with the other. It is possible,
though less likely, that member A suspects member B of having
failed but member B does not suspect member A of having failed -
perhaps due to a routing or firewall issue. A member can also
create a suspicion of itself. A member that is isolated from the
rest of the group suspects that all the others have failed.
</p>
<p>
If a suspicion lasts for more than 10 seconds, the suspecting
member tries to propagate its view that the suspect member is
faulty to the other members of the group. A suspecting member
only does this if it is a notifier, as calculated from its
internal XCom node number. If a member is actually isolated from
the rest of the group, it might attempt to propagate its view,
but that will have no consequences as it cannot secure a quorum
of the other members to agree on it. A suspicion only has
consequences if a member is a notifier, and its suspicion lasts
long enough to be propagated to the other members of the group,
and the other members agree on it. In that case, the suspect
member is marked for expulsion from the group in a coordinated
decision, and is expelled after the waiting period set by the
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_member_expel_timeout">
<code class="literal">
group_replication_member_expel_timeout
</code>
</a>
system variable expires and the expelling mechanism detects and
implements the expulsion.
</p>
<p>
Where the network is unstable and members frequently lose and
regain connection to each other in different combinations, it is
theoretically possible for a group to end up marking all its
members for expulsion, after which the group would cease to
exist and have to be set up again. To counter this possibility,
the Group Replication Group Communication System (GCS) tracks
the group members that have been marked for expulsion, and
treats them as if they were in the group of suspected members
when deciding if there is a majority. This ensures at least one
member remains in the group and the group can continue to exist.
When an expelled member has actually been removed from the
group, GCS removes its record of having marked the member for
expulsion, so that the member can rejoin the group if it is able
to do so.
</p>
<p>
For information on the Group Replication system variables that
you can configure to specify the responses of working group
members to failure situations, and the actions taken by group
members that are suspected of having failed, see
<a class="xref" href="group-replication-responses-failure.html" title="20.7.7 Responses to Failure Detection and Network Partitioning">
Section 20.7.7, “Responses to Failure Detection and Network Partitioning”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/charset-charsets.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="charset-charsets">
</a>
12.10 Supported Character Sets and Collations
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="charset-unicode-sets.html">
12.10.1 Unicode Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-we-sets.html">
12.10.2 West European Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-ce-sets.html">
12.10.3 Central European Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-se-me-sets.html">
12.10.4 South European and Middle East Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-baltic-sets.html">
12.10.5 Baltic Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-cyrillic-sets.html">
12.10.6 Cyrillic Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-asian-sets.html">
12.10.7 Asian Character Sets
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="charset-binary-set.html">
12.10.8 The Binary Character Set
</a>
</span>
</dt>
</dl>
</div>
<p>
This section indicates which character sets MySQL supports. There
is one subsection for each group of related character sets. For
each character set, the permissible collations are listed.
</p>
<p>
To list the available character sets and their default collations,
use the
<a class="link" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement">
<code class="literal">
SHOW CHARACTER SET
</code>
</a>
statement or query the
<code class="literal">
INFORMATION_SCHEMA
</code>
<a class="link" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table">
<code class="literal">
CHARACTER_SETS
</code>
</a>
table. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa10655964"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CHARACTER</span> <span class="token keyword">SET</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Charset <span class="token punctuation">|</span> Description <span class="token punctuation">|</span> Default collation <span class="token punctuation">|</span> Maxlen <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> armscii8 <span class="token punctuation">|</span> ARMSCII<span class="token punctuation">-</span>8 Armenian <span class="token punctuation">|</span> armscii8_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> ascii <span class="token punctuation">|</span> US ASCII <span class="token punctuation">|</span> ascii_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> big5 <span class="token punctuation">|</span> Big5 Traditional Chinese <span class="token punctuation">|</span> big5_chinese_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> binary <span class="token punctuation">|</span> Binary pseudo charset <span class="token punctuation">|</span> binary <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp1250 <span class="token punctuation">|</span> Windows Central European <span class="token punctuation">|</span> cp1250_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp1251 <span class="token punctuation">|</span> Windows Cyrillic <span class="token punctuation">|</span> cp1251_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp1256 <span class="token punctuation">|</span> Windows Arabic <span class="token punctuation">|</span> cp1256_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp1257 <span class="token punctuation">|</span> Windows Baltic <span class="token punctuation">|</span> cp1257_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp850 <span class="token punctuation">|</span> DOS West European <span class="token punctuation">|</span> cp850_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp852 <span class="token punctuation">|</span> DOS Central European <span class="token punctuation">|</span> cp852_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp866 <span class="token punctuation">|</span> DOS Russian <span class="token punctuation">|</span> cp866_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> cp932 <span class="token punctuation">|</span> SJIS for Windows Japanese <span class="token punctuation">|</span> cp932_japanese_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> dec8 <span class="token punctuation">|</span> DEC West European <span class="token punctuation">|</span> dec8_swedish_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> eucjpms <span class="token punctuation">|</span> UJIS for Windows Japanese <span class="token punctuation">|</span> eucjpms_japanese_ci <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> euckr <span class="token punctuation">|</span> EUC<span class="token punctuation">-</span>KR Korean <span class="token punctuation">|</span> euckr_korean_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> gb18030 <span class="token punctuation">|</span> China National Standard GB18030 <span class="token punctuation">|</span> gb18030_chinese_ci <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> gb2312 <span class="token punctuation">|</span> GB2312 Simplified Chinese <span class="token punctuation">|</span> gb2312_chinese_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> gbk <span class="token punctuation">|</span> GBK Simplified Chinese <span class="token punctuation">|</span> gbk_chinese_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> geostd8 <span class="token punctuation">|</span> GEOSTD8 Georgian <span class="token punctuation">|</span> geostd8_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> greek <span class="token punctuation">|</span> ISO 8859<span class="token punctuation">-</span>7 Greek <span class="token punctuation">|</span> greek_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> hebrew <span class="token punctuation">|</span> ISO 8859<span class="token punctuation">-</span>8 Hebrew <span class="token punctuation">|</span> hebrew_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> hp8 <span class="token punctuation">|</span> HP West European <span class="token punctuation">|</span> hp8_english_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> keybcs2 <span class="token punctuation">|</span> DOS Kamenicky Czech<span class="token punctuation">-</span>Slovak <span class="token punctuation">|</span> keybcs2_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> koi8r <span class="token punctuation">|</span> KOI8<span class="token punctuation">-</span>R Relcom Russian <span class="token punctuation">|</span> koi8r_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> koi8u <span class="token punctuation">|</span> KOI8<span class="token punctuation">-</span>U Ukrainian <span class="token punctuation">|</span> koi8u_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> latin1 <span class="token punctuation">|</span> cp1252 West European <span class="token punctuation">|</span> latin1_swedish_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> latin2 <span class="token punctuation">|</span> ISO 8859<span class="token punctuation">-</span>2 Central European <span class="token punctuation">|</span> latin2_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> latin5 <span class="token punctuation">|</span> ISO 8859<span class="token punctuation">-</span>9 Turkish <span class="token punctuation">|</span> latin5_turkish_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> latin7 <span class="token punctuation">|</span> ISO 8859<span class="token punctuation">-</span>13 Baltic <span class="token punctuation">|</span> latin7_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> macce <span class="token punctuation">|</span> Mac Central European <span class="token punctuation">|</span> macce_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> macroman <span class="token punctuation">|</span> Mac West European <span class="token punctuation">|</span> macroman_general_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> sjis <span class="token punctuation">|</span> Shift<span class="token punctuation">-</span>JIS Japanese <span class="token punctuation">|</span> sjis_japanese_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> swe7 <span class="token punctuation">|</span> 7bit Swedish <span class="token punctuation">|</span> swe7_swedish_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> tis620 <span class="token punctuation">|</span> TIS620 Thai <span class="token punctuation">|</span> tis620_thai_ci <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> ucs2 <span class="token punctuation">|</span> UCS<span class="token punctuation">-</span>2 Unicode <span class="token punctuation">|</span> ucs2_general_ci <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> ujis <span class="token punctuation">|</span> EUC<span class="token punctuation">-</span>JP Japanese <span class="token punctuation">|</span> ujis_japanese_ci <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> utf16 <span class="token punctuation">|</span> UTF<span class="token punctuation">-</span>16 Unicode <span class="token punctuation">|</span> utf16_general_ci <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> utf16le <span class="token punctuation">|</span> UTF<span class="token punctuation">-</span>16LE Unicode <span class="token punctuation">|</span> utf16le_general_ci <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> utf32 <span class="token punctuation">|</span> UTF<span class="token punctuation">-</span>32 Unicode <span class="token punctuation">|</span> utf32_general_ci <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> utf8mb3 <span class="token punctuation">|</span> UTF<span class="token punctuation">-</span>8 Unicode <span class="token punctuation">|</span> utf8mb3_general_ci <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> utf8mb4 <span class="token punctuation">|</span> UTF<span class="token punctuation">-</span>8 Unicode <span class="token punctuation">|</span> utf8mb4_0900_ai_ci <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
In cases where a character set has multiple collations, it might
not be clear which collation is most suitable for a given
application. To avoid choosing the wrong collation, it can be
helpful to perform some comparisons with representative data
values to make sure that a given collation sorts values the way
you expect.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/x-plugin-option-variable-reference.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="x-plugin-option-variable-reference">
</a>
22.5.6.1 X Plugin Option and Variable Reference
</h4>
</div>
</div>
</div>
<p>
This table provides an overview of the command options, system
variables, and status variables provided by X Plugin.
</p>
<div class="table">
<a name="idm46045126514144">
</a>
<p class="title">
<b>
Table 22.2 X Plugin Option and Variable Reference
</b>
</p>
<div class="table-contents">
<table frame="box" rules="all" summary="Reference for X Plugin command-line options, system variables, and status variables.">
<colgroup>
<col style="width: 20%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
<col style="width: 15%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Name
</th>
<th scope="col">
Cmd-Line
</th>
<th scope="col">
Option File
</th>
<th scope="col">
System Var
</th>
<th scope="col">
Status Var
</th>
<th scope="col">
Var Scope
</th>
<th scope="col">
Dynamic
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#option_mysqld_mysqlx">
mysqlx
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_aborted_clients">
Mysqlx_aborted_clients
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_address">
Mysqlx_address
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_bind_address">
mysqlx_bind_address
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received">
Mysqlx_bytes_received
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_compressed_payload">
Mysqlx_bytes_received_compressed_payload
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_uncompressed_frame">
Mysqlx_bytes_received_uncompressed_frame
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent">
Mysqlx_bytes_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_compressed_payload">
Mysqlx_bytes_sent_compressed_payload
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_uncompressed_frame">
Mysqlx_bytes_sent_uncompressed_frame
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_algorithm">
Mysqlx_compression_algorithm
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Session
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_compression_algorithms">
mysqlx_compression_algorithms
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_level">
Mysqlx_compression_level
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Session
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_connect_timeout">
mysqlx_connect_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_accept_errors">
Mysqlx_connection_accept_errors
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_errors">
Mysqlx_connection_errors
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_accepted">
Mysqlx_connections_accepted
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_closed">
Mysqlx_connections_closed
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_rejected">
Mysqlx_connections_rejected
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_create_view">
Mysqlx_crud_create_view
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_delete">
Mysqlx_crud_delete
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_drop_view">
Mysqlx_crud_drop_view
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_find">
Mysqlx_crud_find
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_insert">
Mysqlx_crud_insert
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_modify_view">
Mysqlx_crud_modify_view
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_update">
Mysqlx_crud_update
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_default_compression_level">
mysqlx_deflate_default_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_max_client_compression_level">
mysqlx_deflate_max_client_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_document_id_unique_prefix">
mysqlx_document_id_unique_prefix
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_enable_hello_notice">
mysqlx_enable_hello_notice
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_sent">
Mysqlx_errors_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_unknown_message_type">
Mysqlx_errors_unknown_message_type
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_close">
Mysqlx_expect_close
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_open">
Mysqlx_expect_open
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_idle_worker_thread_timeout">
mysqlx_idle_worker_thread_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_init_error">
Mysqlx_init_error
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_interactive_timeout">
mysqlx_interactive_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_default_compression_level">
mysqlx_lz4_default_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_max_client_compression_level">
mysqlx_lz4_max_client_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_allowed_packet">
mysqlx_max_allowed_packet
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_connections">
mysqlx_max_connections
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_messages_sent">
Mysqlx_messages_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_min_worker_threads">
mysqlx_min_worker_threads
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_global_sent">
Mysqlx_notice_global_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_other_sent">
Mysqlx_notice_other_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_warning_sent">
Mysqlx_notice_warning_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notified_by_group_replication">
Mysqlx_notified_by_group_replication
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_port">
Mysqlx_port
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_port">
mysqlx_port
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_port_open_timeout">
mysqlx_port_open_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_read_timeout">
mysqlx_read_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Session
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_rows_sent">
Mysqlx_rows_sent
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions">
Mysqlx_sessions
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_accepted">
Mysqlx_sessions_accepted
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_closed">
Mysqlx_sessions_closed
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_fatal_error">
Mysqlx_sessions_fatal_error
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_killed">
Mysqlx_sessions_killed
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_rejected">
Mysqlx_sessions_rejected
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_socket">
Mysqlx_socket
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_socket">
mysqlx_socket
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accept_renegotiates">
Mysqlx_ssl_accept_renegotiates
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accepts">
Mysqlx_ssl_accepts
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_active">
Mysqlx_ssl_active
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_ca">
mysqlx_ssl_ca
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_capath">
mysqlx_ssl_capath
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_cert">
mysqlx_ssl_cert
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher">
Mysqlx_ssl_cipher
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_cipher">
mysqlx_ssl_cipher
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher_list">
Mysqlx_ssl_cipher_list
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_crl">
mysqlx_ssl_crl
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_crlpath">
mysqlx_ssl_crlpath
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_depth">
Mysqlx_ssl_ctx_verify_depth
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_mode">
Mysqlx_ssl_ctx_verify_mode
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_finished_accepts">
Mysqlx_ssl_finished_accepts
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_ssl_key">
mysqlx_ssl_key
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_after">
Mysqlx_ssl_server_not_after
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_before">
Mysqlx_ssl_server_not_before
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_depth">
Mysqlx_ssl_verify_depth
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_mode">
Mysqlx_ssl_verify_mode
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_version">
Mysqlx_ssl_version
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection">
Mysqlx_stmt_create_collection
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection_index">
Mysqlx_stmt_create_collection_index
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_disable_notices">
Mysqlx_stmt_disable_notices
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection">
Mysqlx_stmt_drop_collection
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection_index">
Mysqlx_stmt_drop_collection_index
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_enable_notices">
Mysqlx_stmt_enable_notices
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ensure_collection">
Mysqlx_stmt_ensure_collection
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_mysqlx">
Mysqlx_stmt_execute_mysqlx
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_sql">
Mysqlx_stmt_execute_sql
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_xplugin">
Mysqlx_stmt_execute_xplugin
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_get_collection_options">
Mysqlx_stmt_get_collection_options
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_kill_client">
Mysqlx_stmt_kill_client
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_clients">
Mysqlx_stmt_list_clients
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_notices">
Mysqlx_stmt_list_notices
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_objects">
Mysqlx_stmt_list_objects
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_modify_collection_options">
Mysqlx_stmt_modify_collection_options
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ping">
Mysqlx_stmt_ping
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Both
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_wait_timeout">
mysqlx_wait_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Session
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads">
Mysqlx_worker_threads
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads_active">
Mysqlx_worker_threads_active
</a>
</th>
<td>
</td>
<td>
</td>
<td>
</td>
<td>
Yes
</td>
<td>
Global
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_write_timeout">
mysqlx_write_timeout
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Session
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_default_compression_level">
mysqlx_zstd_default_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_max_client_compression_level">
mysqlx_zstd_max_client_compression_level
</a>
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
</td>
<td>
Global
</td>
<td>
Yes
</td>
</tr>
</tbody>
</table>
</div>
<div class="table-contents">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;">
<thead>
<tr>
<th scope="col" style="width: 332.25px;">
Name
</th>
<th scope="col" style="width: 60.1719px;">
Cmd-Line
</th>
<th scope="col" style="width: 69.5312px;">
Option File
</th>
<th scope="col" style="width: 71.4531px;">
System Var
</th>
<th scope="col" style="width: 66.6562px;">
Status Var
</th>
<th scope="col" style="width: 68.5938px;">
Var Scope
</th>
<th scope="col" style="width: 69.3438px;">
Dynamic
</th>
</tr>
</thead>
</table>
</div>
</div>
<br class="table-break"/>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-oci-marketplace-network-configuration.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="mysql-oci-marketplace-network-configuration">
</a>
34.3 Configuring Network Access
</h2>
</div>
</div>
</div>
<p>
For information on OCI Security Rules, see
<a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/Network/Concepts/securityrules.htm" target="_blank">
Security
Rules
</a>
.
</p>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
You must enable ingress on the following ports:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
22: SSH
</p>
</li>
<li class="listitem">
<p>
3306: MySQL
</p>
</li>
<li class="listitem">
<p>
33060: (optional) MySQL X Protocol. Used by MySQL Shell.
</p>
</li>
</ul>
</div>
<p>
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/group-replication-gtids.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="group-replication-gtids">
</a>
20.4.1 GTIDs and Group Replication
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045133721280">
</a>
<p>
Group Replication uses GTIDs (global transaction identifiers) to
track exactly which transactions have been committed on every
server instance. The settings
<a class="link" href="replication-options-gtids.html#sysvar_gtid_mode">
<code class="literal">
gtid_mode=ON
</code>
</a>
and
<a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency">
<code class="literal">
enforce_gtid_consistency=ON
</code>
</a>
are
required on all group members. Incoming transactions from clients
are assigned a GTID by the group member that receives them. Any
replicated transactions that are received by group members on
asynchronous replication channels from source servers outside the
group retain the GTIDs that they have when they arrive on the
group member.
</p>
<p>
The GTIDs that are assigned to incoming transactions from clients
use the group name specified by the
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_name">
<code class="literal">
group_replication_group_name
</code>
</a>
system variable as the UUID part of the identifier, rather than
the server UUID of the individual group member that received the
transaction. All the transactions received directly by the group
can therefore be identified and are grouped together in GTID sets,
and it does not matter which member originally received them. Each
group member has a block of consecutive GTIDs reserved for its
use, and when these are consumed it reserves more. The
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_gtid_assignment_block_size">
<code class="literal">
group_replication_gtid_assignment_block_size
</code>
</a>
system variable sets the size of the blocks, with a default of 1
million GTIDs in each block.
</p>
<p>
View change events (
<code class="literal">
View_change_log_event
</code>
),
which are generated by the group itself when a new member joins,
are given GTIDs when they are recorded in the binary log. By
default, the GTIDs for these events also use the group name
specified by the
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_name">
<code class="literal">
group_replication_group_name
</code>
</a>
system variable as the UUID part of the identifier. You can set
the Group Replication system variable
<a class="link" href="group-replication-system-variables.html#sysvar_group_replication_view_change_uuid">
<code class="literal">
group_replication_view_change_uuid
</code>
</a>
to use an alternative UUID in the GTIDs for view change events, so
that they are easy to distinguish from transactions received by
the group from clients. This can be useful if your setup allows
for failover between groups, and you need to identify and discard
transactions that were specific to the backup group. The
alternative UUID must be different from the server UUIDs of the
members. It must also be different from any UUIDs in the GTIDs
applied to anonymous transactions using the
<code class="literal">
ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS
</code>
option
of the
<code class="literal">
CHANGE REPLICATION SOURCE TO
</code>
statement.
</p>
<p>
<code class="literal">
GTID_ONLY=1
</code>
,
<code class="literal">
REQUIRE_ROW_FORMAT =
1
</code>
, and
<code class="literal">
SOURCE_AUTO_POSITION = 1
</code>
are
applied for the Group Replication channels
<code class="literal">
group_replication_applier
</code>
and
<code class="literal">
group_replication_recovery
</code>
. The settings are
made automatically on the Group Replication channels when they are
created, or when a member server in a replication group is
upgraded. These options are normally set using a
<a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement">
<code class="literal">
CHANGE REPLICATION SOURCE TO
</code>
</a>
statement, but note that you cannot disable them for a Group
Replication channel. With these options set, the group member does
not persist file names and file positions in the replication
metadata repositories for these channels. GTID auto-positioning
and GTID auto-skip are used to locate the correct receiver and
applier positions when necessary.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="group-replication-gtids-extra">
</a>
Extra Transactions
</h4>
</div>
</div>
</div>
<p>
If a joining member has transactions in its GTID set that are
not present on the existing members of the group, it is not
allowed to complete the distributed recovery process, and cannot
join the group. If a remote cloning operation was carried out,
these transactions would be deleted and lost, because the data
directory on the joining member is erased. If state transfer
from a donor's binary log was carried out, these transactions
could conflict with the group's transactions.
</p>
<p>
Extra transactions might be present on a member if an
administrative transaction is carried out on the instance while
Group Replication is stopped. To avoid introducing new
transactions in that way, always set the value of the
<a class="link" href="replication-options-binary-log.html#sysvar_sql_log_bin">
<code class="literal">
sql_log_bin
</code>
</a>
system variable to
<code class="literal">
OFF
</code>
before issuing administrative statements,
and back to
<code class="literal">
ON
</code>
afterwards:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63015034"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> SQL_LOG_BIN<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>
<span class="token operator"><</span>administrator <span class="token keyword">action</span><span class="token operator">></span>
<span class="token keyword">SET</span> SQL_LOG_BIN<span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Setting this system variable to
<code class="literal">
OFF
</code>
means
that the transactions that occur from that point until you set
it back to
<code class="literal">
ON
</code>
are not written to the binary
log and do not have GTIDs assigned to them.
</p>
<p>
If an extra transaction is present on a joining member, check
the binary log for the affected server to see what the extra
transaction actually contains. The safest method to reconcile
the joining member’s data and GTID set with the members
currently in the group is to use MySQL's cloning functionality
to transfer the content from a server in the group to the
affected server. For instructions to do this, see
<a class="xref" href="clone-plugin-remote.html" title="7.6.7.3 Cloning Remote Data">
Section 7.6.7.3, “Cloning Remote Data”
</a>
. If the
transaction is required, rerun it after the member has
successfully rejoined.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/load-xml.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="load-xml">
</a>
15.2.10 LOAD XML Statement
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045181441984">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa71343391"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">LOAD</span> <span class="token keyword">XML</span>
<span class="token punctuation">[</span><span class="token keyword">LOW_PRIORITY</span> <span class="token operator">|</span> <span class="token keyword">CONCURRENT</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">LOCAL</span><span class="token punctuation">]</span>
<span class="token keyword">INFILE</span> <span class="token string">'<em class="replaceable">file_name</em>'</span>
<span class="token punctuation">[</span><span class="token keyword">REPLACE</span> <span class="token operator">|</span> <span class="token keyword">IGNORE</span><span class="token punctuation">]</span>
<span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> <span class="token punctuation">[</span><em class="replaceable">db_name</em><span class="token punctuation">.</span><span class="token punctuation">]</span><em class="replaceable">tbl_name</em>
<span class="token punctuation">[</span><span class="token keyword">CHARACTER</span> <span class="token keyword">SET</span> <em class="replaceable">charset_name</em><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">ROWS</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<<em class="replaceable">tagname</em>>'</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">IGNORE</span> <span class="token keyword"><em class="replaceable">number</em></span> {<span class="token keyword">LINES</span> <span class="token operator">|</span> <span class="token keyword">ROWS</span>}<span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token punctuation">(</span><em class="replaceable">field_name_or_user_var</em>
<span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">field_name_or_user_var</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">SET</span> <em class="replaceable">col_name</em><span class="token operator">=</span>{<em class="replaceable">expr</em> <span class="token operator">|</span> <span class="token keyword">DEFAULT</span>}
<span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">col_name</em><span class="token operator">=</span>{<em class="replaceable">expr</em> <span class="token operator">|</span> <span class="token keyword">DEFAULT</span>}<span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span></code></pre>
</div>
<p>
The
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
statement reads data
from an XML file into a table. The
<em class="replaceable">
<code>
file_name
</code>
</em>
must be given as a literal
string. The
<em class="replaceable">
<code>
tagname
</code>
</em>
in the optional
<code class="literal">
ROWS IDENTIFIED BY
</code>
clause must also be given as
a literal string, and must be surrounded by angle brackets
(
<code class="literal">
<
</code>
and
<code class="literal">
>
</code>
).
</p>
<p>
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
acts as the complement of
running the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client in XML output mode
(that is, starting the client with the
<a class="link" href="mysql-command-options.html#option_mysql_xml">
<code class="option">
--xml
</code>
</a>
option). To write data from a
table to an XML file, you can invoke the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client with the
<a class="link" href="mysql-command-options.html#option_mysql_xml">
<code class="option">
--xml
</code>
</a>
and
<a class="link" href="mysql-command-options.html#option_mysql_execute">
<code class="option">
-e
</code>
</a>
options from
the system shell, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa34585956"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">--xml</span> <span class="token property">-e</span> <span class="token atrule">'SELECT * FROM mydb.mytable'</span> > file<span class="token punctuation">.</span>xml</code></pre>
</div>
<p>
To read the file back into a table, use
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD
XML
</code>
</a>
. By default, the
<code class="literal">
<row>
</code>
element is considered to be the equivalent of a database table
row; this can be changed using the
<code class="literal">
ROWS IDENTIFIED
BY
</code>
clause.
</p>
<p>
This statement supports three different XML formats:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Column names as attributes and column values as attribute
values:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-xml"><div class="docs-select-all right" id="sa49049230"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span><em class="replaceable">row</em></span> <span class="token attr-name"><em class="replaceable">column1</em></span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span><em class="replaceable">value1</em><span class="token punctuation">"</span></span> <span class="token attr-name"><em class="replaceable">column2</em></span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span><em class="replaceable">value2</em><span class="token punctuation">"</span></span> <span class="token attr-name">...</span><span class="token punctuation">/></span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Column names as tags and column values as the content of these
tags:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-xml"><div class="docs-select-all right" id="sa79424560"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span><em class="replaceable">row</em></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span><em class="replaceable">column1</em></span><span class="token punctuation">></span></span><em class="replaceable">value1</em><span class="token tag"><span class="token tag"><span class="token punctuation"></</span><em class="replaceable">column1</em></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span><em class="replaceable">column2</em></span><span class="token punctuation">></span></span><em class="replaceable">value2</em><span class="token tag"><span class="token tag"><span class="token punctuation"></</span><em class="replaceable">column2</em></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span><em class="replaceable">row</em></span><span class="token punctuation">></span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Column names are the
<code class="literal">
name
</code>
attributes of
<code class="literal">
<field>
</code>
tags, and values are the
contents of these tags:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-xml"><div class="docs-select-all right" id="sa84057789"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>row</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">'</span><em class="replaceable">column1</em><span class="token punctuation">'</span></span><span class="token punctuation">></span></span><em class="replaceable">value1</em><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">'</span><em class="replaceable">column2</em><span class="token punctuation">'</span></span><span class="token punctuation">></span></span><em class="replaceable">value2</em><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>row</span><span class="token punctuation">></span></span></code></pre>
</div>
<p>
This is the format used by other MySQL tools, such as
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
.
</p>
</li>
</ul>
</div>
<p>
All three formats can be used in the same XML file; the import
routine automatically detects the format for each row and
interprets it correctly. Tags are matched based on the tag or
attribute name and the column name.
</p>
<p>
The following clauses work essentially the same way for
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
as they do for
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
LOW_PRIORITY
</code>
or
<code class="literal">
CONCURRENT
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
LOCAL
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
REPLACE
</code>
or
<code class="literal">
IGNORE
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
CHARACTER SET
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
SET
</code>
</p>
</li>
</ul>
</div>
<p>
See
<a class="xref" href="load-data.html" title="15.2.9 LOAD DATA Statement">
Section 15.2.9, “LOAD DATA Statement”
</a>
, for more information about these
clauses.
</p>
<p>
<code class="literal">
(
<em class="replaceable">
<code>
field_name_or_user_var
</code>
</em>
,
...)
</code>
is a list of one or more comma-separated XML fields
or user variables. The name of a user variable used for this
purpose must match the name of a field from the XML file, prefixed
with
<code class="literal">
@
</code>
. You can use field names to select only
desired fields. User variables can be employed to store the
corresponding field values for subsequent re-use.
</p>
<p>
The
<code class="literal">
IGNORE
<em class="replaceable">
<code>
number
</code>
</em>
LINES
</code>
or
<code class="literal">
IGNORE
<em class="replaceable">
<code>
number
</code>
</em>
ROWS
</code>
clause causes the
first
<em class="replaceable">
<code>
number
</code>
</em>
rows in the XML file to be
skipped. It is analogous to the
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD
DATA
</code>
</a>
statement's
<code class="literal">
IGNORE ... LINES
</code>
clause.
</p>
<p>
Suppose that we have a table named
<code class="literal">
person
</code>
,
created as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa53385062"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">USE</span> test<span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> person <span class="token punctuation">(</span>
person_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
fname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
lname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
created <span class="token datatype">TIMESTAMP</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Suppose further that this table is initially empty.
</p>
<p>
Now suppose that we have a simple XML file
<code class="filename">
person.xml
</code>
, whose contents are as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-xml"><div class="docs-select-all right" id="sa67689216"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>list</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>1<span class="token punctuation">"</span></span> <span class="token attr-name">fname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Kapek<span class="token punctuation">"</span></span> <span class="token attr-name">lname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Sainnouine<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>2<span class="token punctuation">"</span></span> <span class="token attr-name">fname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Sajon<span class="token punctuation">"</span></span> <span class="token attr-name">lname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Rondela<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>3<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>fname</span><span class="token punctuation">></span></span>Likame<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>fname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>lname</span><span class="token punctuation">></span></span>Örrtmons<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>lname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>4<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>fname</span><span class="token punctuation">></span></span>Slar<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>fname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>lname</span><span class="token punctuation">></span></span>Manlanth<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>lname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>person_id<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>5<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>fname<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>Stoma<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>lname<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>Milu<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>person_id<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>6<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>fname<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>Nirtam<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>lname<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>Sklöd<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>7<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>fname</span><span class="token punctuation">></span></span>Sungam<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>fname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>lname</span><span class="token punctuation">></span></span>Dulbåd<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>lname</span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>8<span class="token punctuation">"</span></span> <span class="token attr-name">fname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Sraref<span class="token punctuation">"</span></span> <span class="token attr-name">lname</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Encmelt<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>list</span><span class="token punctuation">></span></span></code></pre>
</div>
<p>
Each of the permissible XML formats discussed previously is
represented in this example file.
</p>
<p>
To import the data in
<code class="filename">
person.xml
</code>
into the
<code class="literal">
person
</code>
table, you can use this statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86770523"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">LOCAL</span> <span class="token keyword">INFILE</span> <span class="token string">'person.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> person
<span class="token prompt"> -></span> <span class="token keyword">ROWS</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<person>'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 8 rows affected (0.00 sec)</span>
<span class="token output">Records: 8 Deleted: 0 Skipped: 0 Warnings: 0</span></code></pre>
</div>
<p>
Here, we assume that
<code class="filename">
person.xml
</code>
is located in
the MySQL data directory. If the file cannot be found, the
following error results:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa25318220"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR 2 (HY000): File '/person.xml' not found (Errcode: 2)</code></pre>
</div>
<p>
The
<code class="literal">
ROWS IDENTIFIED BY '<person>'
</code>
clause
means that each
<code class="literal">
<person>
</code>
element in the
XML file is considered equivalent to a row in the table into which
the data is to be imported. In this case, this is the
<code class="literal">
person
</code>
table in the
<code class="literal">
test
</code>
database.
</p>
<p>
As can be seen by the response from the server, 8 rows were
imported into the
<code class="literal">
test.person
</code>
table. This can
be verified by a simple
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa14653835"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> person_id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> created <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Kapek <span class="token punctuation">|</span> Sainnouine <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Sajon <span class="token punctuation">|</span> Rondela <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> Likame <span class="token punctuation">|</span> Örrtmons <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Slar <span class="token punctuation">|</span> Manlanth <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Stoma <span class="token punctuation">|</span> Nilu <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> Nirtam <span class="token punctuation">|</span> Sklöd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> Sungam <span class="token punctuation">|</span> Dulbåd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> Sreraf <span class="token punctuation">|</span> Encmelt <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">8 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
This shows, as stated earlier in this section, that any or all of
the 3 permitted XML formats may appear in a single file and be
read using
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
.
</p>
<p>
The inverse of the import operation just shown—that is,
dumping MySQL table data into an XML file—can be
accomplished using the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client from the
system shell, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa23174815"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">--xml</span> <span class="token property">-e</span> <span class="token atrule">"SELECT * FROM test.person"</span> > person-dump<span class="token punctuation">.</span>xml
<span class="token prompt">$> </span><span class="token command">cat</span> person-dump<span class="token punctuation">.</span>xml
<?xml version=<span class="token atrule">"1.0"</span>?>
<resultset statement=<span class="token atrule">"SELECT * FROM test.person"</span> xmlns<span class="token punctuation">:</span>xsi=<span class="token atrule">"http://www.w3.org/2001/XMLSchema-instance"</span>>
<row>
<field name=<span class="token atrule">"person_id"</span>>1</field>
<field name=<span class="token atrule">"fname"</span>>Kapek</field>
<field name=<span class="token atrule">"lname"</span>>Sainnouine</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>2</field>
<field name=<span class="token atrule">"fname"</span>>Sajon</field>
<field name=<span class="token atrule">"lname"</span>>Rondela</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>3</field>
<field name=<span class="token atrule">"fname"</span>>Likema</field>
<field name=<span class="token atrule">"lname"</span>>Örrtmons</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>4</field>
<field name=<span class="token atrule">"fname"</span>>Slar</field>
<field name=<span class="token atrule">"lname"</span>>Manlanth</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>5</field>
<field name=<span class="token atrule">"fname"</span>>Stoma</field>
<field name=<span class="token atrule">"lname"</span>>Nilu</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>6</field>
<field name=<span class="token atrule">"fname"</span>>Nirtam</field>
<field name=<span class="token atrule">"lname"</span>>Sklöd</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>7</field>
<field name=<span class="token atrule">"fname"</span>>Sungam</field>
<field name=<span class="token atrule">"lname"</span>>Dulbåd</field>
</row>
<row>
<field name=<span class="token atrule">"person_id"</span>>8</field>
<field name=<span class="token atrule">"fname"</span>>Sreraf</field>
<field name=<span class="token atrule">"lname"</span>>Encmelt</field>
</row>
</resultset></code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The
<a class="link" href="mysql-command-options.html#option_mysql_xml">
<code class="option">
--xml
</code>
</a>
option causes the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client to use XML formatting for its
output; the
<a class="link" href="mysql-command-options.html#option_mysql_execute">
<code class="option">
-e
</code>
</a>
option causes the client to execute the SQL statement
immediately following the option. See
<a class="xref" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
Section 6.5.1, “mysql — The MySQL Command-Line Client”
</a>
.
</p>
</div>
<p>
You can verify that the dump is valid by creating a copy of the
<code class="literal">
person
</code>
table and importing the dump file into
the new table, like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa424614"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">USE</span> test<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> person2 <span class="token operator">LIKE</span> person<span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">LOCAL</span> <span class="token keyword">INFILE</span> <span class="token string">'person-dump.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> person2<span class="token punctuation">;</span>
<span class="token output">Query OK, 8 rows affected (0.01 sec)</span>
<span class="token output">Records: 8 Deleted: 0 Skipped: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person2<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> person_id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> created <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Kapek <span class="token punctuation">|</span> Sainnouine <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Sajon <span class="token punctuation">|</span> Rondela <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> Likema <span class="token punctuation">|</span> Örrtmons <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Slar <span class="token punctuation">|</span> Manlanth <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Stoma <span class="token punctuation">|</span> Nilu <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> Nirtam <span class="token punctuation">|</span> Sklöd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> Sungam <span class="token punctuation">|</span> Dulbåd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> Sreraf <span class="token punctuation">|</span> Encmelt <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">8 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
There is no requirement that every field in the XML file be
matched with a column in the corresponding table. Fields which
have no corresponding columns are skipped. You can see this by
first emptying the
<code class="literal">
person2
</code>
table and dropping
the
<code class="literal">
created
</code>
column, then using the same
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
statement we just employed
previously, like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40410738"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">TRUNCATE</span> person2<span class="token punctuation">;</span>
<span class="token output">Query OK, 8 rows affected (0.26 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> person2 <span class="token keyword">DROP</span> <span class="token keyword">COLUMN</span> created<span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.52 sec)</span>
<span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> person2\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> person2
Create Table<span class="token punctuation">:</span> CREATE TABLE `person2` (
`person_id` int NOT NULL,
`fname` varchar(40) DEFAULT NULL,
`lname` varchar(40) DEFAULT NULL,
PRIMARY KEY (`person_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
</span><span class="token output">1 row in set (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">LOCAL</span> <span class="token keyword">INFILE</span> <span class="token string">'person-dump.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> person2<span class="token punctuation">;</span>
<span class="token output">Query OK, 8 rows affected (0.01 sec)</span>
<span class="token output">Records: 8 Deleted: 0 Skipped: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person2<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> person_id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Kapek <span class="token punctuation">|</span> Sainnouine <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Sajon <span class="token punctuation">|</span> Rondela <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> Likema <span class="token punctuation">|</span> Örrtmons <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Slar <span class="token punctuation">|</span> Manlanth <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Stoma <span class="token punctuation">|</span> Nilu <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> Nirtam <span class="token punctuation">|</span> Sklöd <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> Sungam <span class="token punctuation">|</span> Dulbåd <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> Sreraf <span class="token punctuation">|</span> Encmelt <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">8 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
The order in which the fields are given within each row of the XML
file does not affect the operation of
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD
XML
</code>
</a>
; the field order can vary from row to row, and is
not required to be in the same order as the corresponding columns
in the table.
</p>
<p>
As mentioned previously, you can use a
<code class="literal">
(
<em class="replaceable">
<code>
field_name_or_user_var
</code>
</em>
,
...)
</code>
list of one or more XML fields (to select desired
fields only) or user variables (to store the corresponding field
values for later use). User variables can be especially useful
when you want to insert data from an XML file into table columns
whose names do not match those of the XML fields. To see how this
works, we first create a table named
<code class="literal">
individual
</code>
whose structure matches that of the
<code class="literal">
person
</code>
table, but whose columns are named differently:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa90374703"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> individual <span class="token punctuation">(</span>
<span class="token prompt"> -></span> individual_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> name1 <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> name2 <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> made <span class="token datatype">TIMESTAMP</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.42 sec)</span></code></pre>
</div>
<p>
In this case, you cannot simply load the XML file directly into
the table, because the field and column names do not match:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35901223"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">INFILE</span> <span class="token string">'../bin/person-dump.xml'</span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> test<span class="token punctuation">.</span>individual<span class="token punctuation">;</span>
<span class="token output">ERROR 1263 (22004)<span class="token punctuation">:</span> Column set to default value; NULL supplied to NOT NULL column 'individual_id' at row 1</span></code></pre>
</div>
<p>
This happens because the MySQL server looks for field names
matching the column names of the target table. You can work around
this problem by selecting the field values into user variables,
then setting the target table's columns equal to the values
of those variables using
<code class="literal">
SET
</code>
. You can perform
both of these operations in a single statement, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa26590574"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">INFILE</span> <span class="token string">'../bin/person-dump.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> test<span class="token punctuation">.</span>individual <span class="token punctuation">(</span><span class="token variable">@person_id</span><span class="token punctuation">,</span> <span class="token variable">@fname</span><span class="token punctuation">,</span> <span class="token variable">@lname</span><span class="token punctuation">,</span> <span class="token variable">@created</span><span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">SET</span> individual_id<span class="token operator">=</span><span class="token variable">@person_id</span><span class="token punctuation">,</span> name1<span class="token operator">=</span><span class="token variable">@fname</span><span class="token punctuation">,</span> name2<span class="token operator">=</span><span class="token variable">@lname</span><span class="token punctuation">,</span> made<span class="token operator">=</span><span class="token variable">@created</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 8 rows affected (0.05 sec)</span>
<span class="token output">Records: 8 Deleted: 0 Skipped: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> individual<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> individual_id <span class="token punctuation">|</span> name1 <span class="token punctuation">|</span> name2 <span class="token punctuation">|</span> made <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Kapek <span class="token punctuation">|</span> Sainnouine <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Sajon <span class="token punctuation">|</span> Rondela <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> Likema <span class="token punctuation">|</span> Örrtmons <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Slar <span class="token punctuation">|</span> Manlanth <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Stoma <span class="token punctuation">|</span> Nilu <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> Nirtam <span class="token punctuation">|</span> Sklöd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> Sungam <span class="token punctuation">|</span> Dulbåd <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> Srraf <span class="token punctuation">|</span> Encmelt <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>13 16:18:47 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">8 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
The names of the user variables
<span class="emphasis">
<em>
must
</em>
</span>
match
those of the corresponding fields from the XML file, with the
addition of the required
<code class="literal">
@
</code>
prefix to indicate
that they are variables. The user variables need not be listed or
assigned in the same order as the corresponding fields.
</p>
<p>
Using a
<code class="literal">
ROWS IDENTIFIED BY
'<
<em class="replaceable">
<code>
tagname
</code>
</em>
>'
</code>
clause, it
is possible to import data from the same XML file into database
tables with different definitions. For this example, suppose that
you have a file named
<code class="filename">
address.xml
</code>
which
contains the following XML:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-xml"><div class="docs-select-all right" id="sa36190955"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token prolog"><?xml version="1.0"?></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>list</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>1<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>fname</span><span class="token punctuation">></span></span>Robert<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>fname</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>lname</span><span class="token punctuation">></span></span>Jones<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>lname</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>address</span> <span class="token attr-name">address_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>1<span class="token punctuation">"</span></span> <span class="token attr-name">street</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Mill Creek Road<span class="token punctuation">"</span></span> <span class="token attr-name">zip</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>45365<span class="token punctuation">"</span></span> <span class="token attr-name">city</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Sidney<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>address</span> <span class="token attr-name">address_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>2<span class="token punctuation">"</span></span> <span class="token attr-name">street</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Main Street<span class="token punctuation">"</span></span> <span class="token attr-name">zip</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>28681<span class="token punctuation">"</span></span> <span class="token attr-name">city</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Taylorsville<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>person</span> <span class="token attr-name">person_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>2<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>fname</span><span class="token punctuation">></span></span>Mary<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>fname</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>lname</span><span class="token punctuation">></span></span>Smith<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>lname</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>address</span> <span class="token attr-name">address_id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>3<span class="token punctuation">"</span></span> <span class="token attr-name">street</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>River Road<span class="token punctuation">"</span></span> <span class="token attr-name">zip</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>80239<span class="token punctuation">"</span></span> <span class="token attr-name">city</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>Denver<span class="token punctuation">"</span></span><span class="token punctuation">/></span></span>
<span class="token comment" spellcheck="true"><!-- <address address_id="4" street="North Street" zip="37920" city="Knoxville"/> --></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>person</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>list</span><span class="token punctuation">></span></span></code></pre>
</div>
<p>
You can again use the
<code class="literal">
test.person
</code>
table as
defined previously in this section, after clearing all the
existing records from the table and then showing its structure as
shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa38738650"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">mysql<span class="token operator"><</span> <span class="token keyword">TRUNCATE</span> person<span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.04 sec)</span>
mysql<span class="token operator"><</span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> person\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> person
Create Table<span class="token punctuation">:</span> CREATE TABLE `person` (
`person_id` int(11) NOT NULL,
`fname` varchar(40) DEFAULT NULL,
`lname` varchar(40) DEFAULT NULL,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`person_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
</span><span class="token output">1 row in set (0.00 sec)</span></code></pre>
</div>
<p>
Now create an
<code class="literal">
address
</code>
table in the
<code class="literal">
test
</code>
database using the following
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25858576"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> address <span class="token punctuation">(</span>
address_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
person_id <span class="token datatype">INT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
street <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
zip <span class="token datatype">INT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
city <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
created <span class="token datatype">TIMESTAMP</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
To import the data from the XML file into the
<code class="literal">
person
</code>
table, execute the following
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
statement, which specifies
that rows are to be specified by the
<code class="literal">
<person>
</code>
element, as shown here;
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa89207969"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">LOCAL</span> <span class="token keyword">INFILE</span> <span class="token string">'address.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> person
<span class="token prompt"> -></span> <span class="token keyword">ROWS</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<person>'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 2 rows affected (0.00 sec)</span>
<span class="token output">Records: 2 Deleted: 0 Skipped: 0 Warnings: 0</span></code></pre>
</div>
<p>
You can verify that the records were imported using a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12803835"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> person_id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> created <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Robert <span class="token punctuation">|</span> Jones <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>24 17:37:06 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Mary <span class="token punctuation">|</span> Smith <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>24 17:37:06 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">2 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
Since the
<code class="literal">
<address>
</code>
elements in the XML
file have no corresponding columns in the
<code class="literal">
person
</code>
table, they are skipped.
</p>
<p>
To import the data from the
<code class="literal">
<address>
</code>
elements into the
<code class="literal">
address
</code>
table, use the
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
statement shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47748309"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">XML</span> <span class="token keyword">LOCAL</span> <span class="token keyword">INFILE</span> <span class="token string">'address.xml'</span>
<span class="token prompt"> -></span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> address
<span class="token prompt"> -></span> <span class="token keyword">ROWS</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<address>'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 3 rows affected (0.00 sec)</span>
<span class="token output">Records: 3 Deleted: 0 Skipped: 0 Warnings: 0</span></code></pre>
</div>
<p>
You can see that the data was imported using a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement such as this one:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa75491937"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> address<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> address_id <span class="token punctuation">|</span> person_id <span class="token punctuation">|</span> street <span class="token punctuation">|</span> zip <span class="token punctuation">|</span> city <span class="token punctuation">|</span> created <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Mill Creek Road <span class="token punctuation">|</span> 45365 <span class="token punctuation">|</span> Sidney <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>24 17:37:37 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Main Street <span class="token punctuation">|</span> 28681 <span class="token punctuation">|</span> Taylorsville <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>24 17:37:37 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> River Road <span class="token punctuation">|</span> 80239 <span class="token punctuation">|</span> Denver <span class="token punctuation">|</span> 2007<span class="token punctuation">-</span>07<span class="token punctuation">-</span>24 17:37:37 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">3 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
The data from the
<code class="literal">
<address>
</code>
element that
is enclosed in XML comments is not imported. However, since there
is a
<code class="literal">
person_id
</code>
column in the
<code class="literal">
address
</code>
table, the value of the
<code class="literal">
person_id
</code>
attribute from the parent
<code class="literal">
<person>
</code>
element for each
<code class="literal">
<address>
</code>
<span class="emphasis">
<em>
is
</em>
</span>
imported into the
<code class="literal">
address
</code>
table.
</p>
<p>
<b>
Security Considerations.
</b>
As with the
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
statement,
the transfer of the XML file from the client host to the server
host is initiated by the MySQL server. In theory, a patched
server could be built that would tell the client program to
transfer a file of the server's choosing rather than the file
named by the client in the
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD
XML
</code>
</a>
statement. Such a server could access any file on
the client host to which the client user has read access.
</p>
<p>
In a Web environment, clients usually connect to MySQL from a Web
server. A user that can run any command against the MySQL server
can use
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
LOCAL
</code>
</a>
to read any files to which the Web server process
has read access. In this environment, the client with respect to
the MySQL server is actually the Web server, not the remote
program being run by the user who connects to the Web server.
</p>
<p>
You can disable loading of XML files from clients by starting the
server with
<a class="link" href="server-system-variables.html#sysvar_local_infile">
<code class="literal">
--local-infile=0
</code>
</a>
or
<a class="link" href="server-system-variables.html#sysvar_local_infile">
<code class="literal">
--local-infile=OFF
</code>
</a>
. This option
can also be used when starting the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client
to disable
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
for the
duration of the client session.
</p>
<p>
To prevent a client from loading XML files from the server, do not
grant the
<a class="link" href="privileges-provided.html#priv_file">
<code class="literal">
FILE
</code>
</a>
privilege to the
corresponding MySQL user account, or revoke this privilege if the
client user account already has it.
</p>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
Revoking the
<a class="link" href="privileges-provided.html#priv_file">
<code class="literal">
FILE
</code>
</a>
privilege (or
not granting it in the first place) keeps the user only from
executing the
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
statement
(as well as the
<a class="link" href="string-functions.html#function_load-file">
<code class="literal">
LOAD_FILE()
</code>
</a>
function; it does
<span class="emphasis">
<em>
not
</em>
</span>
prevent the user from
executing
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
LOCAL
</code>
</a>
. To disallow this statement, you must start the
server or the client with
<code class="option">
--local-infile=OFF
</code>
.
</p>
<p>
In other words, the
<a class="link" href="privileges-provided.html#priv_file">
<code class="literal">
FILE
</code>
</a>
privilege affects only whether the client can read files on the
server; it has no bearing on whether the client can read files
on the local file system.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="replication-options">
</a>
19.1.6 Replication and Binary Logging Options and Variables
</h3>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="replication-options-reference.html">
19.1.6.1 Replication and Binary Logging Option and Variable Reference
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-options-source.html">
19.1.6.2 Replication Source Options and Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-options-replica.html">
19.1.6.3 Replica Server Options and Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-options-binary-log.html">
19.1.6.4 Binary Logging Options and Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-options-gtids.html">
19.1.6.5 Global Transaction ID System Variables
</a>
</span>
</dt>
</dl>
</div>
<p>
The following sections contain information about
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
options and server variables that are used
in replication and for controlling the binary log. Options and
variables for use on sources and replicas are covered separately, as
are options and variables relating to binary logging and global
transaction identifiers (GTIDs). A set of quick-reference tables
providing basic information about these options and variables is
also included.
</p>
<p>
<a name="sysvar_server_id">
</a>
Of particular importance is the
<a class="link" href="replication-options.html#sysvar_server_id">
<code class="literal">
server_id
</code>
</a>
system variable.
</p>
<a class="indexterm" name="idm46045145086784">
</a>
<a class="indexterm" name="idm46045145085696">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for server_id">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--server-id=#
</code>
</td>
</tr>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="replication-options.html#sysvar_server_id">
server_id
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
Yes
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Integer
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
1
</code>
</td>
</tr>
<tr>
<th>
Minimum Value
</th>
<td>
<code class="literal">
0
</code>
</td>
</tr>
<tr>
<th>
Maximum Value
</th>
<td>
<code class="literal">
4294967295
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
This variable specifies the server ID.
<a class="link" href="replication-options.html#sysvar_server_id">
<code class="literal">
server_id
</code>
</a>
is set to 1 by default.
The server can be started with this default ID, but when binary
logging is enabled, an informational message is issued if you did
not set
<a class="link" href="replication-options.html#sysvar_server_id">
<code class="literal">
server_id
</code>
</a>
explicitly to
specify a server ID.
</p>
<p>
For servers that are used in a replication topology, you must
specify a unique server ID for each replication server, in the range
from 1 to 2
<sup>
32
</sup>
− 1.
<span class="quote">
“
<span class="quote">
Unique
</span>
”
</span>
means that each ID must be different from
every other ID in use by any other source or replica in the
replication topology. For additional information, see
<a class="xref" href="replication-options-source.html" title="19.1.6.2 Replication Source Options and Variables">
Section 19.1.6.2, “Replication Source Options and Variables”
</a>
, and
<a class="xref" href="replication-options-replica.html" title="19.1.6.3 Replica Server Options and Variables">
Section 19.1.6.3, “Replica Server Options and Variables”
</a>
.
</p>
<p>
If the server ID is set to 0, binary logging takes place, but a
source with a server ID of 0 refuses any connections from replicas,
and a replica with a server ID of 0 refuses to connect to a source.
Note that although you can change the server ID dynamically to a
nonzero value, doing so does not enable replication to start
immediately. You must change the server ID and then restart the
server to initialize the replica.
</p>
<p>
For more information, see
<a class="xref" href="replication-howto-slavebaseconfig.html" title="19.1.2.2 Setting the Replica Configuration">
Section 19.1.2.2, “Setting the Replica Configuration”
</a>
.
</p>
<p>
<a name="sysvar_server_uuid">
</a>
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
</p>
<a class="indexterm" name="idm46045145048624">
</a>
<a class="indexterm" name="idm46045145047120">
</a>
<p>
The MySQL server generates a true UUID in addition to the default or
user-supplied server ID set in the
<code class="literal">
server_id
</code>
system variable. This is available as the global, read-only variable
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The presence of the
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
system variable does not change the requirement for setting a
unique
<a class="link" href="replication-options.html#sysvar_server_id">
<code class="literal">
server_id
</code>
</a>
value for each
MySQL server as part of preparing and running MySQL replication,
as described earlier in this section.
</p>
</div>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for server_uuid">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
System Variable
</th>
<td>
<code class="literal">
<a class="link" href="replication-options.html#sysvar_server_uuid">
server_uuid
</a>
</code>
</td>
</tr>
<tr>
<th>
Scope
</th>
<td>
Global
</td>
</tr>
<tr>
<th>
Dynamic
</th>
<td>
No
</td>
</tr>
<tr>
<th>
<a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax">
<code class="literal">
SET_VAR
</code>
</a>
Hint Applies
</th>
<td>
No
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<p>
When starting, the MySQL server automatically obtains a UUID as
follows:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
<a class="indexterm" name="idm46045145022624">
</a>
Attempt to read and use the UUID written in the file
<code class="filename">
<em class="replaceable">
<code>
data_dir
</code>
</em>
/auto.cnf
</code>
(where
<em class="replaceable">
<code>
data_dir
</code>
</em>
is the server's
data directory).
</p>
</li>
<li class="listitem">
<p>
If
<code class="filename">
<em class="replaceable">
<code>
data_dir
</code>
</em>
/auto.cnf
</code>
is not found, generate a new UUID and save it to this file,
creating the file if necessary.
</p>
</li>
</ol>
</div>
<p>
The
<code class="filename">
auto.cnf
</code>
file has a format similar to that
used for
<code class="filename">
my.cnf
</code>
or
<code class="filename">
my.ini
</code>
files.
<code class="filename">
auto.cnf
</code>
has only a single
<code class="literal">
[auto]
</code>
section containing a single
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
setting and value; the
file's contents appear similar to what is shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa70166310"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[auto]</span>
<span class="token constant">server_uuid</span><span class="token attr-value"><span class="token punctuation">=</span>8a94f357-aab4-11df-86ab-c80aa9429562</span></code></pre>
</div>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
The
<code class="filename">
auto.cnf
</code>
file is automatically generated;
do not attempt to write or modify this file.
</p>
</div>
<p>
When using MySQL replication, sources and replicas know each
other's UUIDs. The value of a replica's UUID can be seen
in the output of
<a class="link" href="show-replicas.html" title="15.7.7.36 SHOW REPLICAS Statement">
<code class="literal">
SHOW REPLICAS
</code>
</a>
. Once
<a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement">
<code class="literal">
START REPLICA
</code>
</a>
has been executed, the
value of the source's UUID is available on the replica in the
output of
<a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement">
<code class="literal">
SHOW REPLICA STATUS
</code>
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Issuing a
<a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement">
<code class="literal">
STOP REPLICA
</code>
</a>
or
<a class="link" href="reset-replica.html" title="15.4.2.3 RESET REPLICA Statement">
<code class="literal">
RESET REPLICA
</code>
</a>
statement does
<span class="emphasis">
<em>
not
</em>
</span>
reset the source's UUID as used on
the replica.
</p>
</div>
<p>
A server's
<code class="literal">
server_uuid
</code>
is also used in GTIDs
for transactions originating on that server. For more information,
see
<a class="xref" href="replication-gtids.html" title="19.1.3 Replication with Global Transaction Identifiers">
Section 19.1.3, “Replication with Global Transaction Identifiers”
</a>
.
</p>
<p>
When starting, the replication I/O (receiver) thread generates an
error and aborts if its source's UUID is equal to its own
unless the
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-same-server-id">
<code class="option">
--replicate-same-server-id
</code>
</a>
option has been set. In addition, the replication receiver thread
generates a warning if either of the following is true:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
No source having the expected
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
exists.
</p>
</li>
<li class="listitem">
<p>
The source's
<a class="link" href="replication-options.html#sysvar_server_uuid">
<code class="literal">
server_uuid
</code>
</a>
has changed, although no
<a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement">
<code class="literal">
CHANGE REPLICATION
SOURCE TO
</code>
</a>
statement has ever been executed.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/spatial-index-optimization.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="spatial-index-optimization">
</a>
10.3.3 SPATIAL Index Optimization
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045227504976">
</a>
<a class="indexterm" name="idm46045227503488">
</a>
<p>
MySQL permits creation of
<code class="literal">
SPATIAL
</code>
indexes on
<code class="literal">
NOT NULL
</code>
geometry-valued columns (see
<a class="xref" href="creating-spatial-indexes.html" title="13.4.10 Creating Spatial Indexes">
Section 13.4.10, “Creating Spatial Indexes”
</a>
). The optimizer
checks the
<code class="literal">
SRID
</code>
attribute for indexed columns
to determine which spatial reference system (SRS) to use for
comparisons, and uses calculations appropriate to the SRS.
(Prior to MySQL 8.4, the optimizer performs
comparisons of
<code class="literal">
SPATIAL
</code>
index values using
Cartesian calculations; the results of such operations are
undefined if the column contains values with non-Cartesian
SRIDs.)
</p>
<p>
For comparisons to work properly, each column in a
<code class="literal">
SPATIAL
</code>
index must be SRID-restricted. That
is, the column definition must include an explicit
<code class="literal">
SRID
</code>
attribute, and all column values must
have the same SRID.
</p>
<p>
The optimizer considers
<code class="literal">
SPATIAL
</code>
indexes only
for SRID-restricted columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Indexes on columns restricted to a Cartesian SRID enable
Cartesian bounding box computations.
</p>
</li>
<li class="listitem">
<p>
Indexes on columns restricted to a geographic SRID enable
geographic bounding box computations.
</p>
</li>
</ul>
</div>
<p>
The optimizer ignores
<code class="literal">
SPATIAL
</code>
indexes on
columns that have no
<code class="literal">
SRID
</code>
attribute (and thus
are not SRID-restricted). MySQL still maintains such indexes, as
follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
They are updated for table modifications
(
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
, and so forth).
Updates occur as though the index was Cartesian, even though
the column might contain a mix of Cartesian and geographical
values.
</p>
</li>
<li class="listitem">
<p>
They exist only for backward compatibility (for example, the
ability to perform a dump in MySQL
8.2 and restore in MySQL
8.3). Because
<code class="literal">
SPATIAL
</code>
indexes on columns that are not SRID-restricted are of no
use to the optimizer, each such column should be modified:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Verify that all values within the column have the same
SRID. To determine the SRIDs contained in a geometry
column
<em class="replaceable">
<code>
col_name
</code>
</em>
, use the
following query:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa79425927"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token keyword">DISTINCT</span> <span class="token function">ST_SRID</span><span class="token punctuation">(</span><em class="replaceable">col_name</em><span class="token punctuation">)</span> <span class="token keyword">FROM</span> <em class="replaceable">tbl_name</em><span class="token punctuation">;</span></code></pre>
</div>
<p>
If the query returns more than one row, the column
contains a mix of SRIDs. In that case, modify its
contents so all values have the same SRID.
</p>
</li>
<li class="listitem">
<p>
Redefine the column to have an explicit
<code class="literal">
SRID
</code>
attribute.
</p>
</li>
<li class="listitem">
<p>
Recreate the
<code class="literal">
SPATIAL
</code>
index.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/error-creating-innodb.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="error-creating-innodb">
</a>
17.20.1 Troubleshooting InnoDB I/O Problems
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045149035520">
</a>
<p>
The troubleshooting steps for
<code class="literal">
InnoDB
</code>
I/O
problems depend on when the problem occurs: during startup of the
MySQL server, or during normal operations when a DML or DDL
statement fails due to problems at the file system level.
</p>
<h4>
<a name="idm46045149032304">
</a>
Initialization Problems
</h4>
<p>
If something goes wrong when
<code class="literal">
InnoDB
</code>
attempts to
initialize its tablespace or its log files, delete all files
created by
<code class="literal">
InnoDB
</code>
: all
<code class="filename">
ibdata
</code>
files and all redo log files
(
<code class="filename">
#ib_redo
<em class="replaceable">
<code>
N
</code>
</em>
</code>
files).
If you created any
<code class="literal">
InnoDB
</code>
tables, also delete
any
<code class="filename">
.ibd
</code>
files from the MySQL database
directories. Then try initializing
<code class="literal">
InnoDB
</code>
again. For easiest troubleshooting, start the MySQL server from a
command prompt so that you see what is happening.
</p>
<h4>
<a name="idm46045149025584">
</a>
Runtime Problems
</h4>
<p>
If
<code class="literal">
InnoDB
</code>
prints an operating system error
during a file operation, usually the problem has one of the
following solutions:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Make sure the
<code class="literal">
InnoDB
</code>
data file directory
and the
<code class="literal">
InnoDB
</code>
log directory exist.
</p>
</li>
<li class="listitem">
<p>
Make sure
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
has access rights to
create files in those directories.
</p>
</li>
<li class="listitem">
<p>
Make sure
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
can read the proper
<code class="filename">
my.cnf
</code>
or
<code class="filename">
my.ini
</code>
option file, so that it starts with the options that you
specified.
</p>
</li>
<li class="listitem">
<p>
Make sure the disk is not full and you are not exceeding any
disk quota.
</p>
</li>
<li class="listitem">
<p>
Make sure that the names you specify for subdirectories and
data files do not clash.
</p>
</li>
<li class="listitem">
<p>
Doublecheck the syntax of the
<a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir">
<code class="literal">
innodb_data_home_dir
</code>
</a>
and
<a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path">
<code class="literal">
innodb_data_file_path
</code>
</a>
values.
In particular, any
<code class="literal">
MAX
</code>
value in the
<a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path">
<code class="literal">
innodb_data_file_path
</code>
</a>
option
is a hard limit, and exceeding that limit causes a fatal
error.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-auto-increment-handling.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="innodb-auto-increment-handling">
</a>
17.6.1.6 AUTO_INCREMENT Handling in InnoDB
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045166142864">
</a>
<a class="indexterm" name="idm46045166141792">
</a>
<p>
<code class="literal">
InnoDB
</code>
provides a configurable locking
mechanism that can significantly improve scalability and
performance of SQL statements that add rows to tables with
<code class="literal">
AUTO_INCREMENT
</code>
columns. To use the
<code class="literal">
AUTO_INCREMENT
</code>
mechanism with an
<code class="literal">
InnoDB
</code>
table, an
<code class="literal">
AUTO_INCREMENT
</code>
column must be defined as the
first or only column of some index such that it is possible to
perform the equivalent of an indexed
<code class="literal">
SELECT
MAX(
<em class="replaceable">
<code>
ai_col
</code>
</em>
)
</code>
lookup on the
table to obtain the maximum column value. The index is not
required to be a
<code class="literal">
PRIMARY KEY
</code>
or
<code class="literal">
UNIQUE
</code>
, but to avoid duplicate values in the
<code class="literal">
AUTO_INCREMENT
</code>
column, those index types are
recommended.
</p>
<p>
This section describes the
<code class="literal">
AUTO_INCREMENT
</code>
lock
modes, usage implications of different
<code class="literal">
AUTO_INCREMENT
</code>
lock mode settings, and how
<code class="literal">
InnoDB
</code>
initializes the
<code class="literal">
AUTO_INCREMENT
</code>
counter.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-modes" title="InnoDB AUTO_INCREMENT Lock Modes">
InnoDB AUTO_INCREMENT Lock Modes
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-mode-usage-implications" title="InnoDB AUTO_INCREMENT Lock Mode Usage Implications">
InnoDB AUTO_INCREMENT Lock Mode Usage Implications
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-initialization" title="InnoDB AUTO_INCREMENT Counter Initialization">
InnoDB AUTO_INCREMENT Counter Initialization
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-notes" title="Notes">
Notes
</a>
</p>
</li>
</ul>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="innodb-auto-increment-lock-modes">
</a>
InnoDB AUTO_INCREMENT Lock Modes
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045166123344">
</a>
<p>
This section describes the
<code class="literal">
AUTO_INCREMENT
</code>
lock modes used to generate auto-increment values, and how each
lock mode affects replication. The auto-increment lock mode is
configured at startup using the
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
variable.
</p>
<p>
The following terms are used in describing
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
settings:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements
</p>
<p>
All statements that generate new rows in a table, including
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE ...
SELECT
</code>
</a>
, and
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD
DATA
</code>
</a>
. Includes
<span class="quote">
“
<span class="quote">
simple-inserts
</span>
”
</span>
,
<span class="quote">
“
<span class="quote">
bulk-inserts
</span>
”
</span>
, and
<span class="quote">
“
<span class="quote">
mixed-mode
</span>
”
</span>
inserts.
</p>
</li>
<li class="listitem">
<p>
<span class="quote">
“
<span class="quote">
Simple inserts
</span>
”
</span>
</p>
<p>
Statements for which the number of rows to be inserted can
be determined in advance (when the statement is initially
processed). This includes single-row and multiple-row
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
and
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
statements that do
not have a nested subquery, but not
<a class="link" href="insert-on-duplicate.html" title="15.2.7.2 INSERT ... ON DUPLICATE KEY UPDATE Statement">
<code class="literal">
INSERT
... ON DUPLICATE KEY UPDATE
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<span class="quote">
“
<span class="quote">
Bulk inserts
</span>
”
</span>
</p>
<p>
Statements for which the number of rows to be inserted (and
the number of required auto-increment values) is not known
in advance. This includes
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE ...
SELECT
</code>
</a>
, and
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD
DATA
</code>
</a>
statements, but not plain
<code class="literal">
INSERT
</code>
.
<code class="literal">
InnoDB
</code>
assigns
new values for the
<code class="literal">
AUTO_INCREMENT
</code>
column
one at a time as each row is processed.
</p>
</li>
<li class="listitem">
<p>
<span class="quote">
“
<span class="quote">
Mixed-mode inserts
</span>
”
</span>
</p>
<p>
These are
<span class="quote">
“
<span class="quote">
simple insert
</span>
”
</span>
statements that
specify the auto-increment value for some (but not all) of
the new rows. An example follows, where
<code class="literal">
c1
</code>
is an
<code class="literal">
AUTO_INCREMENT
</code>
column of table
<code class="literal">
t1
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa27212827"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>c1<span class="token punctuation">,</span>c2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token string">'a'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'b'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token string">'c'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'d'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Another type of
<span class="quote">
“
<span class="quote">
mixed-mode insert
</span>
”
</span>
is
<a class="link" href="insert-on-duplicate.html" title="15.2.7.2 INSERT ... ON DUPLICATE KEY UPDATE Statement">
<code class="literal">
INSERT
... ON DUPLICATE KEY UPDATE
</code>
</a>
, which in the worst
case is in effect an
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
followed by a
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
, where
the allocated value for the
<code class="literal">
AUTO_INCREMENT
</code>
column may or may not be
used during the update phase.
</p>
</li>
</ul>
</div>
<p>
There are three possible settings for the
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
variable. The settings are 0, 1, or 2, for
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
,
<span class="quote">
“
<span class="quote">
consecutive
</span>
”
</span>
, or
<span class="quote">
“
<span class="quote">
interleaved
</span>
”
</span>
lock mode, respectively. Interleaved
lock mode
(
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode=2
</code>
</a>
) is
the default.
</p>
<p>
The default setting of interleaved lock mode in MySQL
8.4 reflects the change from statement-based
replication to row based replication as the default replication
type. Statement-based replication requires the consecutive
auto-increment lock mode to ensure that auto-increment values
are assigned in a predictable and repeatable order for a given
sequence of SQL statements, whereas row-based replication is not
sensitive to the execution order of SQL statements.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="innodb-auto-increment-lock-mode-traditional">
</a>
<code class="literal">
innodb_autoinc_lock_mode = 0
</code>
(
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
lock mode)
</p>
<p>
The traditional lock mode provides the same behavior that
existed before the
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
variable was introduced. The traditional lock mode option is
provided for backward compatibility, performance testing,
and working around issues with “mixed-mode inserts”, due
to possible differences in semantics.
</p>
<p>
In this lock mode, all
<span class="quote">
“
<span class="quote">
INSERT-like
</span>
”
</span>
statements
obtain a special table-level
<code class="literal">
AUTO-INC
</code>
lock for inserts into tables with
<code class="literal">
AUTO_INCREMENT
</code>
columns. This lock is
normally held to the end of the statement (not to the end of
the transaction) to ensure that auto-increment values are
assigned in a predictable and repeatable order for a given
sequence of
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements, and to ensure that auto-increment values
assigned by any given statement are consecutive.
</p>
<p>
In the case of statement-based replication, this means that
when an SQL statement is replicated on a replica server, the
same values are used for the auto-increment column as on the
source server. The result of execution of multiple
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements is
deterministic, and the replica reproduces the same data as
on the source. If auto-increment values generated by
multiple
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements
were interleaved, the result of two concurrent
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements would be
nondeterministic, and could not reliably be propagated to a
replica server using statement-based replication.
</p>
<p>
To make this clear, consider an example that uses this
table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa31005948"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
c1 <span class="token datatype">INT</span><span class="token punctuation">(</span><span class="token number">11</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span>
c2 <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span> <span class="token keyword">DEFAULT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>c1<span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre>
</div>
<p>
Suppose that there are two transactions running, each
inserting rows into a table with an
<code class="literal">
AUTO_INCREMENT
</code>
column. One transaction is
using an
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
statement that inserts 1000 rows, and
another is using a simple
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement that inserts
one row:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa62561032"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">Tx1: <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>c2<span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token number">1000</span> <span class="token keyword">rows</span> <span class="token keyword">from</span> another <span class="token keyword">table</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
Tx2: <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>c2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'xxx'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
<code class="literal">
InnoDB
</code>
cannot tell in advance how many
rows are retrieved from the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
in the
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement in Tx1, and
it assigns the auto-increment values one at a time as the
statement proceeds. With a table-level lock, held to the end
of the statement, only one
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement referring to
table
<code class="literal">
t1
</code>
can execute at a time, and the
generation of auto-increment numbers by different statements
is not interleaved. The auto-increment values generated by
the Tx1
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
statement are consecutive, and the (single)
auto-increment value used by the
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statement in Tx2 is
either smaller or larger than all those used for Tx1,
depending on which statement executes first.
</p>
<p>
As long as the SQL statements execute in the same order when
replayed from the binary log (when using statement-based
replication, or in recovery scenarios), the results are the
same as they were when Tx1 and Tx2 first ran. Thus,
table-level locks held until the end of a statement make
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements using
auto-increment safe for use with statement-based
replication. However, those table-level locks limit
concurrency and scalability when multiple transactions are
executing insert statements at the same time.
</p>
<p>
In the preceding example, if there were no table-level lock,
the value of the auto-increment column used for the
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
in Tx2 depends on
precisely when the statement executes. If the
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
of Tx2 executes while
the
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
of Tx1 is running
(rather than before it starts or after it completes), the
specific auto-increment values assigned by the two
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements are
nondeterministic, and may vary from run to run.
</p>
<p>
Under the
<a class="link" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-mode-consecutive">
consecutive
</a>
lock mode,
<code class="literal">
InnoDB
</code>
can avoid using
table-level
<code class="literal">
AUTO-INC
</code>
locks for
<span class="quote">
“
<span class="quote">
simple insert
</span>
”
</span>
statements where the number of
rows is known in advance, and still preserve deterministic
execution and safety for statement-based replication.
</p>
<p>
If you are not using the binary log to replay SQL statements
as part of recovery or replication, the
<a class="link" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-mode-interleaved">
interleaved
</a>
lock mode can be used to eliminate all use of table-level
<code class="literal">
AUTO-INC
</code>
locks for even greater
concurrency and performance, at the cost of permitting gaps
in auto-increment numbers assigned by a statement and
potentially having the numbers assigned by concurrently
executing statements interleaved.
</p>
</li>
<li class="listitem">
<p>
<a name="innodb-auto-increment-lock-mode-consecutive">
</a>
<code class="literal">
innodb_autoinc_lock_mode = 1
</code>
(
<span class="quote">
“
<span class="quote">
consecutive
</span>
”
</span>
lock mode)
</p>
<p>
In this mode,
<span class="quote">
“
<span class="quote">
bulk inserts
</span>
”
</span>
use the special
<code class="literal">
AUTO-INC
</code>
table-level lock and hold it
until the end of the statement. This applies to all
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE ...
SELECT
</code>
</a>
, and
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD
DATA
</code>
</a>
statements. Only one statement holding the
<code class="literal">
AUTO-INC
</code>
lock can execute at a time. If
the source table of the bulk insert operation is different
from the target table, the
<code class="literal">
AUTO-INC
</code>
lock
on the target table is taken after a shared lock is taken on
the first row selected from the source table. If the source
and target of the bulk insert operation are the same table,
the
<code class="literal">
AUTO-INC
</code>
lock is taken after shared
locks are taken on all selected rows.
</p>
<p>
<span class="quote">
“
<span class="quote">
Simple inserts
</span>
”
</span>
(for which the number of rows
to be inserted is known in advance) avoid table-level
<code class="literal">
AUTO-INC
</code>
locks by obtaining the required
number of auto-increment values under the control of a mutex
(a light-weight lock) that is only held for the duration of
the allocation process,
<span class="emphasis">
<em>
not
</em>
</span>
until the
statement completes. No table-level
<code class="literal">
AUTO-INC
</code>
lock is used unless an
<code class="literal">
AUTO-INC
</code>
lock is held by another
transaction. If another transaction holds an
<code class="literal">
AUTO-INC
</code>
lock, a
<span class="quote">
“
<span class="quote">
simple
insert
</span>
”
</span>
waits for the
<code class="literal">
AUTO-INC
</code>
lock, as if it were a
<span class="quote">
“
<span class="quote">
bulk insert
</span>
”
</span>
.
</p>
<p>
This lock mode ensures that, in the presence of
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements where the
number of rows is not known in advance (and where
auto-increment numbers are assigned as the statement
progresses), all auto-increment values assigned by any
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statement are consecutive, and operations are safe for
statement-based replication.
</p>
<p>
Simply put, this lock mode significantly improves
scalability while being safe for use with statement-based
replication. Further, as with
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
lock mode, auto-increment numbers assigned by any given
statement are
<span class="emphasis">
<em>
consecutive
</em>
</span>
. There is
<span class="emphasis">
<em>
no change
</em>
</span>
in semantics compared to
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
mode for any statement that uses
auto-increment, with one important exception.
</p>
<p>
The exception is for
<span class="quote">
“
<span class="quote">
mixed-mode inserts
</span>
”
</span>
,
where the user provides explicit values for an
<code class="literal">
AUTO_INCREMENT
</code>
column for some, but not
all, rows in a multiple-row
<span class="quote">
“
<span class="quote">
simple insert
</span>
”
</span>
.
For such inserts,
<code class="literal">
InnoDB
</code>
allocates more
auto-increment values than the number of rows to be
inserted. However, all values automatically assigned are
consecutively generated (and thus higher than) the
auto-increment value generated by the most recently executed
previous statement.
<span class="quote">
“
<span class="quote">
Excess
</span>
”
</span>
numbers are lost.
</p>
</li>
<li class="listitem">
<p>
<a name="innodb-auto-increment-lock-mode-interleaved">
</a>
<code class="literal">
innodb_autoinc_lock_mode = 2
</code>
(
<span class="quote">
“
<span class="quote">
interleaved
</span>
”
</span>
lock mode)
</p>
<p>
In this lock mode, no
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements use the table-level
<code class="literal">
AUTO-INC
</code>
lock, and multiple statements can execute at the same time.
This is the fastest and most scalable lock mode, but it is
<span class="emphasis">
<em>
not safe
</em>
</span>
when using statement-based
replication or recovery scenarios when SQL statements are
replayed from the binary log.
</p>
<p>
In this lock mode, auto-increment values are guaranteed to
be unique and monotonically increasing across all
concurrently executing
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements. However, because multiple statements can be
generating numbers at the same time (that is, allocation of
numbers is
<span class="emphasis">
<em>
interleaved
</em>
</span>
across
statements), the values generated for the rows inserted by
any given statement may not be consecutive.
</p>
<p>
If the only statements executing are
<span class="quote">
“
<span class="quote">
simple
inserts
</span>
”
</span>
where the number of rows to be inserted is
known ahead of time, there are no gaps in the numbers
generated for a single statement, except for
<span class="quote">
“
<span class="quote">
mixed-mode inserts
</span>
”
</span>
. However, when
<span class="quote">
“
<span class="quote">
bulk
inserts
</span>
”
</span>
are executed, there may be gaps in the
auto-increment values assigned by any given statement.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="innodb-auto-increment-lock-mode-usage-implications">
</a>
InnoDB AUTO_INCREMENT Lock Mode Usage Implications
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Using auto-increment with replication
</p>
<p>
If you are using statement-based replication, set
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
to
0 or 1 and use the same value on the source and its
replicas. Auto-increment values are not ensured to be the
same on the replicas as on the source if you use
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
=
2 (
<span class="quote">
“
<span class="quote">
interleaved
</span>
”
</span>
) or configurations where the
source and replicas do not use the same lock mode.
</p>
<p>
If you are using row-based or mixed-format replication, all
of the auto-increment lock modes are safe, since row-based
replication is not sensitive to the order of execution of
the SQL statements (and the mixed format uses row-based
replication for any statements that are unsafe for
statement-based replication).
</p>
</li>
<li class="listitem">
<p>
<span class="quote">
“
<span class="quote">
Lost
</span>
”
</span>
auto-increment values and sequence gaps
</p>
<p>
In all lock modes (0, 1, and 2), if a transaction that
generated auto-increment values rolls back, those
auto-increment values are
<span class="quote">
“
<span class="quote">
lost
</span>
”
</span>
. Once a value
is generated for an auto-increment column, it cannot be
rolled back, whether or not the
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statement is completed, and whether or not the containing
transaction is rolled back. Such lost values are not reused.
Thus, there may be gaps in the values stored in an
<code class="literal">
AUTO_INCREMENT
</code>
column of a table.
</p>
</li>
<li class="listitem">
<p>
Specifying NULL or 0 for the
<code class="literal">
AUTO_INCREMENT
</code>
column
</p>
<p>
In all lock modes (0, 1, and 2), if a user specifies NULL or
0 for the
<code class="literal">
AUTO_INCREMENT
</code>
column in an
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<code class="literal">
InnoDB
</code>
treats the row as if the value was
not specified and generates a new value for it.
</p>
</li>
<li class="listitem">
<p>
Assigning a negative value to the
<code class="literal">
AUTO_INCREMENT
</code>
column
</p>
<p>
In all lock modes (0, 1, and 2), the behavior of the
auto-increment mechanism is undefined if you assign a
negative value to the
<code class="literal">
AUTO_INCREMENT
</code>
column.
</p>
</li>
<li class="listitem">
<p>
If the
<code class="literal">
AUTO_INCREMENT
</code>
value becomes
larger than the maximum integer for the specified integer
type
</p>
<p>
In all lock modes (0, 1, and 2), the behavior of the
auto-increment mechanism is undefined if the value becomes
larger than the maximum integer that can be stored in the
specified integer type.
</p>
</li>
<li class="listitem">
<p>
Gaps in auto-increment values for
<span class="quote">
“
<span class="quote">
bulk
inserts
</span>
”
</span>
</p>
<p>
With
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
set to 0 (
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
) or 1
(
<span class="quote">
“
<span class="quote">
consecutive
</span>
”
</span>
), the auto-increment values
generated by any given statement are consecutive, without
gaps, because the table-level
<code class="literal">
AUTO-INC
</code>
lock is held until the end of the statement, and only one
such statement can execute at a time.
</p>
<p>
With
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
set to 2 (
<span class="quote">
“
<span class="quote">
interleaved
</span>
”
</span>
), there may be gaps in
the auto-increment values generated by
<span class="quote">
“
<span class="quote">
bulk
inserts,
</span>
”
</span>
but only if there are concurrently
executing
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements.
</p>
<p>
For lock modes 1 or 2, gaps may occur between successive
statements because for bulk inserts the exact number of
auto-increment values required by each statement may not be
known and overestimation is possible.
</p>
</li>
<li class="listitem">
<p>
Auto-increment values assigned by
<span class="quote">
“
<span class="quote">
mixed-mode
inserts
</span>
”
</span>
</p>
<p>
Consider a
<span class="quote">
“
<span class="quote">
mixed-mode insert,
</span>
”
</span>
where a
<span class="quote">
“
<span class="quote">
simple insert
</span>
”
</span>
specifies the auto-increment
value for some (but not all) resulting rows. Such a
statement behaves differently in lock modes 0, 1, and 2. For
example, assume
<code class="literal">
c1
</code>
is an
<code class="literal">
AUTO_INCREMENT
</code>
column of table
<code class="literal">
t1
</code>
, and that the most recent
automatically generated sequence number is 100.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa55248230"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
<span class="token prompt"> -></span> c1 <span class="token datatype">INT</span> <span class="token keyword">UNSIGNED</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> c2 <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token keyword">ENGINE</span> <span class="token operator">=</span> INNODB<span class="token punctuation">;</span></code></pre>
</div>
<p>
Now, consider the following
<span class="quote">
“
<span class="quote">
mixed-mode insert
</span>
”
</span>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa61634084"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>c1<span class="token punctuation">,</span>c2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token string">'a'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'b'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">,</span><span class="token string">'c'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'d'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
With
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
set to 0 (
<span class="quote">
“
<span class="quote">
traditional
</span>
”
</span>
), the four new rows
are:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa66739616"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1<span class="token punctuation">,</span> c2 <span class="token keyword">FROM</span> t1 <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> c2<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span> c2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> a <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> c <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 102 <span class="token punctuation">|</span> d <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The next available auto-increment value is 103 because the
auto-increment values are allocated one at a time, not all
at once at the beginning of statement execution. This result
is true whether or not there are concurrently executing
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements (of any type).
</p>
<p>
With
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
set to 1 (
<span class="quote">
“
<span class="quote">
consecutive
</span>
”
</span>
), the four new rows are
also:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa83473753"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1<span class="token punctuation">,</span> c2 <span class="token keyword">FROM</span> t1 <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> c2<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span> c2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> a <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> c <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 102 <span class="token punctuation">|</span> d <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
However, in this case, the next available auto-increment
value is 105, not 103 because four auto-increment values are
allocated at the time the statement is processed, but only
two are used. This result is true whether or not there are
concurrently executing
<span class="quote">
“
<span class="quote">
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
-like
</span>
”
</span>
statements (of any type).
</p>
<p>
With
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
set to 2 (
<span class="quote">
“
<span class="quote">
interleaved
</span>
”
</span>
), the four new rows
are:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa10706001"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1<span class="token punctuation">,</span> c2 <span class="token keyword">FROM</span> t1 <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> c2<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span> c2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> a <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> <em class="replaceable">x</em> <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> c <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> <em class="replaceable">y</em> <span class="token punctuation">|</span> d <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The values of
<em class="replaceable">
<code>
x
</code>
</em>
and
<em class="replaceable">
<code>
y
</code>
</em>
are unique and larger than any
previously generated rows. However, the specific values of
<em class="replaceable">
<code>
x
</code>
</em>
and
<em class="replaceable">
<code>
y
</code>
</em>
depend on the number of
auto-increment values generated by concurrently executing
statements.
</p>
<p>
Finally, consider the following statement, issued when the
most-recently generated sequence number is 100:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa31602546"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>c1<span class="token punctuation">,</span>c2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token string">'a'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'b'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">101</span><span class="token punctuation">,</span><span class="token string">'c'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">,</span><span class="token string">'d'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
With any
<a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode">
<code class="literal">
innodb_autoinc_lock_mode
</code>
</a>
setting, this statement generates a duplicate-key error
23000 (
<code class="literal">
Can't write; duplicate key in
table
</code>
) because 101 is allocated for the row
<code class="literal">
(NULL, 'b')
</code>
and insertion of the row
<code class="literal">
(101, 'c')
</code>
fails.
</p>
</li>
<li class="listitem">
<p>
Modifying
<code class="literal">
AUTO_INCREMENT
</code>
column values in
the middle of a sequence of
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements
</p>
<p>
If you modify an
<code class="literal">
AUTO_INCREMENT
</code>
column
value to a value larger than the current maximum
auto-increment value, the new value is persisted, and
subsequent
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
operations
allocate auto-increment values starting from the new, larger
value. This behavior is demonstrated in the following
example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa26811053"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
<span class="token prompt"> -></span> c1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>c1<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token keyword">ENGINE</span> <span class="token operator">=</span> InnoDB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> t1 <span class="token keyword">SET</span> c1 <span class="token operator">=</span> <span class="token number">4</span> <span class="token keyword">WHERE</span> c1 <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> c1 <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="innodb-auto-increment-initialization">
</a>
InnoDB AUTO_INCREMENT Counter Initialization
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045165912880">
</a>
<p>
This section describes how
<code class="literal">
InnoDB
</code>
initializes
<code class="literal">
AUTO_INCREMENT
</code>
counters.
</p>
<p>
If you specify an
<code class="literal">
AUTO_INCREMENT
</code>
column for
an
<code class="literal">
InnoDB
</code>
table, the in-memory table object
contains a special counter called the auto-increment counter
that is used when assigning new values for the column.
</p>
<p>
The current maximum auto-increment counter value is written to
the redo log each time it changes and saved to the data
dictionary on each checkpoint; this makes the current maximum
auto-increment counter value persistent across server restarts.
</p>
<p>
On a server restart following a normal shutdown,
<code class="literal">
InnoDB
</code>
initializes the in-memory
auto-increment counter using the current maximum auto-increment
value stored in the data dictionary.
</p>
<p>
On a server restart during crash recovery,
<code class="literal">
InnoDB
</code>
initializes the in-memory
auto-increment counter using the current maximum auto-increment
value stored in the data dictionary and scans the redo log for
auto-increment counter values written since the last checkpoint.
If a redo-logged value is greater than the in-memory counter
value, the redo-logged value is applied. However, in the case of
an unexpected server exit, reuse of a previously allocated
auto-increment value cannot be guaranteed. Each time the current
maximum auto-increment value is changed due to an
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
or
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
operation, the new value
is written to the redo log, but if the unexpected exit occurs
before the redo log is flushed to disk, the previously allocated
value could be reused when the auto-increment counter is
initialized after the server is restarted.
</p>
<p>
The only circumstance in which
<code class="literal">
InnoDB
</code>
uses
the equivalent of a
<code class="literal">
SELECT MAX(ai_col) FROM
<em class="replaceable">
<code>
table_name
</code>
</em>
FOR UPDATE
</code>
statement to initialize an auto-increment counter is when
<a class="link" href="innodb-table-import.html" title="17.6.1.3 Importing InnoDB Tables">
importing a table
</a>
without a
<code class="filename">
.cfg
</code>
metadata file. Otherwise,
the current maximum auto-increment counter value is read from
the
<code class="filename">
.cfg
</code>
metadata file if present. Aside
from counter value initialization, the equivalent of a
<code class="literal">
SELECT MAX(ai_col) FROM
<em class="replaceable">
<code>
table_name
</code>
</em>
</code>
statement is
used to determine the current maximum auto-increment counter
value of the table when attempting to set the counter value to
one that is smaller than or equal to the persisted counter value
using an
<code class="literal">
ALTER TABLE ... AUTO_INCREMENT =
<em class="replaceable">
<code>
N
</code>
</em>
</code>
statement. For example,
you might try to set the counter value to a lesser value after
deleting some records. In this case, the table must be searched
to ensure that the new counter value is not less than or equal
to the actual current maximum counter value.
</p>
<p>
A server restart does not cancel the effect of the
<code class="literal">
AUTO_INCREMENT = N
</code>
table option. If you
initialize the auto-increment counter to a specific value, or if
you alter the auto-increment counter value to a larger value,
the new value is persisted across server restarts.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE ...
AUTO_INCREMENT = N
</code>
</a>
can only change the
auto-increment counter value to a value larger than the
current maximum.
</p>
</div>
<p>
The current maximum auto-increment value is persisted,
preventing the reuse of previously allocated values.
</p>
<p>
If a
<a class="link" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement">
<code class="literal">
SHOW TABLE STATUS
</code>
</a>
statement
examines a table before the auto-increment counter is
initialized,
<code class="literal">
InnoDB
</code>
opens the table and
initializes the counter value using the current maximum
auto-increment value that is stored in the data dictionary. The
value is then stored in memory for use by later inserts or
updates. Initialization of the counter value uses a normal
exclusive-locking read on the table which lasts to the end of
the transaction.
<code class="literal">
InnoDB
</code>
follows the same
procedure when initializing the auto-increment counter for a
newly created table that has a user-specified auto-increment
value greater than 0.
</p>
<p>
After the auto-increment counter is initialized, if you do not
explicitly specify an auto-increment value when inserting a row,
<code class="literal">
InnoDB
</code>
implicitly increments the counter and
assigns the new value to the column. If you insert a row that
explicitly specifies an auto-increment column value, and the
value is greater than the current maximum counter value, the
counter is set to the specified value.
</p>
<p>
<code class="literal">
InnoDB
</code>
uses the in-memory auto-increment
counter as long as the server runs. When the server is stopped
and restarted,
<code class="literal">
InnoDB
</code>
reinitializes the
auto-increment counter, as described earlier.
</p>
<p>
The
<a class="link" href="replication-options-source.html#sysvar_auto_increment_offset">
<code class="literal">
auto_increment_offset
</code>
</a>
variable determines the starting point for the
<code class="literal">
AUTO_INCREMENT
</code>
column value. The default
setting is 1.
</p>
<p>
The
<a class="link" href="replication-options-source.html#sysvar_auto_increment_increment">
<code class="literal">
auto_increment_increment
</code>
</a>
variable controls the interval between successive column values.
The default setting is 1.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="innodb-auto-increment-notes">
</a>
Notes
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045165877088">
</a>
<a class="indexterm" name="idm46045165876016">
</a>
<p>
When an
<code class="literal">
AUTO_INCREMENT
</code>
integer column runs
out of values, a subsequent
<code class="literal">
INSERT
</code>
operation
returns a duplicate-key error. This is general MySQL behavior.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sys-wait-classes-global-by-avg-latency.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="sys-wait-classes-global-by-avg-latency">
</a>
30.4.3.48 The wait_classes_global_by_avg_latency and
x$wait_classes_global_by_avg_latency Views
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045061793232">
</a>
<a class="indexterm" name="idm46045061791776">
</a>
<a class="indexterm" name="idm46045061790272">
</a>
<a class="indexterm" name="idm46045061788752">
</a>
<p>
These views summarize wait class average latencies, grouped by
event class. By default, rows are sorted by descending average
latency. Idle events are ignored.
</p>
<p>
An event class is determined by stripping from the event name
everything after the first three components. For example, the
class for
<code class="literal">
wait/io/file/sql/slow_log
</code>
is
<code class="literal">
wait/io/file
</code>
.
</p>
<p>
The
<a class="link" href="sys-wait-classes-global-by-avg-latency.html" title="30.4.3.48 The wait_classes_global_by_avg_latency and x$wait_classes_global_by_avg_latency Views">
<code class="literal">
wait_classes_global_by_avg_latency
</code>
</a>
and
<a class="link" href="sys-wait-classes-global-by-avg-latency.html" title="30.4.3.48 The wait_classes_global_by_avg_latency and x$wait_classes_global_by_avg_latency Views">
<code class="literal">
x$wait_classes_global_by_avg_latency
</code>
</a>
views have these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
event_class
</code>
</p>
<p>
The event class.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
total
</code>
</p>
<p>
The total number of occurrences of events in the class.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
total_latency
</code>
</p>
<p>
The total wait time of timed occurrences of events in the
class.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
min_latency
</code>
</p>
<p>
The minimum single wait time of timed occurrences of
events in the class.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
avg_latency
</code>
</p>
<p>
The average wait time per timed occurrence of events in
the class.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
max_latency
</code>
</p>
<p>
The maximum single wait time of timed occurrences of
events in the class.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/uninstall-plugin.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="uninstall-plugin">
</a>
15.7.4.6 UNINSTALL PLUGIN Statement
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045171651328">
</a>
<a class="indexterm" name="idm46045171650272">
</a>
<a class="indexterm" name="idm46045171649200">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa5331755"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UNINSTALL</span> <span class="token keyword">PLUGIN</span> <em class="replaceable">plugin_name</em></code></pre>
</div>
<p>
This statement removes an installed server plugin.
<a class="link" href="uninstall-plugin.html" title="15.7.4.6 UNINSTALL PLUGIN Statement">
<code class="literal">
UNINSTALL PLUGIN
</code>
</a>
is the
complement of
<a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement">
<code class="literal">
INSTALL PLUGIN
</code>
</a>
. It
requires the
<a class="link" href="privileges-provided.html#priv_delete">
<code class="literal">
DELETE
</code>
</a>
privilege for
the
<code class="literal">
mysql.plugin
</code>
system table because it
removes the row from that table that registers the plugin.
</p>
<p>
<em class="replaceable">
<code>
plugin_name
</code>
</em>
must be the name of some
plugin that is listed in the
<code class="literal">
mysql.plugin
</code>
table. The server executes the plugin's deinitialization
function and removes the row for the plugin from the
<code class="literal">
mysql.plugin
</code>
system table, so that subsequent
server restarts do not load and initialize the plugin.
<a class="link" href="uninstall-plugin.html" title="15.7.4.6 UNINSTALL PLUGIN Statement">
<code class="literal">
UNINSTALL PLUGIN
</code>
</a>
does not remove
the plugin's shared library file.
</p>
<p>
You cannot uninstall a plugin if any table that uses it is open.
</p>
<p>
Plugin removal has implications for the use of associated
tables. For example, if a full-text parser plugin is associated
with a
<code class="literal">
FULLTEXT
</code>
index on the table,
uninstalling the plugin makes the table unusable. Any attempt to
access the table results in an error. The table cannot even be
opened, so you cannot drop an index for which the plugin is
used. This means that uninstalling a plugin is something to do
with care unless you do not care about the table contents. If
you are uninstalling a plugin with no intention of reinstalling
it later and you care about the table contents, you should dump
the table with
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
and remove the
<code class="literal">
WITH PARSER
</code>
clause from the dumped
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statement so that
you can reload the table later. If you do not care about the
table,
<a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
<code class="literal">
DROP TABLE
</code>
</a>
can be used
even if any plugins associated with the table are missing.
</p>
<p>
For additional information about plugin loading, see
<a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins">
Section 7.6.1, “Installing and Uninstalling Plugins”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/server-loadable-functions.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="server-loadable-functions">
</a>
7.7 MySQL Server Loadable Functions
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="function-loading.html">
7.7.1 Installing and Uninstalling Loadable Functions
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="obtaining-loadable-function-information.html">
7.7.2 Obtaining Information About Loadable Functions
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045254244496">
</a>
<a class="indexterm" name="idm46045254243424">
</a>
<a class="indexterm" name="idm46045254241936">
</a>
<p>
MySQL supports loadable functions, that is, functions that are not
built in but can be loaded at runtime (either during startup or
later) to extend server capabilities, or unloaded to remove
capabilities. For a table describing the available loadable
functions, see
<a class="xref" href="loadable-function-reference.html" title="14.2 Loadable Function Reference">
Section 14.2, “Loadable Function Reference”
</a>
.
Loadable functions contrast with built-in (native) functions, which
are implemented as part of the server and are always available; for
a table, see
<a class="xref" href="built-in-function-reference.html" title="14.1 Built-In Function and Operator Reference">
Section 14.1, “Built-In Function and Operator Reference”
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Loadable functions previously were known as user-defined functions
(UDFs). That terminology was something of a misnomer because
<span class="quote">
“
<span class="quote">
user-defined
</span>
”
</span>
also can apply to other types of
functions, such as stored functions (a type of stored object
written using SQL) and native functions added by modifying the
server source code.
</p>
</div>
<p>
MySQL distributions include loadable functions that implement, in
whole or in part, these server capabilities:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Group Replication enables you to create a highly available
distributed MySQL service across a group of MySQL server
instances, with data consistency, conflict detection and
resolution, and group membership services all built-in. See
<a class="xref" href="group-replication.html" title="Chapter 20 Group Replication">
Chapter 20,
<i>
Group Replication
</i>
</a>
.
</p>
</li>
<li class="listitem">
<p>
MySQL Enterprise Edition includes functions that perform encryption operations
based on the OpenSSL library. See
<a class="xref" href="enterprise-encryption.html" title="8.6 MySQL Enterprise Encryption">
Section 8.6, “MySQL Enterprise Encryption”
</a>
.
</p>
</li>
<li class="listitem">
<p>
MySQL Enterprise Edition includes functions that provide an SQL-level API for
masking and de-identification operations. See
<a class="xref" href="data-masking.html" title="8.5 MySQL Enterprise Data Masking and De-Identification">
Section 8.5, “MySQL Enterprise Data Masking and De-Identification”
</a>
.
</p>
</li>
<li class="listitem">
<p>
MySQL Enterprise Edition includes audit logging for monitoring and logging of
connection and query activity. See
<a class="xref" href="audit-log.html" title="8.4.5 MySQL Enterprise Audit">
Section 8.4.5, “MySQL Enterprise Audit”
</a>
,
and
<a class="xref" href="audit-api-message-emit.html" title="8.4.6 The Audit Message Component">
Section 8.4.6, “The Audit Message Component”
</a>
.
</p>
</li>
<li class="listitem">
<p>
MySQL Enterprise Edition includes a firewall capability that implements an
application-level firewall to enable database administrators to
permit or deny SQL statement execution based on matching against
patterns for accepted statement. See
<a class="xref" href="firewall.html" title="8.4.7 MySQL Enterprise Firewall">
Section 8.4.7, “MySQL Enterprise Firewall”
</a>
.
</p>
</li>
<li class="listitem">
<p>
A query rewriter examines statements received by MySQL Server
and possibly rewrites them before the server executes them. See
<a class="xref" href="rewriter-query-rewrite-plugin.html" title="7.6.4 The Rewriter Query Rewrite Plugin">
Section 7.6.4, “The Rewriter Query Rewrite Plugin”
</a>
</p>
</li>
<li class="listitem">
<p>
Version Tokens enables creation of and synchronization around
server tokens that applications can use to prevent accessing
incorrect or out-of-date data. See
<a class="xref" href="version-tokens.html" title="7.6.6 Version Tokens">
Section 7.6.6, “Version Tokens”
</a>
.
</p>
</li>
<li class="listitem">
<p>
The MySQL Keyring provides secure storage for sensitive
information. See
<a class="xref" href="keyring.html" title="8.4.4 The MySQL Keyring">
Section 8.4.4, “The MySQL Keyring”
</a>
.
</p>
</li>
<li class="listitem">
<p>
A locking service provides a locking interface for application
use. See
<a class="xref" href="locking-service.html" title="7.6.9.1 The Locking Service">
Section 7.6.9.1, “The Locking Service”
</a>
.
</p>
</li>
<li class="listitem">
<p>
A function provides access to query attributes. See
<a class="xref" href="query-attributes.html" title="11.6 Query Attributes">
Section 11.6, “Query Attributes”
</a>
.
</p>
</li>
</ul>
</div>
<p>
The following sections describe how to install and uninstall
loadable functions, and how to determine at runtime which loadable
functions are installed and obtain information about them.
</p>
<p>
In some cases, a loadable function is loaded by installing the
component that implements the function, rather than by loading the
function directly. For details about a particular loadable function,
see the installation instructions for the server feature that
includes it.
</p>
<a class="indexterm" name="idm46045254217280">
</a>
<p>
For information about writing loadable functions, see
<a class="ulink" href="/doc/extending-mysql/8.4/en/adding-functions.html" target="_top">
Adding Functions to MySQL
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/connector-net-info.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="connector-net-info">
</a>
31.3 MySQL Connector/NET
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045060377120">
</a>
<p>
The MySQL Connector/NET manual is published in standalone form, not as part of
the MySQL Reference Manual. For information, see these documents:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Main manual:
<a class="ulink" href="/doc/connector-net/en/" target="_top">
MySQL Connector/NET Developer Guide
</a>
</p>
</li>
<li class="listitem">
<p>
Release notes:
<a class="ulink" href="/doc/relnotes/connector-net/en/" target="_top">
MySQL Connector/NET
Release Notes
</a>
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/numeric-types.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="numeric-types">
</a>
13.1 Numeric Data Types
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="numeric-type-syntax.html">
13.1.1 Numeric Data Type Syntax
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="integer-types.html">
13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT,
MEDIUMINT, BIGINT
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="fixed-point-types.html">
13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="floating-point-types.html">
13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="bit-type.html">
13.1.5 Bit-Value Type - BIT
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="numeric-type-attributes.html">
13.1.6 Numeric Type Attributes
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="out-of-range-and-overflow.html">
13.1.7 Out-of-Range and Overflow Handling
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045214461024">
</a>
<a class="indexterm" name="idm46045214459536">
</a>
<a class="indexterm" name="idm46045214458048">
</a>
<p>
MySQL supports all standard SQL numeric data types. These types
include the exact numeric data types
(
<a class="link" href="integer-types.html" title="13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT">
<code class="literal">
INTEGER
</code>
</a>
,
<a class="link" href="integer-types.html" title="13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT">
<code class="literal">
SMALLINT
</code>
</a>
,
<a class="link" href="fixed-point-types.html" title="13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC">
<code class="literal">
DECIMAL
</code>
</a>
, and
<a class="link" href="fixed-point-types.html" title="13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC">
<code class="literal">
NUMERIC
</code>
</a>
), as well as the
approximate numeric data types
(
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
FLOAT
</code>
</a>
,
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
REAL
</code>
</a>
, and
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
DOUBLE PRECISION
</code>
</a>
). The keyword
<a class="link" href="integer-types.html" title="13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT">
<code class="literal">
INT
</code>
</a>
is a synonym for
<a class="link" href="integer-types.html" title="13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT">
<code class="literal">
INTEGER
</code>
</a>
, and the keywords
<a class="link" href="fixed-point-types.html" title="13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC">
<code class="literal">
DEC
</code>
</a>
and
<a class="link" href="fixed-point-types.html" title="13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC">
<code class="literal">
FIXED
</code>
</a>
are synonyms for
<a class="link" href="fixed-point-types.html" title="13.1.3 Fixed-Point Types (Exact Value) - DECIMAL, NUMERIC">
<code class="literal">
DECIMAL
</code>
</a>
. MySQL treats
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
DOUBLE
</code>
</a>
as a synonym for
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
DOUBLE PRECISION
</code>
</a>
(a nonstandard
extension). MySQL also treats
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
REAL
</code>
</a>
as a synonym for
<a class="link" href="floating-point-types.html" title="13.1.4 Floating-Point Types (Approximate Value) - FLOAT, DOUBLE">
<code class="literal">
DOUBLE PRECISION
</code>
</a>
(a nonstandard variation), unless the
<a class="link" href="sql-mode.html#sqlmode_real_as_float">
<code class="literal">
REAL_AS_FLOAT
</code>
</a>
SQL mode is
enabled.
</p>
<p>
The
<a class="link" href="bit-type.html" title="13.1.5 Bit-Value Type - BIT">
<code class="literal">
BIT
</code>
</a>
data type stores bit values
and is supported for
<a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine">
<code class="literal">
MyISAM
</code>
</a>
,
<a class="link" href="memory-storage-engine.html" title="18.3 The MEMORY Storage Engine">
<code class="literal">
MEMORY
</code>
</a>
,
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
, and
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
tables.
</p>
<p>
For information about how MySQL handles assignment of out-of-range
values to columns and overflow during expression evaluation, see
<a class="xref" href="out-of-range-and-overflow.html" title="13.1.7 Out-of-Range and Overflow Handling">
Section 13.1.7, “Out-of-Range and Overflow Handling”
</a>
.
</p>
<p>
For information about storage requirements of the numeric data
types, see
<a class="xref" href="storage-requirements.html" title="13.7 Data Type Storage Requirements">
Section 13.7, “Data Type Storage Requirements”
</a>
.
</p>
<p>
For descriptions of functions that operate on numeric values, see
<a class="xref" href="numeric-functions.html" title="14.6 Numeric Functions and Operators">
Section 14.6, “Numeric Functions and Operators”
</a>
. The data type used for the
result of a calculation on numeric operands depends on the types
of the operands and the operations performed on them. For more
information, see
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-disk-write-speed-aggregate-node.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-ndbinfo-disk-write-speed-aggregate-node">
</a>
25.6.17.30 The ndbinfo disk_write_speed_aggregate_node Table
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045089469440">
</a>
<p>
The
<code class="literal">
disk_write_speed_aggregate_node
</code>
table
provides aggregated information per node about the speed of disk
writes during LCP, backup, and restore operations.
</p>
<p>
The
<code class="literal">
disk_write_speed_aggregate_node
</code>
table
contains the following columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
node_id
</code>
</p>
<p>
Node ID of this node
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
backup_lcp_speed_last_sec
</code>
</p>
<p>
Number of bytes written to disk by backup and LCP processes
in the last second
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redo_speed_last_sec
</code>
</p>
<p>
Number of bytes written to the redo log in the last second
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
backup_lcp_speed_last_10sec
</code>
</p>
<p>
Number of bytes written to disk by backup and LCP processes
per second, averaged over the last 10 seconds
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redo_speed_last_10sec
</code>
</p>
<p>
Number of bytes written to the redo log each second,
averaged over the last 10 seconds
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
backup_lcp_speed_last_60sec
</code>
</p>
<p>
Number of bytes written to disk by backup and LCP processes
per second, averaged over the last 60 seconds
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redo_speed_last_60sec
</code>
</p>
<p>
Number of bytes written to the redo log each second,
averaged over the last 60 seconds
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-file-defragmenting.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="innodb-file-defragmenting">
</a>
17.11.4 Defragmenting a Table
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045160615744">
</a>
<a class="indexterm" name="idm46045160613840">
</a>
<p>
Random insertions into or deletions from a secondary index can
cause the index to become fragmented. Fragmentation means that the
physical ordering of the index pages on the disk is not close to
the index ordering of the records on the pages, or that there are
many unused pages in the 64-page blocks that were allocated to the
index.
</p>
<p>
One symptom of fragmentation is that a table takes more space than
it
<span class="quote">
“
<span class="quote">
should
</span>
”
</span>
take. How much that is exactly, is
difficult to determine. All
<code class="literal">
InnoDB
</code>
data and
indexes are stored in
<a class="link" href="glossary.html#glos_b_tree" title="B-tree">
B-trees
</a>
,
and their
<a class="link" href="glossary.html#glos_fill_factor" title="fill factor">
fill factor
</a>
may
vary from 50% to 100%. Another symptom of fragmentation is that a
table scan such as this takes more time than it
<span class="quote">
“
<span class="quote">
should
</span>
”
</span>
take:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa74918548"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token function">COUNT</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> t <span class="token keyword">WHERE</span> <em class="replaceable">non_indexed_column</em> <span class="token operator"><></span> <span class="token number">12345</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
The preceding query requires MySQL to perform a full table scan,
the slowest type of query for a large table.
</p>
<p>
To speed up index scans, you can periodically perform a
<span class="quote">
“
<span class="quote">
null
</span>
”
</span>
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
operation, which causes MySQL to rebuild the table:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa48580377"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> <em class="replaceable">tbl_name</em> <span class="token keyword">ENGINE</span><span class="token operator">=</span>INNODB</code></pre>
</div>
<p>
You can also use
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
<em class="replaceable">
<code>
tbl_name
</code>
</em>
FORCE
</code>
</a>
to perform a
<span class="quote">
“
<span class="quote">
null
</span>
”
</span>
alter operation that rebuilds the table.
</p>
<p>
Both
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
<em class="replaceable">
<code>
tbl_name
</code>
</em>
ENGINE=INNODB
</code>
</a>
and
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
<em class="replaceable">
<code>
tbl_name
</code>
</em>
FORCE
</code>
</a>
use
<a class="link" href="innodb-online-ddl.html" title="17.12 InnoDB and Online DDL">
online DDL
</a>
. For more
information, see
<a class="xref" href="innodb-online-ddl.html" title="17.12 InnoDB and Online DDL">
Section 17.12, “InnoDB and Online DDL”
</a>
.
</p>
<p>
Another way to perform a defragmentation operation is to use
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
to dump the table to a text file,
drop the table, and reload it from the dump file.
</p>
<p>
If the insertions into an index are always ascending and records
are deleted only from the end, the
<code class="literal">
InnoDB
</code>
filespace management algorithm guarantees that fragmentation in
the index does not occur.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/x-plugin-options-variables.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="x-plugin-options-variables">
</a>
22.5.6 X Plugin Options and Variables
</h3>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="x-plugin-option-variable-reference.html">
22.5.6.1 X Plugin Option and Variable Reference
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="x-plugin-options-system-variables.html">
22.5.6.2 X Plugin Options and System Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="x-plugin-status-variables.html">
22.5.6.3 X Plugin Status Variables
</a>
</span>
</dt>
</dl>
</div>
<p>
This section describes the command options and system variables
that configure X Plugin, as well as the status variables
available for monitoring purposes. If configuration values
specified at startup time are incorrect, X Plugin could fail to
initialize properly and the server does not load it. In this case,
the server could also produce error messages for other X Plugin
settings because it cannot recognize them.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-shell-tutorial-python-documents-find.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-shell-tutorial-python-documents-find">
</a>
22.4.3.3 Find Documents
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127179840">
</a>
<p>
You can use the
<code class="literal">
find()
</code>
method to query for
and return documents from a collection in a schema. MySQL Shell
provides additional methods to use with the
<code class="literal">
find()
</code>
method to filter and sort the returned
documents.
</p>
<p>
MySQL provides the following operators to specify search
conditions:
<code class="literal">
OR
</code>
(
<code class="literal">
||
</code>
),
<code class="literal">
AND
</code>
(
<code class="literal">
&&
</code>
),
<code class="literal">
XOR
</code>
,
<code class="literal">
IS
</code>
,
<code class="literal">
NOT
</code>
,
<code class="literal">
BETWEEN
</code>
,
<code class="literal">
IN
</code>
,
<code class="literal">
LIKE
</code>
,
<code class="literal">
!=
</code>
,
<code class="literal">
<>
</code>
,
<code class="literal">
>
</code>
,
<code class="literal">
>=
</code>
,
<code class="literal">
<
</code>
,
<code class="literal">
<=
</code>
,
<code class="literal">
&
</code>
,
<code class="literal">
|
</code>
,
<code class="literal">
<<
</code>
,
<code class="literal">
>>
</code>
,
<code class="literal">
+
</code>
,
<code class="literal">
-
</code>
,
<code class="literal">
*
</code>
,
<code class="literal">
/
</code>
,
<code class="literal">
~
</code>
, and
<code class="literal">
%
</code>
.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="mysql-shell-tutorial-python-documents-find-all">
</a>
Find All Documents in a Collection
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127156704">
</a>
<p>
To return all documents in a collection, use the
<code class="literal">
find()
</code>
method without specifying search
conditions. For example, the following operation returns all
documents in the
<code class="literal">
countryinfo
</code>
collection.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa19345299"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">[</span>
<span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">828</span><span class="token punctuation">,</span>
<span class="token property">"Code:"</span><span class="token operator">:</span> <span class="token string">"ABW"</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"Aruba"</span><span class="token punctuation">,</span>
<span class="token property">"IndepYear"</span><span class="token operator">:</span> <span class="token null">null</span><span class="token punctuation">,</span>
<span class="token property">"geography"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Continent"</span><span class="token operator">:</span> <span class="token string">"North America"</span><span class="token punctuation">,</span>
<span class="token property">"Region"</span><span class="token operator">:</span> <span class="token string">"Caribbean"</span><span class="token punctuation">,</span>
<span class="token property">"SurfaceArea"</span><span class="token operator">:</span> <span class="token number">193</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"government"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"GovernmentForm"</span><span class="token operator">:</span> <span class="token string">"Nonmetropolitan Territory of The Netherlands"</span><span class="token punctuation">,</span>
<span class="token property">"HeadOfState"</span><span class="token operator">:</span> <span class="token string">"Beatrix"</span>
<span class="token punctuation">}</span>
<span class="token property">"demographics"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"LifeExpectancy"</span><span class="token operator">:</span> <span class="token number">78.4000015258789</span><span class="token punctuation">,</span>
<span class="token property">"Population"</span><span class="token operator">:</span> <span class="token number">103000</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
...
<span class="token punctuation">}</span>
<span class="token punctuation">]</span></span>
<span class="token output">240 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
The method produces results that contain operational
information in addition to all documents in the collection.
</p>
<p>
An empty set (no matching documents) returns the following
information:
</p>
<pre class="screen">Empty set (0.00 sec)
</pre>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="mysql-shell-tutorial-python-documents-find-filter-searches">
</a>
Filter Searches
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127147856">
</a>
<p>
You can include search conditions with the
<code class="literal">
find()
</code>
method. The syntax for expressions
that form a search condition is the same as that of
traditional MySQL
<a class="xref" href="functions.html" title="Chapter 14 Functions and Operators">
Chapter 14,
<i>
Functions and Operators
</i>
</a>
. You must
enclose all expressions in quotes. For the sake of brevity,
some of the examples do not display output.
</p>
<p>
A simple search condition could consist of the
<code class="literal">
Name
</code>
field and a value we know is in a
document. The following example returns a single document:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa78262362"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"Name = 'Australia'"</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">[</span>
<span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">351182</span><span class="token punctuation">,</span>
<span class="token property">"Code:"</span><span class="token operator">:</span> <span class="token string">"AUS"</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"Australia"</span><span class="token punctuation">,</span>
<span class="token property">"IndepYear"</span><span class="token operator">:</span> <span class="token number">1901</span><span class="token punctuation">,</span>
<span class="token property">"geography"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Continent"</span><span class="token operator">:</span> <span class="token string">"Oceania"</span><span class="token punctuation">,</span>
<span class="token property">"Region"</span><span class="token operator">:</span> <span class="token string">"Australia and New Zealand"</span><span class="token punctuation">,</span>
<span class="token property">"SurfaceArea"</span><span class="token operator">:</span> <span class="token number">7741220</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"government"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"GovernmentForm"</span><span class="token operator">:</span> <span class="token string">"Constitutional Monarchy, Federation"</span><span class="token punctuation">,</span>
<span class="token property">"HeadOfState"</span><span class="token operator">:</span> <span class="token string">"Elisabeth II"</span>
<span class="token punctuation">}</span>
<span class="token property">"demographics"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"LifeExpectancy"</span><span class="token operator">:</span> <span class="token number">79.80000305175781</span><span class="token punctuation">,</span>
<span class="token property">"Population"</span><span class="token operator">:</span> <span class="token number">18886000</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span>
<span class="token punctuation">]</span></span></code></pre>
</div>
<p>
The following example searches for all countries that have a
GNP higher than $500 billion. The
<code class="literal">
countryinfo
</code>
collection measures GNP in
units of million.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa161517"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"GNP > 500000"</span><span class="token punctuation">)</span>
<span class="token operator">...</span><span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">10 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
The Population field in the following query is embedded within
the demographics object. To access the embedded field, use a
period between demographics and Population to identify the
relationship. Document and field names are case-sensitive.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa66592794"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"GNP > 500000 and demographics.Population < 100000000"</span><span class="token punctuation">)</span>
<span class="token operator">...</span><span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">6 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
Arithmetic operators in the following expression are used to
query for countries with a GNP per capita higher than $30000.
Search conditions can include arithmetic operators and most
MySQL functions.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Seven documents in the
<code class="literal">
countryinfo
</code>
collection have a population value of zero. Therefore
warning messages appear at the end of the output.
</p>
</div>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa519534"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"GNP*1000000/demographics.Population > 30000"</span><span class="token punctuation">)</span>
<span class="token operator">...</span><span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">9 documents in set, 7 warnings (0.00 sec)</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span>
Warning <span class="token punctuation">(</span>Code <span class="token number">1365</span><span class="token punctuation">)</span><span class="token punctuation">:</span> Division by <span class="token number">0</span></code></pre>
</div>
<p>
You can separate a value from the search condition by using
the
<code class="literal">
bind()
</code>
method. For example, instead of
specifying a hard-coded country name as the condition,
substitute a named placeholder consisting of a colon followed
by a name that begins with a letter, such as
<span class="emphasis">
<em>
country
</em>
</span>
. Then use the
<code class="literal">
bind(
<em class="replaceable">
<code>
placeholder
</code>
</em>
,
<em class="replaceable">
<code>
value
</code>
</em>
)
</code>
method as follows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa20709129"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"Name = :country"</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token string">"country"</span><span class="token punctuation">,</span> <span class="token string">"Italy"</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">1161755</span><span class="token punctuation">,</span>
<span class="token property">"_id"</span><span class="token operator">:</span> <span class="token string">"00005de917d8000000000000006a"</span><span class="token punctuation">,</span>
<span class="token property">"Code"</span><span class="token operator">:</span> <span class="token string">"ITA"</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"Italy"</span><span class="token punctuation">,</span>
<span class="token property">"Airports"</span><span class="token operator">:</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
<span class="token property">"IndepYear"</span><span class="token operator">:</span> <span class="token number">1861</span><span class="token punctuation">,</span>
<span class="token property">"geography"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Region"</span><span class="token operator">:</span> <span class="token string">"Southern Europe"</span><span class="token punctuation">,</span>
<span class="token property">"Continent"</span><span class="token operator">:</span> <span class="token string">"Europe"</span><span class="token punctuation">,</span>
<span class="token property">"SurfaceArea"</span><span class="token operator">:</span> <span class="token number">301316</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"government"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"HeadOfState"</span><span class="token operator">:</span> <span class="token string">"Carlo Azeglio Ciampi"</span><span class="token punctuation">,</span>
<span class="token property">"GovernmentForm"</span><span class="token operator">:</span> <span class="token string">"Republic"</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"demographics"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Population"</span><span class="token operator">:</span> <span class="token number">57680000</span><span class="token punctuation">,</span>
<span class="token property">"LifeExpectancy"</span><span class="token operator">:</span> <span class="token number">79</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></span>
<span class="token output">1 document in set (0.01 sec)</span></code></pre>
</div>
<div class="tip" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Tip
</div>
<p>
Within a program, binding enables you to specify
placeholders in your expressions, which are filled in with
values before execution and can benefit from automatic
escaping, as appropriate.
</p>
<p>
Always use binding to sanitize input. Avoid introducing
values in queries using string concatenation, which can
produce invalid input and, in some cases, can cause security
issues.
</p>
</div>
<p>
You can use placeholders and the
<code class="literal">
bind()
</code>
method to create saved searches which you can then call with
different values. For example to create a saved search for a
country:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa33728926"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> myFind <span class="token operator">=</span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"Name = :country"</span><span class="token punctuation">)</span>
<span class="token prompt">mysql-py></span> myFind<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token string">'country'</span><span class="token punctuation">,</span> <span class="token string">'France'</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">1424285</span><span class="token punctuation">,</span>
<span class="token property">"_id"</span><span class="token operator">:</span> <span class="token string">"00005de917d80000000000000048"</span><span class="token punctuation">,</span>
<span class="token property">"Code"</span><span class="token operator">:</span> <span class="token string">"FRA"</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"France"</span><span class="token punctuation">,</span>
<span class="token property">"IndepYear"</span><span class="token operator">:</span> <span class="token number">843</span><span class="token punctuation">,</span>
<span class="token property">"geography"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Region"</span><span class="token operator">:</span> <span class="token string">"Western Europe"</span><span class="token punctuation">,</span>
<span class="token property">"Continent"</span><span class="token operator">:</span> <span class="token string">"Europe"</span><span class="token punctuation">,</span>
<span class="token property">"SurfaceArea"</span><span class="token operator">:</span> <span class="token number">551500</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"government"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"HeadOfState"</span><span class="token operator">:</span> <span class="token string">"Jacques Chirac"</span><span class="token punctuation">,</span>
<span class="token property">"GovernmentForm"</span><span class="token operator">:</span> <span class="token string">"Republic"</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"demographics"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Population"</span><span class="token operator">:</span> <span class="token number">59225700</span><span class="token punctuation">,</span>
<span class="token property">"LifeExpectancy"</span><span class="token operator">:</span> <span class="token number">78.80000305175781</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></span>
<span class="token output">1 document in set (0.0028 sec)</span>
<span class="token prompt">mysql-py></span> myFind<span class="token punctuation">.</span><span class="token function">bind</span><span class="token punctuation">(</span><span class="token string">'country'</span><span class="token punctuation">,</span> <span class="token string">'Germany'</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">2133367</span><span class="token punctuation">,</span>
<span class="token property">"_id"</span><span class="token operator">:</span> <span class="token string">"00005de917d80000000000000038"</span><span class="token punctuation">,</span>
<span class="token property">"Code"</span><span class="token operator">:</span> <span class="token string">"DEU"</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"Germany"</span><span class="token punctuation">,</span>
<span class="token property">"IndepYear"</span><span class="token operator">:</span> <span class="token number">1955</span><span class="token punctuation">,</span>
<span class="token property">"geography"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Region"</span><span class="token operator">:</span> <span class="token string">"Western Europe"</span><span class="token punctuation">,</span>
<span class="token property">"Continent"</span><span class="token operator">:</span> <span class="token string">"Europe"</span><span class="token punctuation">,</span>
<span class="token property">"SurfaceArea"</span><span class="token operator">:</span> <span class="token number">357022</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"government"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"HeadOfState"</span><span class="token operator">:</span> <span class="token string">"Johannes Rau"</span><span class="token punctuation">,</span>
<span class="token property">"GovernmentForm"</span><span class="token operator">:</span> <span class="token string">"Federal Republic"</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token property">"demographics"</span><span class="token operator">:</span> <span class="token punctuation">{</span>
<span class="token property">"Population"</span><span class="token operator">:</span> <span class="token number">82164700</span><span class="token punctuation">,</span>
<span class="token property">"LifeExpectancy"</span><span class="token operator">:</span> <span class="token number">77.4000015258789</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></span>
<span class="token output">1 document in set (0.0026 sec)</span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="idm46045127116016">
</a>
Project Results
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127115344">
</a>
<p>
You can return specific fields of a document, instead of
returning all the fields. The following example returns the
GNP and Name fields of all documents in the
<code class="literal">
countryinfo
</code>
collection matching the search
conditions.
</p>
<p>
Use the
<code class="literal">
fields()
</code>
method to pass the list of
fields to return.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa97442360"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"GNP > 5000000"</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">fields</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token string">"GNP"</span><span class="token punctuation">,</span> <span class="token string">"Name"</span><span class="token punctuation">]</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">[</span>
<span class="token punctuation">{</span>
<span class="token property">"GNP"</span><span class="token operator">:</span> <span class="token number">8510700</span><span class="token punctuation">,</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"United States"</span>
<span class="token punctuation">}</span>
<span class="token punctuation">]</span></span>
<span class="token output">1 document in set (0.00 sec)</span></code></pre>
</div>
<p>
In addition, you can alter the returned
documents—adding, renaming, nesting and even computing
new field values—with an expression that describes the
document to return. For example, alter the names of the fields
with the following expression to return only two documents.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa23751052"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">fields</span><span class="token punctuation">(</span>
mysqlx<span class="token punctuation">.</span><span class="token function">expr</span><span class="token punctuation">(</span><span class="token string">'{"Name": upper(Name), "GNPPerCapita": GNP*1000000/demographics.Population}'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span>
<span class="token inlinejson"><span class="token punctuation">{</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"ARUBA"</span><span class="token punctuation">,</span>
<span class="token property">"GNPPerCapita"</span><span class="token operator">:</span> <span class="token number">8038.834951456311</span>
<span class="token punctuation">}</span>
<span class="token punctuation">{</span>
<span class="token property">"Name"</span><span class="token operator">:</span> <span class="token string">"AFGHANISTAN"</span><span class="token punctuation">,</span>
<span class="token property">"GNPPerCapita"</span><span class="token operator">:</span> <span class="token number">263.0281690140845</span>
<span class="token punctuation">}</span></span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="idm46045127106256">
</a>
Limit, Sort, and Skip Results
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127105568">
</a>
<p>
You can apply the
<code class="literal">
limit()
</code>
,
<code class="literal">
sort()
</code>
, and
<code class="literal">
skip()
</code>
methods to manage the number and order of documents returned
by the
<code class="literal">
find()
</code>
method.
</p>
<p>
To specify the number of documents included in a result set,
append the
<code class="literal">
limit()
</code>
method with a value to
the
<code class="literal">
find()
</code>
method. The following query
returns the first five documents in the
<code class="literal">
countryinfo
</code>
collection.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa4303978"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">)</span>
<span class="token operator">...</span> <span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">5 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
To specify an order for the results, append the
<code class="literal">
sort()
</code>
method to the
<code class="literal">
find()
</code>
method. Pass to the
<code class="literal">
sort()
</code>
method a list of one or more fields
to sort by and, optionally, the descending
(
<code class="literal">
desc
</code>
) or ascending
(
<code class="literal">
asc
</code>
) attribute as appropriate. Ascending
order is the default order type.
</p>
<p>
For example, the following query sorts all documents by the
IndepYear field and then returns the first eight documents in
descending order.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa38315623"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token string">"IndepYear desc"</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">8</span><span class="token punctuation">)</span>
<span class="token operator">...</span> <span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">8 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
By default, the
<code class="literal">
limit()
</code>
method starts from
the first document in the collection. You can use the
<code class="literal">
skip()
</code>
method to change the starting
document. For example, to ignore the first document and return
the next eight documents matching the condition, pass to the
<code class="literal">
skip()
</code>
method a value of 1.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa42339326"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-py></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">[</span><span class="token string">"IndepYear desc"</span><span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">8</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">skip</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token operator">...</span> <span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">8 documents in set (0.00 sec)</span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="idm46045127083568">
</a>
Related Information
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="functions.html" title="Chapter 14 Functions and Operators">
MySQL Reference
Manual
</a>
provides detailed documentation on functions
and operators.
</p>
</li>
<li class="listitem">
<p>
See
<a class="ulink" href="/doc/x-devapi-userguide/en/crud-ebnf-collection-crud-functions.html#crud-ebnf-collectionfindfunction" target="_top">
CollectionFindFunction
</a>
for
the full syntax definition.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/information-schema-user-attributes-table.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="information-schema-user-attributes-table">
</a>
28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045078103008">
</a>
<p>
The
<a class="link" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table">
<code class="literal">
USER_ATTRIBUTES
</code>
</a>
table provides
information about user comments and user attributes. It takes its
values from the
<code class="literal">
mysql.user
</code>
system table.
</p>
<p>
The
<a class="link" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table">
<code class="literal">
USER_ATTRIBUTES
</code>
</a>
table has these
columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
USER
</code>
</p>
<p>
The user name portion of the account to which the
<code class="literal">
ATTRIBUTE
</code>
column value applies.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
HOST
</code>
</p>
<p>
The host name portion of the account to which the
<code class="literal">
ATTRIBUTE
</code>
column value applies.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ATTRIBUTE
</code>
</p>
<p>
The user comment, user attribute, or both belonging to the
account specified by the
<code class="literal">
USER
</code>
and
<code class="literal">
HOST
</code>
columns. The value is in JSON object
notation. Attributes are shown exactly as set using
<a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement">
<code class="literal">
CREATE
USER
</code>
</a>
and
<a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement">
<code class="literal">
ALTER
USER
</code>
</a>
statements with
<code class="literal">
ATTRIBUTE
</code>
or
<code class="literal">
COMMENT
</code>
options. A comment is shown as a
key-value pair having
<code class="literal">
comment
</code>
as the key.
For additional information and examples, see
<a class="xref" href="create-user.html#create-user-comments-attributes" title="CREATE USER Comment and Attribute Options">
CREATE USER Comment and Attribute Options
</a>
.
</p>
</li>
</ul>
</div>
<h4>
<a name="idm46045078082496">
</a>
Notes
</h4>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table">
<code class="literal">
USER_ATTRIBUTES
</code>
</a>
is a nonstandard
<code class="literal">
INFORMATION_SCHEMA
</code>
table.
</p>
</li>
<li class="listitem">
<p>
To obtain only the user comment for a given user as an
unquoted string, you can employ a query such as this one:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa60191377"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">ATTRIBUTE</span><span class="token operator">-</span><span class="token operator">>></span><span class="token string">"$.comment"</span> <span class="token keyword">AS</span> <span class="token keyword">Comment</span>
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>USER_ATTRIBUTES
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> <span class="token keyword">USER</span><span class="token operator">=</span><span class="token string">'bill'</span> <span class="token operator">AND</span> <span class="token keyword">HOST</span><span class="token operator">=</span><span class="token string">'localhost'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Comment <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> A comment <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
Similarly, you can obtain the unquoted value for a given user
attribute using its key.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table">
<code class="literal">
USER_ATTRIBUTES
</code>
</a>
contents are
accessible as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
All rows are accessible if:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: square; ">
<li class="listitem">
<p>
The current thread is a replica thread.
</p>
</li>
<li class="listitem">
<p>
The access control system has not been initialized
(for example, the server was started with the
<a class="link" href="server-options.html#option_mysqld_skip-grant-tables">
<code class="option">
--skip-grant-tables
</code>
</a>
option).
</p>
</li>
<li class="listitem">
<p>
The currently authenticated account has the
<a class="link" href="privileges-provided.html#priv_update">
<code class="literal">
UPDATE
</code>
</a>
or
<a class="link" href="privileges-provided.html#priv_select">
<code class="literal">
SELECT
</code>
</a>
privilege for
the
<code class="literal">
mysql.user
</code>
system table.
</p>
</li>
<li class="listitem">
<p>
The currently authenticated account has the
<a class="link" href="privileges-provided.html#priv_create-user">
<code class="literal">
CREATE USER
</code>
</a>
and
<a class="link" href="privileges-provided.html#priv_system-user">
<code class="literal">
SYSTEM_USER
</code>
</a>
privileges.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Otherwise, the currently authenticated account can see the
row for that account. Additionally, if the account has the
<a class="link" href="privileges-provided.html#priv_create-user">
<code class="literal">
CREATE USER
</code>
</a>
privilege but
not the
<a class="link" href="privileges-provided.html#priv_system-user">
<code class="literal">
SYSTEM_USER
</code>
</a>
privilege, it can see rows for all other accounts that do
not have the
<a class="link" href="privileges-provided.html#priv_system-user">
<code class="literal">
SYSTEM_USER
</code>
</a>
privilege.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
For more information about specifying account comments and
attributes, see
<a class="xref" href="create-user.html" title="15.7.1.3 CREATE USER Statement">
Section 15.7.1.3, “CREATE USER Statement”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-configurator-workflow-server.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-configurator-workflow-server">
</a>
2.3.2.1 MySQL Server Configuration with MySQL Configurator
</h4>
</div>
</div>
</div>
<p>
MySQL Configurator performs the initial configuration, a reconfiguration,
and also functions as part of the uninstallation process.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Full permissions are granted to the user executing MySQL Configurator to
all generated files, such as
<code class="filename">
my.ini
</code>
. This
does not apply to files and directories for specific products,
such as the MySQL server data directory in
<code class="literal">
%ProgramData%
</code>
that is owned by
<code class="literal">
SYSTEM
</code>
.
</p>
</div>
<p>
MySQL Configurator performs the configuration of the MySQL server. For
example:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
It creates the configuration file
(
<code class="filename">
my.ini
</code>
) that is used to configure the
MySQL server. The values written to this file are influenced
by choices you make during the installation process. Some
definitions are host dependent.
</p>
</li>
<li class="listitem">
<p>
By default, a Windows service for the MySQL server is added.
</p>
</li>
<li class="listitem">
<p>
Provides default installation and data paths for MySQL server.
</p>
</li>
<li class="listitem">
<p>
It can optionally create MySQL server user accounts with
configurable permissions based on general roles, such as DB
Administrator, DB Designer, and Backup Admin.
</p>
</li>
<li class="listitem">
<p>
Checking
<span class="guilabel">
Show Advanced Options
</span>
enables
additional
<span class="guilabel">
Logging Options
</span>
to be set.
This includes defining custom file paths for the error log,
general log, slow query log (including the configuration of
seconds it requires to execute a query), and the binary log.
</p>
</li>
</ul>
</div>
<p>
The sections that follow describe the server configuration options
that apply to MySQL server on Windows. The server version you
installed will determine which steps and options you can
configure. Configuring MySQL server may include some or all of the
steps.
</p>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-existing-installations">
</a>
2.3.2.1.1 MySQL Server Installations
</h5>
</div>
</div>
</div>
<p>
MySQL Configurator adds an upgrade option if it finds an existing MySQL
Server installation is discovered. It offers two options:
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
This upgrade functionality was added in MySQL 8.3.0.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h6 class="title">
<a name="server-existing-installations-replace">
</a>
In-Place Upgrade of an Existing MySQL Server Installation
</h6>
</div>
</div>
</div>
<p>
This replaces the existing MySQL server installation as part
of the upgrade process which may also upgrade the data schema.
Upon success, the existing MySQL server installation is
removed from the system.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The existing MySQL server instance must be running for the
in-place upgrade option to function.
</p>
</div>
<p>
While MySQL Configurator may attempt (and succeed) to perform an
in-place upgrade for other scenarios, the following table
lists the scenarios officially supported by the configurator:
</p>
<div class="table">
<a name="idm46045332346048">
</a>
<p class="title">
<b>
Table 2.5 Supported Upgrade Paths
</b>
</p>
<div class="table-contents">
<table summary="Upgrade paths officially supported by MySQL Configurator">
<colgroup>
<col style="width: 25%"/>
<col style="width: 75%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
A supported upgrade scenario
</th>
<th scope="col">
Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td scope="row">
8.0.35+ to 8.1
</td>
<td>
From 8.0.35 or higher to the first MySQL 8 Innovation release.
</td>
</tr>
<tr>
<td scope="row">
8.0.35+ to 8.4
</td>
<td>
From 8.0.35 or higher to the MySQL next LTS release.
</td>
</tr>
<tr>
<td scope="row">
8.X to 8.Y where Y = X + 1
</td>
<td>
From an Innovation release to the next consecutive Innovation release.
</td>
</tr>
<tr>
<td scope="row">
8.3 to 8.4
</td>
<td>
From the last MySQL 8 Innovation release to the next MySQL 8 LTS
release.
</td>
</tr>
<tr>
<td scope="row">
8.4.X to 8.4.Y where Y > X
</td>
<td>
From within the same LTS release.
</td>
</tr>
<tr>
<td scope="row">
8.4.X to 9.0.0
</td>
<td>
From an LTS release to the first consecutive Innovation release.
</td>
</tr>
<tr>
<td scope="row">
8.4 to 9.7
</td>
<td>
From an LTS release to the next consecutive LTS release.
</td>
</tr>
</tbody>
</table>
</div>
</div>
<br class="table-break"/>
<p>
This dialogue prompts for the protocol (default: TCP/IP), port
(default: 3306), and root password for the existing
installation. Execute connect and then review and confirm the
MySQL instance's information (such as version, paths, and
configuration file) before proceeding with the upgrade.
</p>
<p>
This upgrade may replace the file paths. For example, "MySQL
Server 8.2\Data\" changes to "MySQL Server 8.3\Data\" when
upgrading 8.2 to 8.3.
</p>
<p>
This upgrade functionality also provides these additional
options: "Backup Data" allows running
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
before performing the upgrade,
and "Server File Permissions" to optionally customize file
permissions.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h6 class="title">
<a name="server-existing-installations-add">
</a>
Add a Separate MySQL Server Installation
</h6>
</div>
</div>
</div>
<p>
Configure a standard side-by-side installation with the new
MySQL server installation. This means having multiple MySQL
server installations installed and running on the system.
</p>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-type-network">
</a>
2.3.2.1.2 Type and Networking
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Server Configuration Type
</p>
<p>
Choose the MySQL server configuration type that describes
your setup. This setting defines the amount of system
resources (memory) to assign to your MySQL server instance.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<span class="bold">
<strong>
Development
</strong>
</span>
: A computer
that hosts many other applications, and typically this
is your personal workstation. This setting configures
MySQL to use the least amount of memory.
</p>
</li>
<li class="listitem">
<p>
<span class="bold">
<strong>
Server
</strong>
</span>
: Several other
applications are expected to run on this computer, such
as a web server. The Server setting configures MySQL to
use a medium amount of memory.
</p>
</li>
<li class="listitem">
<p>
<span class="bold">
<strong>
Dedicated
</strong>
</span>
: A computer
that is dedicated to running the MySQL server. Because
no other major applications run on this server, this
setting configures MySQL to use the majority of
available memory.
</p>
</li>
<li class="listitem">
<p>
</p>
<p>
<span class="bold">
<strong>
Manual
</strong>
</span>
: Prevents
MySQL Configurator from attempting to optimize the server
installation, and instead, sets the default values to
the server variables included in the
<code class="filename">
my.ini
</code>
configuration file. With the
<code class="literal">
Manual
</code>
type selected, MySQL Configurator uses
the default value of 16M for the
<a class="link" href="server-system-variables.html#sysvar_tmp_table_size">
<code class="literal">
tmp_table_size
</code>
</a>
variable
assignment.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Connectivity
</p>
<p>
Connectivity options control how the connection to MySQL is
made. Options include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<span class="guilabel">
TCP/IP
</span>
: This option is selected by
default. You may disable TCP/IP Networking to permit
local host connections only. With the TCP/IP connection
option selected, you can modify the following items:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: square; ">
<li class="listitem">
<p>
<span class="guilabel">
Port
</span>
for classic MySQL protocol
connections. The default value is
<code class="literal">
3306
</code>
.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
X Protocol Port
</span>
defaults to
<code class="literal">
33060
</code>
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Open Windows Firewall port for network
access
</span>
, which is selected by default for
TCP/IP connections.
</p>
</li>
</ul>
</div>
<p>
If a port number is in use already, you will see the
error icon (
<span class="inlinemediaobject">
<img align="middle" height="20" src="images/mi-info-symbol.png" width="22"/>
</span>
) next to the default value and
<span class="guibutton">
Next
</span>
is disabled until you
provide a new port number.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Named Pipe
</span>
: Enable and define the
pipe name, similar to setting the
<a class="link" href="server-system-variables.html#sysvar_named_pipe">
<code class="literal">
named_pipe
</code>
</a>
system
variable. The default name is
<code class="literal">
MySQL
</code>
.
</p>
<p>
When you select
<span class="guilabel">
Named Pipe
</span>
connectivity, and then proceed to the next step, you are
prompted to set the level of access control granted to
client software on named-pipe connections. Some clients
require only minimum access control for communication,
while other clients require full access to the named
pipe.
</p>
<p>
You can set the level of access control based on the
Windows user (or users) running the client as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: square; ">
<li class="listitem">
<p>
<b>
Minimum access to all users (RECOMMENDED).
</b>
This level is enabled by default because it is the
most secure.
</p>
</li>
<li class="listitem">
<p>
<b>
Full access to members of a local group.
</b>
If the minimum-access option is too restrictive
for the client software, use this option to reduce
the number of users who have full access on the
named pipe. The group must be established on
Windows before you can select it from the list.
Membership in this group should be limited and
managed. Windows requires a newly added member to
first log out and then log in again to join a
local group.
</p>
</li>
<li class="listitem">
<p>
<b>
Full access to all users (NOT RECOMMENDED).
</b>
This option is less secure and should be set only
when other safeguards are implemented.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Shared Memory
</span>
: Enable and define
the memory name, similar to setting the
<a class="link" href="server-system-variables.html#sysvar_shared_memory">
<code class="literal">
shared_memory
</code>
</a>
system
variable. The default name is
<code class="literal">
MySQL
</code>
.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Advanced Configuration
</p>
<p>
Check
<span class="guilabel">
Show Advanced and Logging Options
</span>
to set custom logging and advanced options in later steps.
The Logging Options step enables you to define custom file
paths for the error log, general log, slow query log
(including the configuration of seconds it requires to
execute a query), and the binary log. The Advanced Options
step enables you to set the unique server ID required when
binary logging is enabled in a replication topology.
</p>
</li>
<li class="listitem">
<p>
MySQL Enterprise Firewall (Enterprise Edition only)
</p>
<p>
The
<span class="guilabel">
Enable MySQL Enterprise Firewall
</span>
check box is deselected by default. Select this option to
enable a security list that offers protection against
certain types of attacks. Additional post-installation
configuration is required (see
<a class="xref" href="firewall.html" title="8.4.7 MySQL Enterprise Firewall">
Section 8.4.7, “MySQL Enterprise Firewall”
</a>
).
</p>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-accounts-roles">
</a>
2.3.2.1.3 Accounts and Roles
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Root Account Password
</p>
<p>
Assigning a root password is required and you will be asked
for it when reconfiguring with MySQL Configurator in the future.
Password strength is evaluated when you repeat the password
in the box provided. For descriptive information regarding
password requirements or status, move your mouse pointer
over the information icon (
<span class="inlinemediaobject">
<img align="middle" height="20" src="images/mi-info-symbol.png" width="22"/>
</span>
) when it appears.
</p>
</li>
<li class="listitem">
<p>
MySQL User Accounts (Optional)
</p>
<p>
Click
<span class="guibutton">
Add User
</span>
or
<span class="guibutton">
Edit
User
</span>
to create or modify MySQL user accounts
with predefined roles. Next, enter the required account
credentials:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<span class="guilabel">
User Name:
</span>
MySQL user names can be
up to 32 characters long.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Host:
</span>
Select
<code class="literal">
localhost
</code>
for local connections only
or
<code class="literal">
<All Hosts (%)>
</code>
when remote
connections to the server are required.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Role:
</span>
Each predefined role, such as
<code class="literal">
DB Admin
</code>
, is configured with its own
set of privileges. For example, the
<code class="literal">
DB
Admin
</code>
role has more privileges than the
<code class="literal">
DB Designer
</code>
role. The
<span class="guilabel">
Role
</span>
drop-down list contains a
description of each role.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Password:
</span>
Password strength
assessment is performed while you type the password.
Passwords must be confirmed. MySQL permits a blank or
empty password (considered to be insecure).
</p>
</li>
</ul>
</div>
<p>
<b>
MySQL Configurator Commercial Release Only:
</b>
MySQL Enterprise Edition for Windows, a commercial product, also supports an
authentication method that performs external
authentication on Windows. Accounts authenticated by the
Windows operating system can access the MySQL server
without providing an additional password.
</p>
<p>
To create a new MySQL account that uses Windows
authentication, enter the user name and then select a value
for
<span class="guilabel">
Host
</span>
and
<span class="guilabel">
Role
</span>
.
Click
<span class="guilabel">
Windows
</span>
authentication to enable
the
<code class="literal">
authentication_windows
</code>
plugin. In the
Windows Security Tokens area, enter a token for each Windows
user (or group) who can authenticate with the MySQL user
name. MySQL accounts can include security tokens for both
local Windows users and Windows users that belong to a
domain. Multiple security tokens are separated by the
semicolon character (
<code class="literal">
;
</code>
) and use the
following format for local and domain accounts:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Local account
</p>
<p>
Enter the simple Windows user name as the security token
for each local user or group; for example,
<strong class="userinput">
<code>
finley;jeffrey;admin
</code>
</strong>
.
</p>
</li>
<li class="listitem">
<p>
Domain account
</p>
<p>
Use standard Windows syntax
(
<em class="replaceable">
<code>
domain
</code>
</em>
<code class="literal">
\
</code>
<em class="replaceable">
<code>
domainuser
</code>
</em>
)
or MySQL syntax
(
<em class="replaceable">
<code>
domain
</code>
</em>
<code class="literal">
\\
</code>
<em class="replaceable">
<code>
domainuser
</code>
</em>
)
to enter Windows domain users and groups.
</p>
<p>
For domain accounts, you may need to use the credentials
of an administrator within the domain if the account
running MySQL Configurator lacks the permissions to query the
Active Directory. If this is the case, select
<span class="guilabel">
Validate Active Directory users
with
</span>
to activate the domain administrator
credentials.
</p>
</li>
</ul>
</div>
<p>
Windows authentication permits you to test all of the
security tokens each time you add or modify a token. Click
<span class="guibutton">
Test Security Tokens
</span>
to validate (or
revalidate) each token. Invalid tokens generate a
descriptive error message along with a red
<code class="literal">
X
</code>
icon and red token text. When all
tokens resolve as valid (green text without an
<code class="literal">
X
</code>
icon), you can click
<span class="guibutton">
OK
</span>
to save the changes.
</p>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-windows-service">
</a>
2.3.2.1.4 Windows Service
</h5>
</div>
</div>
</div>
<p>
On the Windows platform, MySQL server can run as a named service
managed by the operating system and be configured to start up
automatically when Windows starts. Alternatively, you can
configure MySQL server to run as an executable program that
requires manual configuration.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="guilabel">
Configure MySQL server as a Windows
service
</span>
(Selected by default.)
</p>
<p>
When the default configuration option is selected, you can
also select the following:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<span class="guilabel">
Windows Service Name
</span>
</p>
<p>
Defaults to MySQL
<em class="replaceable">
<code>
XY
</code>
</em>
where XY
is 81 for MySQL 8.1.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Start the MySQL Server at System
Startup
</span>
</p>
<p>
When selected (default), the service startup type is set
to Automatic; otherwise, the startup type is set to
Manual.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Run Windows Service as
</span>
</p>
<p>
When
<span class="guilabel">
Standard System Account
</span>
is
selected (default), the service logs on as Network
Service.
</p>
<p>
The
<span class="guilabel">
Custom User
</span>
option must have
privileges to log on to Microsoft Windows as a service.
The
<span class="guibutton">
Next
</span>
button will be disabled
until this user is configured with the required
privileges.
</p>
<p>
A custom user account is configured in Windows by
searching for "local security policy" in the Start menu.
In the Local Security Policy window, select
<span class="guilabel">
Local Policies
</span>
,
<span class="guilabel">
User
Rights Assignment
</span>
, and then
<span class="guilabel">
Log On
As A Service
</span>
to open the property dialog.
Click
<span class="guibutton">
Add User or Group
</span>
to add
the custom user and then click
<span class="guibutton">
OK
</span>
in each dialog to save the changes.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-file-permission-options">
</a>
2.3.2.1.5 Server File Permissions
</h5>
</div>
</div>
</div>
<p>
Optionally, permissions set on the folders and files located at
<code class="filename">
C:\ProgramData\MySQL\MySQL Server
<em class="replaceable">
<code>
X.Y
</code>
</em>
\Data
</code>
can be managed
during the server configuration operation. You have the
following options:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
MySQL Configurator can configure the folders and files with full
control granted exclusively to the user running the Windows
service, if applicable, and to the Administrators group.
</p>
<p>
All other groups and users are denied access. This is the
default option.
</p>
</li>
<li class="listitem">
<p>
Have MySQL Configurator use a configuration option similar to the one
just described, but also have MySQL Configurator show which users
could have full control.
</p>
<p>
You are then able to decide if a group or user should be
given full control. If not, you can move the qualified
members from this list to a second list that restricts all
access.
</p>
</li>
<li class="listitem">
<p>
Have MySQL Configurator skip making file-permission changes during
the configuration operation.
</p>
<p>
If you select this option, you are responsible for securing
the
<code class="filename">
Data
</code>
folder and its related files
manually after the server configuration finishes.
</p>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-logging-options">
</a>
2.3.2.1.6 Logging Options
</h5>
</div>
</div>
</div>
<p>
This step is available if the
<span class="guilabel">
Show Advanced
Configuration
</span>
check box was selected during the
<span class="guilabel">
Type and Networking
</span>
step. To enable this
step now, click
<span class="guibutton">
Back
</span>
to return to the
<span class="guilabel">
Type and Networking
</span>
step and select the
check box.
</p>
<p>
Advanced configuration options are related to the following
MySQL log files:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="error-log.html" title="7.4.2 The Error Log">
Error Log
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="query-log.html" title="7.4.3 The General Query Log">
General Log
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="slow-query-log.html" title="7.4.5 The Slow Query Log">
Slow Query Log
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="binary-log.html" title="7.4.4 The Binary Log">
Binary Log
</a>
</p>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-advanced-options">
</a>
2.3.2.1.7 Advanced Options
</h5>
</div>
</div>
</div>
<p>
This step is available if the
<span class="guilabel">
Show Advanced
Configuration
</span>
check box was selected during the
<span class="guilabel">
Type and Networking
</span>
step. To enable this
step now, click
<span class="guibutton">
Back
</span>
to return to the
<span class="guilabel">
Type and Networking
</span>
step and select the
check box.
</p>
<p>
The advanced-configuration options include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="guilabel">
Server ID
</span>
</p>
<p>
Set the unique identifier used in a replication topology. If
binary logging is enabled, you must specify a server ID. The
default ID value depends on the server version. For more
information, see the description of the
<a class="link" href="replication-options.html#sysvar_server_id">
<code class="literal">
server_id
</code>
</a>
system variable.
</p>
</li>
<li class="listitem">
<p>
<span class="guilabel">
Table Names Case
</span>
</p>
<p>
These options only apply to the initial configuration of the
MySQL server.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Lower Case
</p>
<p>
Sets the
<a class="link" href="server-system-variables.html#sysvar_lower_case_table_names">
<code class="literal">
lower_case_table_names
</code>
</a>
option value to 1 (default), in which table names are
stored in lowercase on disk and comparisons are not
case-sensitive.
</p>
</li>
<li class="listitem">
<p>
Preserve Given Case
</p>
<p>
Sets the
<a class="link" href="server-system-variables.html#sysvar_lower_case_table_names">
<code class="literal">
lower_case_table_names
</code>
</a>
option value to 2, in which table names are stored as
given but compared in lowercase.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-sample-databases">
</a>
2.3.2.1.8 Sample Databases
</h5>
</div>
</div>
</div>
<p>
Optionally install sample databases that include test data to
help develop applications with MySQL. The options include the
<a class="ulink" href="/doc/sakila/en/" target="_top">
sakila
</a>
and
<a class="ulink" href="/doc/world-setup/en/" target="_top">
world
</a>
databases.
</p>
</div>
<div class="section">
<div class="titlepage">
<div>
<div>
<h5 class="title">
<a name="server-apply-config">
</a>
2.3.2.1.9 Apply Configuration
</h5>
</div>
</div>
</div>
<p>
All configuration settings are applied to the MySQL server when
you click
<span class="guibutton">
Execute
</span>
. Use the
<span class="guilabel">
Configuration Steps
</span>
tab to follow the
progress of each action; the icon for each toggles from white to
green (with a check mark) on success. Otherwise, the process
stops and displays an error message if an individual action
times out. Click the
<span class="guilabel">
Log
</span>
tab to view the
log.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/upgrading-what-is-upgraded.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="upgrading-what-is-upgraded">
</a>
3.4 What the MySQL Upgrade Process Upgrades
</h2>
</div>
</div>
</div>
<p>
Installing a new version of MySQL may require upgrading these
parts of the existing installation:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<code class="literal">
mysql
</code>
system schema, which contains
tables that store information required by the MySQL server as
it runs (see
<a class="xref" href="system-schema.html" title="7.3 The mysql System Schema">
Section 7.3, “The mysql System Schema”
</a>
).
<code class="literal">
mysql
</code>
schema tables fall into two broad
categories:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Data dictionary tables, which store database object
metadata.
</p>
</li>
<li class="listitem">
<p>
System tables (that is, the remaining non-data dictionary
tables), which are used for other operational purposes.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Other schemas, some of which are built in and may be
considered
<span class="quote">
“
<span class="quote">
owned
</span>
”
</span>
by the server, and others
which are not:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The
<a class="link" href="performance-schema.html" title="Chapter 29 MySQL Performance Schema">
<code class="literal">
performance_schema
</code>
</a>
,
<a class="link" href="information-schema.html" title="Chapter 28 INFORMATION_SCHEMA Tables">
<code class="literal">
INFORMATION_SCHEMA
</code>
</a>
,
<a class="link" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database">
<code class="literal">
ndbinfo
</code>
</a>
, and
<a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema">
<code class="literal">
sys
</code>
</a>
schemas.
</p>
</li>
<li class="listitem">
<p>
User schemas.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
Two distinct version numbers are associated with parts of the
installation that may require upgrading:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The data dictionary version. This applies to the data
dictionary tables.
</p>
</li>
<li class="listitem">
<p>
The server version, also known as the MySQL version. This
applies to the system tables and objects in other schemas.
</p>
</li>
</ul>
</div>
<p>
In both cases, the actual version applicable to the existing MySQL
installation is stored in the data dictionary, and the current
expected version is compiled into the new version of MySQL. When
an actual version is lower than the current expected version,
those parts of the installation associated with that version must
be upgraded to the current version. If both versions indicate an
upgrade is needed, the data dictionary upgrade must occur first.
</p>
<p>
As a reflection of the two distinct versions just mentioned, the
upgrade occurs in two steps:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Step 1: Data dictionary upgrade.
</p>
<p>
This step upgrades:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The data dictionary tables in the
<code class="literal">
mysql
</code>
schema. If the actual data dictionary version is lower
than the current expected version, the server creates data
dictionary tables with updated definitions, copies
persisted metadata to the new tables, atomically replaces
the old tables with the new ones, and reinitializes the
data dictionary.
</p>
</li>
<li class="listitem">
<p>
The Performance Schema,
<code class="literal">
INFORMATION_SCHEMA
</code>
, and
<code class="literal">
ndbinfo
</code>
.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Step 2: Server upgrade.
</p>
<p>
This step comprises all other upgrade tasks. If the server
version of the existing MySQL installation is lower than that
of the new installed MySQL version, everything else must be
upgraded:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The system tables in the
<code class="literal">
mysql
</code>
schema
(the remaining non-data dictionary tables).
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
sys
</code>
schema.
</p>
</li>
<li class="listitem">
<p>
User schemas.
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
The data dictionary upgrade (step 1) is the responsibility of the
server, which performs this task as necessary at startup unless
invoked with an option that prevents it from doing so. The option
is
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade=NONE
</code>
</a>
.
</p>
<p>
If the data dictionary is out of date but the server is prevented
from upgrading it, the server does not run, and exits with an
error instead. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa38838395"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[ERROR] [MY-013381] [Server] Server shutting down because upgrade is
required, yet prohibited by the command line option '--upgrade=NONE'.
[ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine
[ERROR] [MY-010020] [Server] Data Dictionary initialization failed.</code></pre>
</div>
<p>
The
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade
</code>
</a>
server option
controls whether and how the server performs an automatic upgrade
at startup:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
With no option or with
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade=AUTO
</code>
</a>
, the server
upgrades anything it determines to be out of date (steps 1 and
2).
</p>
</li>
<li class="listitem">
<p>
With
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade=NONE
</code>
</a>
, the server
upgrades nothing (skips steps 1 and 2), but also exits with an
error if the data dictionary must be upgraded. It is not
possible to run the server with an out-of-date data
dictionary; the server insists on either upgrading it or
exiting.
</p>
</li>
<li class="listitem">
<p>
With
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade=MINIMAL
</code>
</a>
, the
server upgrades the data dictionary, the Performance Schema,
and the
<code class="literal">
INFORMATION_SCHEMA
</code>
, if necessary
(step 1). Note that following an upgrade with this option,
Group Replication cannot be started, because system tables on
which the replication internals depend are not updated, and
reduced functionality might also be apparent in other areas.
</p>
</li>
<li class="listitem">
<p>
With
<a class="link" href="server-options.html#option_mysqld_upgrade">
<code class="option">
--upgrade=FORCE
</code>
</a>
, the
server upgrades the data dictionary, the Performance Schema,
and the
<code class="literal">
INFORMATION_SCHEMA
</code>
, if necessary
(step 1), and forces an upgrade of everything else (step 2).
Expect server startup to take longer with this option because
the server checks all objects in all schemas.
</p>
</li>
</ul>
</div>
<p>
<code class="literal">
FORCE
</code>
is useful to force step 2 actions to be
performed if the server thinks they are not necessary. One way
that
<code class="literal">
FORCE
</code>
differs from
<code class="literal">
AUTO
</code>
is that with
<code class="literal">
FORCE
</code>
, the server re-creates
system tables such as help tables or time zone tables if they are
missing.
</p>
<p>
Additional notes about what occurs during upgrade step 2:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Step 2 installs the
<code class="literal">
sys
</code>
schema if it is not
installed, and upgrades it to the current version otherwise.
An error occurs if a
<code class="literal">
sys
</code>
schema exists but
has no
<code class="literal">
version
</code>
view, on the assumption that
its absence indicates a user-created schema:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa86592220"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">A sys schema exists with no sys.version view. If
you have a user created sys schema, this must be renamed for the
upgrade to succeed.</code></pre>
</div>
<p>
To upgrade in this case, remove or rename the existing
<code class="literal">
sys
</code>
schema first. Then perform the upgrade
procedure again. (It may be necessary to force step 2.)
</p>
<p>
To prevent the
<code class="literal">
sys
</code>
schema check, start the
server with the
<code class="option">
--upgrade=NONE
</code>
or
<code class="option">
--upgrade=MINIMAL
</code>
option.
</p>
</li>
<li class="listitem">
<p>
Step 2 upgrades the system tables to ensure that they have the
current structure, and this includes the help tables but not
the time zone tables. The procedure for loading time zone
tables is platform dependent and requires decision making by
the DBA, so it cannot be done automatically.
</p>
</li>
<li class="listitem">
<p>
When Step 2 is upgrading the system tables in the
<code class="literal">
mysql
</code>
schema, the column order in the
primary key of the
<code class="literal">
mysql.db
</code>
,
<code class="literal">
mysql.tables_priv
</code>
,
<code class="literal">
mysql.columns_priv
</code>
and
<code class="literal">
mysql.procs_priv
</code>
tables is changed to place
the host name and user name columns together. Placing the host
name and user name together means that index lookup can be
used, which improves performance for
<a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement">
<code class="literal">
CREATE USER
</code>
</a>
,
<a class="link" href="drop-user.html" title="15.7.1.5 DROP USER Statement">
<code class="literal">
DROP USER
</code>
</a>
, and
<a class="link" href="rename-user.html" title="15.7.1.7 RENAME USER Statement">
<code class="literal">
RENAME USER
</code>
</a>
statements, and for
ACL checks for multiple users with multiple privileges.
Dropping and re-creating the index is necessary and might take
some time if the system has a large number of users and
privileges.
</p>
</li>
<li class="listitem">
<p>
Step 2 processes all tables in all user schemas as necessary.
Table checking might take a long time to complete. Each table
is locked and therefore unavailable to other sessions while it
is being processed. Check and repair operations can be
time-consuming, particularly for large tables. Table checking
uses the
<code class="literal">
FOR UPGRADE
</code>
option of the
<a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement">
<code class="literal">
CHECK TABLE
</code>
</a>
statement. For
details about what this option entails, see
<a class="xref" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement">
Section 15.7.3.2, “CHECK TABLE Statement”
</a>
.
</p>
<p>
To prevent table checking, start the server with the
<code class="option">
--upgrade=NONE
</code>
or
<code class="option">
--upgrade=MINIMAL
</code>
option.
</p>
<p>
To force table checking, start the server with the
<code class="option">
--upgrade=FORCE
</code>
option.
</p>
</li>
<li class="listitem">
<p>
Step 2 marks all checked and repaired tables with the current
MySQL version number. This ensures that the next time upgrade
checking occurs with the same version of the server, it can be
determined whether there is any need to check or repair a
given table again.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-ft-default-stopword-table.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="information-schema-innodb-ft-default-stopword-table">
</a>
28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045076884160">
</a>
<p>
The
<a class="link" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table">
<code class="literal">
INNODB_FT_DEFAULT_STOPWORD
</code>
</a>
table
holds a list of
<a class="link" href="glossary.html#glos_stopword" title="stopword">
stopwords
</a>
that are used by default when creating a
<code class="literal">
FULLTEXT
</code>
index on
<code class="literal">
InnoDB
</code>
tables. For information about the default
<code class="literal">
InnoDB
</code>
stopword list and how to define your own
stopword lists, see
<a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords">
Section 14.9.4, “Full-Text Stopwords”
</a>
.
</p>
<p>
For related usage information and examples, see
<a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables">
Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables”
</a>
.
</p>
<p>
The
<a class="link" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table">
<code class="literal">
INNODB_FT_DEFAULT_STOPWORD
</code>
</a>
table
has these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
value
</code>
</p>
<p>
A word that is used by default as a stopword for
<code class="literal">
FULLTEXT
</code>
indexes on
<code class="literal">
InnoDB
</code>
tables. This is not used if you
override the default stopword processing with either the
<a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table">
<code class="literal">
innodb_ft_server_stopword_table
</code>
</a>
or the
<a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table">
<code class="literal">
innodb_ft_user_stopword_table
</code>
</a>
system variable.
</p>
</li>
</ul>
</div>
<h4>
<a name="idm46045076867680">
</a>
Example
</h4>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa30159755"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_FT_DEFAULT_STOPWORD<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> value <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> about <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> an <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> are <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> as <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> at <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> be <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> by <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> com <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> de <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> en <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> for <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> from <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> how <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> i <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> in <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> is <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> it <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> la <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> of <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> on <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> or <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> that <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> the <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> this <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> to <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> was <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> what <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> when <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> where <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> who <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> will <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> with <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> und <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> the <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> www <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">36 rows in set (0.00 sec)</span></code></pre>
</div>
<h4>
<a name="idm46045076864880">
</a>
Notes
</h4>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
You must have the
<a class="link" href="privileges-provided.html#priv_process">
<code class="literal">
PROCESS
</code>
</a>
privilege to query this table.
</p>
</li>
<li class="listitem">
<p>
Use the
<code class="literal">
INFORMATION_SCHEMA
</code>
<a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table">
<code class="literal">
COLUMNS
</code>
</a>
table or the
<a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement">
<code class="literal">
SHOW COLUMNS
</code>
</a>
statement to view
additional information about the columns of this table,
including data types and default values.
</p>
</li>
<li class="listitem">
<p>
For more information about
<code class="literal">
InnoDB
</code>
<code class="literal">
FULLTEXT
</code>
search, see
<a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes">
Section 17.6.2.4, “InnoDB Full-Text Indexes”
</a>
, and
<a class="xref" href="fulltext-search.html" title="14.9 Full-Text Search Functions">
Section 14.9, “Full-Text Search Functions”
</a>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/program-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="program-options">
</a>
6.2.2 Specifying Program Options
</h3>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="command-line-options.html">
6.2.2.1 Using Options on the Command Line
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="option-files.html">
6.2.2.2 Using Option Files
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="option-file-options.html">
6.2.2.3 Command-Line Options that Affect Option-File Handling
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="option-modifiers.html">
6.2.2.4 Program Option Modifiers
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="program-variables.html">
6.2.2.5 Using Options to Set Program Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="option-defaults-equals.html">
6.2.2.6 Option Defaults, Options Expecting Values, and the = Sign
</a>
</span>
</dt>
</dl>
</div>
<p>
There are several ways to specify options for MySQL programs:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
List the options on the command line following the program
name. This is common for options that apply to a specific
invocation of the program.
</p>
</li>
<li class="listitem">
<p>
List the options in an option file that the program reads when
it starts. This is common for options that you want the
program to use each time it runs.
</p>
</li>
<li class="listitem">
<p>
List the options in environment variables (see
<a class="xref" href="setting-environment-variables.html" title="6.2.9 Setting Environment Variables">
Section 6.2.9, “Setting Environment Variables”
</a>
). This method
is useful for options that you want to apply each time the
program runs. In practice, option files are used more commonly
for this purpose, but
<a class="xref" href="multiple-unix-servers.html" title="7.8.3 Running Multiple MySQL Instances on Unix">
Section 7.8.3, “Running Multiple MySQL Instances on Unix”
</a>
,
discusses one situation in which environment variables can be
very helpful. It describes a handy technique that uses such
variables to specify the TCP/IP port number and Unix socket
file for the server and for client programs.
</p>
</li>
</ul>
</div>
<p>
Options are processed in order, so if an option is specified
multiple times, the last occurrence takes precedence. The
following command causes
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
to connect to
the server running on
<code class="literal">
localhost
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa58488372"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">-h</span> example<span class="token punctuation">.</span>com <span class="token property">-h</span> localhost</code></pre>
</div>
<p>
There is one exception: For
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
, the
<span class="emphasis">
<em>
first
</em>
</span>
instance of the
<a class="link" href="server-options.html#option_mysqld_user">
<code class="option">
--user
</code>
</a>
option is used as a security
precaution, to prevent a user specified in an option file from
being overridden on the command line.
</p>
<p>
If conflicting or related options are given, later options take
precedence over earlier options. The following command runs
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
in
<span class="quote">
“
<span class="quote">
no column names
</span>
”
</span>
mode:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa75701261"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">--column-names</span> <span class="token property">--skip-column-names</span></code></pre>
</div>
<a class="indexterm" name="idm46045324240928">
</a>
<a class="indexterm" name="idm46045324239440">
</a>
<p>
MySQL programs determine which options are given first by
examining environment variables, then by processing option files,
and then by checking the command line. Because later options take
precedence over earlier ones, the processing order means that
environment variables have the lowest precedence and command-line
options the highest.
</p>
<a class="indexterm" name="idm46045324237568">
</a>
<a class="indexterm" name="idm46045324236480">
</a>
<p>
For the server, one exception applies: The
<span class="command">
<strong>
mysqld-auto.cnf
</strong>
</span>
option file in the data
directory is processed last, so it takes precedence even over
command-line options.
</p>
<p>
You can take advantage of the way that MySQL programs process
options by specifying default option values for a program in an
option file. That enables you to avoid typing them each time you
run the program while enabling you to override the defaults if
necessary by using command-line options.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-rules-db-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="replication-rules-db-options">
</a>
19.2.5.1 Evaluation of Database-Level Replication and Binary Logging Options
</h4>
</div>
</div>
</div>
<p>
When evaluating replication options, the replica begins by
checking to see whether there are any
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-do-db">
<code class="option">
--replicate-do-db
</code>
</a>
or
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-ignore-db">
<code class="option">
--replicate-ignore-db
</code>
</a>
options
that apply. When using
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-do-db">
<code class="option">
--binlog-do-db
</code>
</a>
or
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-ignore-db">
<code class="option">
--binlog-ignore-db
</code>
</a>
, the process
is similar, but the options are checked on the source.
</p>
<p>
The database that is checked for a match depends on the binary
log format of the statement that is being handled. If the
statement has been logged using the row format, the database
where data is to be changed is the database that is checked. If
the statement has been logged using the statement format, the
default database (specified with a
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
</code>
</a>
statement) is the database
that is checked.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Only DML statements can be logged using the row format. DDL
statements are always logged as statements, even when
<a class="link" href="replication-options-binary-log.html#sysvar_binlog_format">
<code class="literal">
binlog_format=ROW
</code>
</a>
. All DDL
statements are therefore always filtered according to the
rules for statement-based replication. This means that you
must select the default database explicitly with a
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
</code>
</a>
statement in order for a
DDL statement to be applied.
</p>
</div>
<p>
For replication, the steps involved are listed here:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
Which logging format is used?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
STATEMENT.
</b>
Test the default database.
</p>
</li>
<li class="listitem">
<p>
<b>
ROW.
</b>
Test the database affected by the changes.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Are there any
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-do-db">
<code class="option">
--replicate-do-db
</code>
</a>
options?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Does the database match any of them?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Continue to Step 4.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Ignore the update and exit.
</p>
</li>
</ul>
</div>
<p>
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Continue to step 3.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Are there any
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-ignore-db">
<code class="option">
--replicate-ignore-db
</code>
</a>
options?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Does the database match any of them?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Ignore the update and exit.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Continue to step 4.
</p>
</li>
</ul>
</div>
<p>
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Continue to step 4.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Proceed to checking the table-level replication options, if
there are any. For a description of how these options are
checked, see
<a class="xref" href="replication-rules-table-options.html" title="19.2.5.2 Evaluation of Table-Level Replication Options">
Section 19.2.5.2, “Evaluation of Table-Level Replication Options”
</a>
.
</p>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
A statement that is still permitted at this stage is not
yet actually executed. The statement is not executed until
all table-level options (if any) have also been checked,
and the outcome of that process permits execution of the
statement.
</p>
</div>
</li>
</ol>
</div>
<p>
For binary logging, the steps involved are listed here:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
Are there any
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-do-db">
<code class="option">
--binlog-do-db
</code>
</a>
or
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-ignore-db">
<code class="option">
--binlog-ignore-db
</code>
</a>
options?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Continue to step 2.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Log the statement and exit.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Is there a default database (has any database been selected
by
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
</code>
</a>
)?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Continue to step 3.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Ignore the statement and exit.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
There is a default database. Are there any
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-do-db">
<code class="option">
--binlog-do-db
</code>
</a>
options?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Do any of them match the database?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Log the statement and exit.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Ignore the statement and exit.
</p>
</li>
</ul>
</div>
<p>
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Continue to step 4.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Do any of the
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-ignore-db">
<code class="option">
--binlog-ignore-db
</code>
</a>
options
match the database?
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<b>
Yes.
</b>
Ignore the statement and exit.
</p>
</li>
<li class="listitem">
<p>
<b>
No.
</b>
Log the statement and exit.
</p>
</li>
</ul>
</div>
</li>
</ol>
</div>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
For statement-based logging, an exception is made in the rules
just given for the
<a class="link" href="create-database.html" title="15.1.12 CREATE DATABASE Statement">
<code class="literal">
CREATE
DATABASE
</code>
</a>
,
<a class="link" href="alter-database.html" title="15.1.2 ALTER DATABASE Statement">
<code class="literal">
ALTER
DATABASE
</code>
</a>
, and
<a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement">
<code class="literal">
DROP
DATABASE
</code>
</a>
statements. In those cases, the database
being
<span class="emphasis">
<em>
created, altered, or dropped
</em>
</span>
replaces the default database when determining whether to log
or ignore updates.
</p>
</div>
<p>
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-do-db">
<code class="option">
--binlog-do-db
</code>
</a>
can sometimes mean
<span class="quote">
“
<span class="quote">
ignore other databases
</span>
”
</span>
. For example, when using
statement-based logging, a server running with only
<a class="link" href="replication-options-binary-log.html#option_mysqld_binlog-do-db">
<code class="option">
--binlog-do-db=sales
</code>
</a>
does not
write to the binary log statements for which the default
database differs from
<code class="literal">
sales
</code>
. When using
row-based logging with the same option, the server logs only
those updates that change data in
<code class="literal">
sales
</code>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/spatial-geohash-functions.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="spatial-geohash-functions">
</a>
14.16.10 Spatial Geohash Functions
</h3>
</div>
</div>
</div>
<p>
Geohash is a system for encoding latitude and longitude
coordinates of arbitrary precision into a text string. Geohash
values are strings that contain only characters chosen from
<code class="literal">
"0123456789bcdefghjkmnpqrstuvwxyz"
</code>
.
</p>
<p>
The functions in this section enable manipulation of geohash
values, which provides applications the capabilities of importing
and exporting geohash data, and of indexing and searching geohash
values.
</p>
<p>
Unless otherwise specified, functions in this section handle their
geometry arguments as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If any argument is
<code class="literal">
NULL
</code>
, the return value
is
<code class="literal">
NULL
</code>
.
</p>
</li>
<li class="listitem">
<p>
If any argument is invalid, an error occurs.
</p>
</li>
<li class="listitem">
<p>
If any argument has a longitude or latitude that is out of
range, an error occurs:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
If a longitude value is not in the range (−180,
180], an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_geometry_param_longitude_out_of_range" target="_top">
<code class="literal">
ER_GEOMETRY_PARAM_LONGITUDE_OUT_OF_RANGE
</code>
</a>
error occurs.
</p>
</li>
<li class="listitem">
<p>
If a latitude value is not in the range [−90, 90],
an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_geometry_param_latitude_out_of_range" target="_top">
<code class="literal">
ER_GEOMETRY_PARAM_LATITUDE_OUT_OF_RANGE
</code>
</a>
error occurs.
</p>
</li>
</ul>
</div>
<p>
Ranges shown are in degrees. The exact range limits deviate
slightly due to floating-point arithmetic.
</p>
</li>
<li class="listitem">
<p>
If any point argument does not have SRID 0 or 4326, an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_srs_not_found" target="_top">
<code class="literal">
ER_SRS_NOT_FOUND
</code>
</a>
error occurs.
<em class="replaceable">
<code>
point
</code>
</em>
argument SRID validity is not
checked.
</p>
</li>
<li class="listitem">
<p>
If any SRID argument refers to an undefined spatial reference
system (SRS), an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_srs_not_found" target="_top">
<code class="literal">
ER_SRS_NOT_FOUND
</code>
</a>
error occurs.
</p>
</li>
<li class="listitem">
<p>
If any SRID argument is not within the range of a 32-bit
unsigned integer, an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_data_out_of_range" target="_top">
<code class="literal">
ER_DATA_OUT_OF_RANGE
</code>
</a>
error
occurs.
</p>
</li>
<li class="listitem">
<p>
Otherwise, the return value is non-
<code class="literal">
NULL
</code>
.
</p>
</li>
</ul>
</div>
<p>
These geohash functions are available:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a name="function_st-geohash">
</a>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-geohash">
<code class="literal">
ST_GeoHash(
<em class="replaceable">
<code>
longitude
</code>
</em>
,
<em class="replaceable">
<code>
latitude
</code>
</em>
,
<em class="replaceable">
<code>
max_length
</code>
</em>
)
</code>
</a>
,
<a class="link" href="spatial-geohash-functions.html#function_st-geohash">
<code class="literal">
ST_GeoHash(
<em class="replaceable">
<code>
point
</code>
</em>
,
<em class="replaceable">
<code>
max_length
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045196225648">
</a>
<p>
Returns a geohash string in the connection character set and
collation.
</p>
<p>
For the first syntax, the
<em class="replaceable">
<code>
longitude
</code>
</em>
must be a number in the range [−180, 180], and the
<em class="replaceable">
<code>
latitude
</code>
</em>
must be a number in the
range [−90, 90]. For the second syntax, a
<code class="literal">
POINT
</code>
value is required, where the X and Y
coordinates are in the valid ranges for longitude and
latitude, respectively.
</p>
<p>
The resulting string is no longer than
<em class="replaceable">
<code>
max_length
</code>
</em>
characters, which has an
upper limit of 100. The string might be shorter than
<em class="replaceable">
<code>
max_length
</code>
</em>
characters because the
algorithm that creates the geohash value continues until it
has created a string that is either an exact representation of
the location or
<em class="replaceable">
<code>
max_length
</code>
</em>
characters, whichever comes first.
</p>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-geohash">
<code class="literal">
ST_GeoHash()
</code>
</a>
handles its
arguments as described in the introduction to this section.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6170361"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">ST_GeoHash</span><span class="token punctuation">(</span><span class="token number">180</span><span class="token punctuation">,</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">ST_GeoHash</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">180</span><span class="token punctuation">,</span><span class="token operator">-</span><span class="token number">90</span><span class="token punctuation">,</span><span class="token number">15</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_GeoHash(180,0,10) <span class="token punctuation">|</span> ST_GeoHash(<span class="token punctuation">-</span>180,<span class="token punctuation">-</span>90,15) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> xbpbpbpbpb <span class="token punctuation">|</span> 000000000000000 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_st-latfromgeohash">
</a>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-latfromgeohash">
<code class="literal">
ST_LatFromGeoHash(
<em class="replaceable">
<code>
geohash_str
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045196209888">
</a>
<p>
Returns the latitude from a geohash string value, as a
double-precision number in the range [−90, 90].
</p>
<p>
The
<a class="link" href="spatial-geohash-functions.html#function_st-latfromgeohash">
<code class="literal">
ST_LatFromGeoHash()
</code>
</a>
decoding function reads no more than 433 characters from the
<em class="replaceable">
<code>
geohash_str
</code>
</em>
argument. That
represents the upper limit on information in the internal
representation of coordinate values. Characters past the 433rd
are ignored, even if they are otherwise illegal and produce an
error.
</p>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-latfromgeohash">
<code class="literal">
ST_LatFromGeoHash()
</code>
</a>
handles its
arguments as described in the introduction to this section.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa51125848"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">ST_LatFromGeoHash</span><span class="token punctuation">(</span><span class="token function">ST_GeoHash</span><span class="token punctuation">(</span><span class="token number">45</span><span class="token punctuation">,</span><span class="token operator">-</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_LatFromGeoHash(ST_GeoHash(45,<span class="token punctuation">-</span>20,10)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> <span class="token punctuation">-</span>20 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_st-longfromgeohash">
</a>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-longfromgeohash">
<code class="literal">
ST_LongFromGeoHash(
<em class="replaceable">
<code>
geohash_str
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045196195872">
</a>
<p>
Returns the longitude from a geohash string value, as a
double-precision number in the range [−180, 180].
</p>
<p>
The remarks in the description of
<a class="link" href="spatial-geohash-functions.html#function_st-latfromgeohash">
<code class="literal">
ST_LatFromGeoHash()
</code>
</a>
regarding
the maximum number of characters processed from the
<em class="replaceable">
<code>
geohash_str
</code>
</em>
argument also apply to
<a class="link" href="spatial-geohash-functions.html#function_st-longfromgeohash">
<code class="literal">
ST_LongFromGeoHash()
</code>
</a>
.
</p>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-longfromgeohash">
<code class="literal">
ST_LongFromGeoHash()
</code>
</a>
handles
its arguments as described in the introduction to this
section.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa36927377"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">ST_LongFromGeoHash</span><span class="token punctuation">(</span><span class="token function">ST_GeoHash</span><span class="token punctuation">(</span><span class="token number">45</span><span class="token punctuation">,</span><span class="token operator">-</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_LongFromGeoHash(ST_GeoHash(45,<span class="token punctuation">-</span>20,10)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 45 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<a name="function_st-pointfromgeohash">
</a>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-pointfromgeohash">
<code class="literal">
ST_PointFromGeoHash(
<em class="replaceable">
<code>
geohash_str
</code>
</em>
,
<em class="replaceable">
<code>
srid
</code>
</em>
)
</code>
</a>
</p>
<a class="indexterm" name="idm46045196180592">
</a>
<p>
Returns a
<code class="literal">
POINT
</code>
value containing the
decoded geohash value, given a geohash string value.
</p>
<p>
The X and Y coordinates of the point are the longitude in the
range [−180, 180] and the latitude in the range
[−90, 90], respectively.
</p>
<p>
The
<em class="replaceable">
<code>
srid
</code>
</em>
argument is an 32-bit
unsigned integer.
</p>
<p>
The remarks in the description of
<a class="link" href="spatial-geohash-functions.html#function_st-latfromgeohash">
<code class="literal">
ST_LatFromGeoHash()
</code>
</a>
regarding
the maximum number of characters processed from the
<em class="replaceable">
<code>
geohash_str
</code>
</em>
argument also apply to
<a class="link" href="spatial-geohash-functions.html#function_st-pointfromgeohash">
<code class="literal">
ST_PointFromGeoHash()
</code>
</a>
.
</p>
<p>
<a class="link" href="spatial-geohash-functions.html#function_st-pointfromgeohash">
<code class="literal">
ST_PointFromGeoHash()
</code>
</a>
handles
its arguments as described in the introduction to this
section.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86999179"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@gh</span> <span class="token operator">=</span> <span class="token function">ST_GeoHash</span><span class="token punctuation">(</span><span class="token number">45</span><span class="token punctuation">,</span><span class="token operator">-</span><span class="token number">20</span><span class="token punctuation">,</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">ST_AsText</span><span class="token punctuation">(</span><span class="token function">ST_PointFromGeoHash</span><span class="token punctuation">(</span><span class="token variable">@gh</span><span class="token punctuation">,</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> ST_AsText(ST_PointFromGeoHash(@gh,0)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> POINT(45 <span class="token punctuation">-</span>20) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/multiple-server-clients.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="multiple-server-clients">
</a>
7.8.4 Using Client Programs in a Multiple-Server Environment
</h3>
</div>
</div>
</div>
<p>
To connect with a client program to a MySQL server that is
listening to different network interfaces from those compiled into
your client, you can use one of the following methods:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Start the client with
<a class="link" href="connection-options.html#option_general_host">
<code class="option">
--host=
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
</a>
<a class="link" href="connection-options.html#option_general_port">
<code class="option">
--port=
<em class="replaceable">
<code>
port_number
</code>
</em>
</code>
</a>
to connect using TCP/IP to a remote server, with
<a class="link" href="connection-options.html#option_general_host">
<code class="option">
--host=127.0.0.1
</code>
</a>
<a class="link" href="connection-options.html#option_general_port">
<code class="option">
--port=
<em class="replaceable">
<code>
port_number
</code>
</em>
</code>
</a>
to connect using TCP/IP to a local server, or with
<a class="link" href="connection-options.html#option_general_host">
<code class="option">
--host=localhost
</code>
</a>
<a class="link" href="connection-options.html#option_general_socket">
<code class="option">
--socket=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
to connect to a local server using a Unix socket file or a
Windows named pipe.
</p>
</li>
<li class="listitem">
<p>
Start the client with
<a class="link" href="connection-options.html#option_general_protocol">
<code class="option">
--protocol=TCP
</code>
</a>
to connect
using TCP/IP,
<a class="link" href="connection-options.html#option_general_protocol">
<code class="option">
--protocol=SOCKET
</code>
</a>
to connect
using a Unix socket file,
<a class="link" href="connection-options.html#option_general_protocol">
<code class="option">
--protocol=PIPE
</code>
</a>
to connect
using a named pipe, or
<a class="link" href="connection-options.html#option_general_protocol">
<code class="option">
--protocol=MEMORY
</code>
</a>
to connect
using shared memory. For TCP/IP connections, you may also need
to specify
<a class="link" href="connection-options.html#option_general_host">
<code class="option">
--host
</code>
</a>
and
<a class="link" href="connection-options.html#option_general_port">
<code class="option">
--port
</code>
</a>
options. For the other
types of connections, you may need to specify a
<a class="link" href="connection-options.html#option_general_socket">
<code class="option">
--socket
</code>
</a>
option to specify a
Unix socket file or Windows named-pipe name, or a
<a class="link" href="connection-options.html#option_general_shared-memory-base-name">
<code class="option">
--shared-memory-base-name
</code>
</a>
option to specify the shared-memory name. Shared-memory
connections are supported only on Windows.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045253890288">
</a>
<a class="indexterm" name="idm46045253889200">
</a>
<a class="indexterm" name="idm46045253888112">
</a>
<a class="indexterm" name="idm46045253886624">
</a>
On Unix, set the
<code class="literal">
MYSQL_UNIX_PORT
</code>
and
<code class="literal">
MYSQL_TCP_PORT
</code>
environment variables to
point to the Unix socket file and TCP/IP port number before
you start your clients. If you normally use a specific socket
file or port number, you can place commands to set these
environment variables in your
<code class="filename">
.login
</code>
file
so that they apply each time you log in. See
<a class="xref" href="environment-variables.html" title="6.9 Environment Variables">
Section 6.9, “Environment Variables”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Specify the default Unix socket file and TCP/IP port number in
the
<code class="literal">
[client]
</code>
group of an option file. For
example, you can use
<code class="filename">
C:\my.cnf
</code>
on
Windows, or the
<code class="filename">
.my.cnf
</code>
file in your home
directory on Unix. See
<a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files">
Section 6.2.2.2, “Using Option Files”
</a>
.
</p>
<a class="indexterm" name="idm46045253878016">
</a>
<a class="indexterm" name="idm46045253876944">
</a>
<a class="indexterm" name="idm46045253875456">
</a>
<a class="indexterm" name="idm46045253874384">
</a>
</li>
<li class="listitem">
<p>
In a C program, you can specify the socket file or port number
arguments in the
<a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top">
<code class="literal">
mysql_real_connect()
</code>
</a>
call. You
can also have the program read option files by calling
<a class="ulink" href="/doc/c-api/8.4/en/mysql-options.html" target="_top">
<code class="literal">
mysql_options()
</code>
</a>
. See
<a class="ulink" href="/doc/c-api/8.4/en/c-api-function-descriptions.html" target="_top">
C API Basic Function Descriptions
</a>
.
</p>
</li>
<li class="listitem">
<p>
If you are using the Perl
<code class="literal">
DBD::mysql
</code>
module, you can read options from MySQL option files. For
example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-perl"><div class="docs-select-all right" id="sa76111401"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-perl"><span class="token variable">$dsn</span> <span class="token operator">=</span> <span class="token string">"DBI:mysql:test;mysql_read_default_group=client;"</span>
<span class="token operator">.</span> <span class="token string">"mysql_read_default_file=/usr/local/mysql/data/my.cnf"</span><span class="token punctuation">;</span>
<span class="token variable">$dbh</span> <span class="token operator">=</span> DBI<span class="token operator">-></span>connect<span class="token punctuation">(</span><span class="token variable">$dsn</span><span class="token punctuation">,</span> <span class="token variable">$user</span><span class="token punctuation">,</span> <span class="token variable">$password</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
See
<a class="xref" href="apis-perl.html" title="31.9 MySQL Perl API">
Section 31.9, “MySQL Perl API”
</a>
.
</p>
<p>
Other programming interfaces may provide similar capabilities
for reading option files.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/group-replication-plugin-architecture.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="group-replication-plugin-architecture">
</a>
20.1.5 Group Replication Plugin Architecture
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045134316336">
</a>
<a class="indexterm" name="idm46045134314848">
</a>
<a class="indexterm" name="idm46045134313344">
</a>
<p>
MySQL Group Replication is a MySQL plugin and it builds on the
existing MySQL replication infrastructure, taking advantage of
features such as the binary log, row-based logging, and global
transaction identifiers. It integrates with current MySQL
frameworks, such as the performance schema or plugin and service
infrastructures. The following figure presents a block diagram
depicting the overall architecture of MySQL Group Replication.
</p>
<div class="figure">
<a name="idm46045134310976">
</a>
<p class="title">
<b>
Figure 20.6 Group Replication Plugin Block Diagram
</b>
</p>
<div class="figure-contents">
<div class="mediaobject">
<img alt="The text following the figure describes the content of the diagram." src="images/gr-plugin-blocks.png" style="width: 100%; max-width: 391px;"/>
</div>
</div>
</div>
<br class="figure-break"/>
<p>
The MySQL Group Replication plugin includes a set of APIs for
capture, apply, and lifecycle, which control how the plugin
interacts with MySQL Server. There are interfaces to make
information flow from the server to the plugin and vice versa.
These interfaces isolate the MySQL Server core from the Group
Replication plugin, and are mostly hooks placed in the transaction
execution pipeline. In one direction, from server to the plugin,
there are notifications for events such as the server starting,
the server recovering, the server being ready to accept
connections, and the server being about to commit a transaction.
In the other direction, the plugin instructs the server to perform
actions such as committing or aborting ongoing transactions, or
queuing transactions in the relay log.
</p>
<p>
The next layer of the Group Replication plugin architecture is a
set of components that react when a notification is routed to
them. The capture component is responsible for keeping track of
context related to transactions that are executing. The applier
component is responsible for executing remote transactions on the
database. The recovery component manages distributed recovery, and
is responsible for getting a server that is joining the group up
to date by selecting the donor, managing the catch up procedure
and reacting to donor failures.
</p>
<p>
Continuing down the stack, the replication protocol module
contains the specific logic of the replication protocol. It
handles conflict detection, and receives and propagates
transactions to the group.
</p>
<p>
The final two layers of the Group Replication plugin architecture
are the Group Communication System (GCS) API, and an
implementation of a Paxos-based group communication engine (XCom).
The GCS API is a high level API that abstracts the properties
required to build a replicated state machine (see
<a class="xref" href="group-replication-background.html" title="20.1 Group Replication Background">
Section 20.1, “Group Replication Background”
</a>
). It therefore
decouples the implementation of the messaging layer from the
remaining upper layers of the plugin. The group communication
engine handles communications with the members of the replication
group.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndb-transporter-errors.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-ndb-transporter-errors">
</a>
25.6.2.4 NDB Cluster: NDB Transporter Errors
</h4>
</div>
</div>
</div>
<p>
This section lists error codes, names, and messages that are
written to the cluster log in the event of transporter errors.
</p>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<span class="errorcode">
0x00
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_NO_ERROR
</span>
</p>
<p>
<span class="errortext">
No error
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x01
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_ERROR_CLOSING_SOCKET
</span>
</p>
<p>
<span class="errortext">
Error found during closing of
socket
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x02
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_ERROR_IN_SELECT_BEFORE_ACCEPT
</span>
</p>
<p>
<span class="errortext">
Error found before accept. The transporter will
retry
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x03
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_INVALID_MESSAGE_LENGTH
</span>
</p>
<p>
<span class="errortext">
Error found in message (invalid message
length)
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x04
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_INVALID_CHECKSUM
</span>
</p>
<p>
<span class="errortext">
Error found in message (checksum)
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x05
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_COULD_NOT_CREATE_SOCKET
</span>
</p>
<p>
<span class="errortext">
Error found while creating socket(can't create
socket)
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x06
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_COULD_NOT_BIND_SOCKET
</span>
</p>
<p>
<span class="errortext">
Error found while binding server
socket
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x07
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_LISTEN_FAILED
</span>
</p>
<p>
<span class="errortext">
Error found while listening to server
socket
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x08
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_ACCEPT_RETURN_ERROR
</span>
</p>
<p>
<span class="errortext">
Error found during accept(accept return
error)
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x0b
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_DISCONNECT
</span>
</p>
<p>
<span class="errortext">
The remote node has disconnected
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x0c
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_IPC_STAT
</span>
</p>
<p>
<span class="errortext">
Unable to check shm segment
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x0d
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_UNABLE_TO_CREATE_SEGMENT
</span>
</p>
<p>
<span class="errortext">
Unable to create shm segment
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x0e
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_UNABLE_TO_ATTACH_SEGMENT
</span>
</p>
<p>
<span class="errortext">
Unable to attach shm segment
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x0f
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_UNABLE_TO_REMOVE_SEGMENT
</span>
</p>
<p>
<span class="errortext">
Unable to remove shm segment
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x10
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_TOO_SMALL_SIGID
</span>
</p>
<p>
<span class="errortext">
Sig ID too small
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x11
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_TOO_LARGE_SIGID
</span>
</p>
<p>
<span class="errortext">
Sig ID too large
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x12
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_WAIT_STACK_FULL
</span>
</p>
<p>
<span class="errortext">
Wait stack was full
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x13
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_RECEIVE_BUFFER_FULL
</span>
</p>
<p>
<span class="errortext">
Receive buffer was full
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x14
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SIGNAL_LOST_SEND_BUFFER_FULL
</span>
</p>
<p>
<span class="errortext">
Send buffer was full,and trying to force send
fails
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x15
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SIGNAL_LOST
</span>
</p>
<p>
<span class="errortext">
Send failed for unknown reason(signal
lost)
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x16
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SEND_BUFFER_FULL
</span>
</p>
<p>
<span class="errortext">
The send buffer was full, but sleeping for a
while solved
</span>
</p>
</dd>
<dt>
<span class="term">
<span class="errorcode">
0x21
</span>
</span>
</dt>
<dd>
<p>
<span class="errorname">
TE_SHM_IPC_PERMANENT
</span>
</p>
<p>
<span class="errortext">
Shm ipc Permanent error
</span>
</p>
</dd>
</dl>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Transporter error codes
<span class="errorcode">
0x17
</span>
through
<span class="errorcode">
0x20
</span>
and
<span class="errorcode">
0x22
</span>
are reserved for SCI connections, which are not supported in
this version of NDB Cluster, and so are not included here.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/set-character-set.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="set-character-set">
</a>
15.7.6.2 SET CHARACTER SET Statement
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045171364240">
</a>
<a class="indexterm" name="idm46045171363184">
</a>
<a class="indexterm" name="idm46045171362112">
</a>
<a class="indexterm" name="idm46045171360624">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35473692"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> {<span class="token keyword">CHARACTER</span> <span class="token keyword">SET</span> <span class="token operator">|</span> <span class="token keyword">CHARSET</span>}
{<span class="token string">'<em class="replaceable">charset_name</em>'</span> <span class="token operator">|</span> <span class="token keyword">DEFAULT</span>}</code></pre>
</div>
<p>
This statement maps all strings sent between the server and the
current client with the given mapping.
<code class="literal">
SET CHARACTER
SET
</code>
sets three session system variables:
<a class="link" href="server-system-variables.html#sysvar_character_set_client">
<code class="literal">
character_set_client
</code>
</a>
and
<a class="link" href="server-system-variables.html#sysvar_character_set_results">
<code class="literal">
character_set_results
</code>
</a>
are set
to the given character set, and
<a class="link" href="server-system-variables.html#sysvar_character_set_connection">
<code class="literal">
character_set_connection
</code>
</a>
to the
value of
<a class="link" href="server-system-variables.html#sysvar_character_set_database">
<code class="literal">
character_set_database
</code>
</a>
. See
<a class="xref" href="charset-connection.html" title="12.4 Connection Character Sets and Collations">
Section 12.4, “Connection Character Sets and Collations”
</a>
.
</p>
<p>
<em class="replaceable">
<code>
charset_name
</code>
</em>
may be quoted or
unquoted.
</p>
<p>
The default character set mapping can be restored by using the
value
<code class="literal">
DEFAULT
</code>
. The default depends on the
server configuration.
</p>
<p>
Some character sets cannot be used as the client character set.
Attempting to use them with
<a class="link" href="set-character-set.html" title="15.7.6.2 SET CHARACTER SET Statement">
<code class="literal">
SET CHARACTER
SET
</code>
</a>
produces an error. See
<a class="xref" href="charset-connection.html#charset-connection-impermissible-client-charset" title="Impermissible Client Character Sets">
Impermissible Client Character Sets
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/information-schema-st-units-of-measure-table.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="information-schema-st-units-of-measure-table">
</a>
28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045078486048">
</a>
<p>
The
<a class="link" href="information-schema-st-units-of-measure-table.html" title="28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table">
<code class="literal">
ST_UNITS_OF_MEASURE
</code>
</a>
table
provides information about acceptable units for the
<a class="link" href="spatial-relation-functions-object-shapes.html#function_st-distance">
<code class="literal">
ST_Distance()
</code>
</a>
function.
</p>
<p>
The
<a class="link" href="information-schema-st-units-of-measure-table.html" title="28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table">
<code class="literal">
ST_UNITS_OF_MEASURE
</code>
</a>
table has
these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
UNIT_NAME
</code>
</p>
<p>
The name of the unit.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
UNIT_TYPE
</code>
</p>
<p>
The unit type (for example,
<code class="literal">
LINEAR
</code>
).
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
CONVERSION_FACTOR
</code>
</p>
<p>
A conversion factor used for internal calculations.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
DESCRIPTION
</code>
</p>
<p>
A description of the unit.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-features-optimizer.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="replication-features-optimizer">
</a>
19.5.1.23 Replication and the Query Optimizer
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045135262208">
</a>
<a class="indexterm" name="idm46045135260720">
</a>
<p>
It is possible for the data on the source and replica to become
different if a statement is written in such a way that the data
modification is nondeterministic; that is, left up the query
optimizer. (In general, this is not a good practice, even
outside of replication.) Examples of nondeterministic statements
include
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
or
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statements that use
<code class="literal">
LIMIT
</code>
with no
<code class="literal">
ORDER BY
</code>
clause; see
<a class="xref" href="replication-features-limit.html" title="19.5.1.18 Replication and LIMIT">
Section 19.5.1.18, “Replication and LIMIT”
</a>
, for a
detailed discussion of these.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/storage-engines.html | <div id="docs-body">
<div class="chapter">
<div class="titlepage">
<div>
<div>
<h1 class="title">
<a name="storage-engines">
</a>
Chapter 18 Alternative Storage Engines
</h1>
</div>
</div>
</div>
<div class="toc">
<p>
<b>
Table of Contents
</b>
</p>
<dl class="toc">
<dt>
<span class="section">
<a href="storage-engine-setting.html">
18.1 Setting the Storage Engine
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="myisam-storage-engine.html">
18.2 The MyISAM Storage Engine
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="myisam-start.html">
18.2.1 MyISAM Startup Options
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="key-space.html">
18.2.2 Space Needed for Keys
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="myisam-table-formats.html">
18.2.3 MyISAM Table Storage Formats
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="myisam-table-problems.html">
18.2.4 MyISAM Table Problems
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="memory-storage-engine.html">
18.3 The MEMORY Storage Engine
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="csv-storage-engine.html">
18.4 The CSV Storage Engine
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="se-csv-repair.html">
18.4.1 Repairing and Checking CSV Tables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="se-csv-limitations.html">
18.4.2 CSV Limitations
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="archive-storage-engine.html">
18.5 The ARCHIVE Storage Engine
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="blackhole-storage-engine.html">
18.6 The BLACKHOLE Storage Engine
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="merge-storage-engine.html">
18.7 The MERGE Storage Engine
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="merge-table-advantages.html">
18.7.1 MERGE Table Advantages and Disadvantages
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="merge-table-problems.html">
18.7.2 MERGE Table Problems
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="federated-storage-engine.html">
18.8 The FEDERATED Storage Engine
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="federated-description.html">
18.8.1 FEDERATED Storage Engine Overview
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="federated-create.html">
18.8.2 How to Create FEDERATED Tables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="federated-usagenotes.html">
18.8.3 FEDERATED Storage Engine Notes and Tips
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="federated-storage-engine-resources.html">
18.8.4 FEDERATED Storage Engine Resources
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="example-storage-engine.html">
18.9 The EXAMPLE Storage Engine
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="storage-engines-other.html">
18.10 Other Storage Engines
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="pluggable-storage-overview.html">
18.11 Overview of MySQL Storage Engine Architecture
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="pluggable-storage.html">
18.11.1 Pluggable Storage Engine Architecture
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="pluggable-storage-common-layer.html">
18.11.2 The Common Database Server Layer
</a>
</span>
</dt>
</dl>
</dd>
</dl>
</div>
<a class="indexterm" name="idm46045148723456">
</a>
<a class="indexterm" name="idm46045148722000">
</a>
<a class="indexterm" name="idm46045148720512">
</a>
<a class="indexterm" name="idm46045148719024">
</a>
<a class="indexterm" name="idm46045148717952">
</a>
<a class="indexterm" name="idm46045148716880">
</a>
<a class="indexterm" name="idm46045148715808">
</a>
<a class="indexterm" name="idm46045148714736">
</a>
<a class="indexterm" name="idm46045148713664">
</a>
<a class="indexterm" name="idm46045148712592">
</a>
<a class="indexterm" name="idm46045148711520">
</a>
<a class="indexterm" name="idm46045148710448">
</a>
<a class="indexterm" name="idm46045148709376">
</a>
<a class="indexterm" name="idm46045148708288">
</a>
<p>
Storage engines are MySQL components that handle the SQL operations
for different table types.
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
is
the default and most general-purpose storage engine, and Oracle
recommends using it for tables except for specialized use cases.
(The
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statement in MySQL
8.4 creates
<code class="literal">
InnoDB
</code>
tables by
default.)
</p>
<p>
MySQL Server uses a pluggable storage engine architecture that
enables storage engines to be loaded into and unloaded from a
running MySQL server.
</p>
<p>
To determine which storage engines your server supports, use the
<a class="link" href="show-engines.html" title="15.7.7.17 SHOW ENGINES Statement">
<code class="literal">
SHOW ENGINES
</code>
</a>
statement. The value in
the
<code class="literal">
Support
</code>
column indicates whether an engine
can be used. A value of
<code class="literal">
YES
</code>
,
<code class="literal">
NO
</code>
, or
<code class="literal">
DEFAULT
</code>
indicates that
an engine is available, not available, or available and currently
set as the default storage engine.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa43094108"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">ENGINES</span>\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Engine<span class="token punctuation">:</span> PERFORMANCE_SCHEMA
Support<span class="token punctuation">:</span> YES
Comment<span class="token punctuation">:</span> Performance Schema
Transactions<span class="token punctuation">:</span> NO
XA<span class="token punctuation">:</span> NO
Savepoints<span class="token punctuation">:</span> NO
<span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 2. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Engine<span class="token punctuation">:</span> InnoDB
Support<span class="token punctuation">:</span> DEFAULT
Comment<span class="token punctuation">:</span> Supports transactions, row-level locking, and foreign keys
Transactions<span class="token punctuation">:</span> YES
XA<span class="token punctuation">:</span> YES
Savepoints<span class="token punctuation">:</span> YES
<span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 3. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Engine<span class="token punctuation">:</span> MRG_MYISAM
Support<span class="token punctuation">:</span> YES
Comment<span class="token punctuation">:</span> Collection of identical MyISAM tables
Transactions<span class="token punctuation">:</span> NO
XA<span class="token punctuation">:</span> NO
Savepoints<span class="token punctuation">:</span> NO
<span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 4. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Engine<span class="token punctuation">:</span> BLACKHOLE
Support<span class="token punctuation">:</span> YES
Comment<span class="token punctuation">:</span> /dev/null storage engine (anything you write to it disappears)
Transactions<span class="token punctuation">:</span> NO
XA<span class="token punctuation">:</span> NO
Savepoints<span class="token punctuation">:</span> NO
<span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 5. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Engine<span class="token punctuation">:</span> MyISAM
Support<span class="token punctuation">:</span> YES
Comment<span class="token punctuation">:</span> MyISAM storage engine
Transactions<span class="token punctuation">:</span> NO
XA<span class="token punctuation">:</span> NO
Savepoints<span class="token punctuation">:</span> NO
...</span></code></pre>
</div>
<p>
This chapter covers use cases for special-purpose MySQL storage
engines. It does not cover the default
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
storage engine or the
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
storage engine which are covered in
<a class="xref" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
Chapter 17,
<i>
The InnoDB Storage Engine
</i>
</a>
and
<a class="xref" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
Chapter 25,
<i>
MySQL NDB Cluster 8.4
</i>
</a>
. For advanced users, it also
contains a description of the pluggable storage engine architecture
(see
<a class="xref" href="pluggable-storage-overview.html" title="18.11 Overview of MySQL Storage Engine Architecture">
Section 18.11, “Overview of MySQL Storage Engine Architecture”
</a>
).
</p>
<p>
For information about features offered in commercial MySQL Server
binaries, see
<a class="ulink" href="https://www.mysql.com/products/" target="_blank">
<em class="citetitle">
MySQL
Editions
</em>
</a>
, on the MySQL website. The storage
engines available might depend on which edition of MySQL you are
using.
</p>
<p>
For answers to commonly asked questions about MySQL storage engines,
see
<a class="xref" href="faqs-storage-engines.html" title="A.2 MySQL 8.4 FAQ: Storage Engines">
Section A.2, “MySQL 8.4 FAQ: Storage Engines”
</a>
.
</p>
<h2>
<a name="idm46045148686400">
</a>
MySQL 8.4 Supported Storage Engines
</h2>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
:
The default storage engine in MySQL 8.4.
<code class="literal">
InnoDB
</code>
is a transaction-safe (ACID compliant)
storage engine for MySQL that has commit, rollback, and
crash-recovery capabilities to protect user data.
<code class="literal">
InnoDB
</code>
row-level locking (without escalation
to coarser granularity locks) and Oracle-style consistent
nonlocking reads increase multi-user concurrency and
performance.
<code class="literal">
InnoDB
</code>
stores user data in
clustered indexes to reduce I/O for common queries based on
primary keys. To maintain data integrity,
<code class="literal">
InnoDB
</code>
also supports
<code class="literal">
FOREIGN
KEY
</code>
referential-integrity constraints. For more
information about
<code class="literal">
InnoDB
</code>
, see
<a class="xref" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
Chapter 17,
<i>
The InnoDB Storage Engine
</i>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine">
<code class="literal">
MyISAM
</code>
</a>
:
These tables have a small footprint.
<a class="link" href="glossary.html#glos_table_lock" title="table lock">
Table-level locking
</a>
limits the performance in read/write workloads, so it is often
used in read-only or read-mostly workloads in Web and data
warehousing configurations.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="memory-storage-engine.html" title="18.3 The MEMORY Storage Engine">
<code class="literal">
Memory
</code>
</a>
:
Stores all data in RAM, for fast access in environments that
require quick lookups of non-critical data. This engine was
formerly known as the
<code class="literal">
HEAP
</code>
engine. Its use
cases are decreasing;
<code class="literal">
InnoDB
</code>
with its buffer
pool memory area provides a general-purpose and durable way to
keep most or all data in memory, and
<code class="literal">
NDBCLUSTER
</code>
provides fast key-value lookups
for huge distributed data sets.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="csv-storage-engine.html" title="18.4 The CSV Storage Engine">
<code class="literal">
CSV
</code>
</a>
:
Its tables are really text files with comma-separated values.
CSV tables let you import or dump data in CSV format, to
exchange data with scripts and applications that read and write
that same format. Because CSV tables are not indexed, you
typically keep the data in
<code class="literal">
InnoDB
</code>
tables
during normal operation, and only use CSV tables during the
import or export stage.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="archive-storage-engine.html" title="18.5 The ARCHIVE Storage Engine">
<code class="literal">
Archive
</code>
</a>
:
These compact, unindexed tables are intended for storing and
retrieving large amounts of seldom-referenced historical,
archived, or security audit information.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="blackhole-storage-engine.html" title="18.6 The BLACKHOLE Storage Engine">
<code class="literal">
Blackhole
</code>
</a>
:
The Blackhole storage engine accepts but does not store data,
similar to the Unix
<code class="literal">
/dev/null
</code>
device. Queries
always return an empty set. These tables can be used in
replication configurations where DML statements are sent to
replica servers, but the source server does not keep its own
copy of the data.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
(also known as
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDBCLUSTER
</code>
</a>
): This clustered
database engine is particularly suited for applications that
require the highest possible degree of uptime and availability.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="merge-storage-engine.html" title="18.7 The MERGE Storage Engine">
<code class="literal">
Merge
</code>
</a>
:
Enables a MySQL DBA or developer to logically group a series of
identical
<code class="literal">
MyISAM
</code>
tables and reference them as
one object. Good for VLDB environments such as data warehousing.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="federated-storage-engine.html" title="18.8 The FEDERATED Storage Engine">
<code class="literal">
Federated
</code>
</a>
:
Offers the ability to link separate MySQL servers to create one
logical database from many physical servers. Very good for
distributed or data mart environments.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="example-storage-engine.html" title="18.9 The EXAMPLE Storage Engine">
<code class="literal">
Example
</code>
</a>
:
This engine serves as an example in the MySQL source code that
illustrates how to begin writing new storage engines. It is
primarily of interest to developers. The storage engine is a
<span class="quote">
“
<span class="quote">
stub
</span>
”
</span>
that does nothing. You can create tables
with this engine, but no data can be stored in them or retrieved
from them.
</p>
</li>
</ul>
</div>
<p>
You are not restricted to using the same storage engine for an
entire server or schema. You can specify the storage engine for any
table. For example, an application might use mostly
<code class="literal">
InnoDB
</code>
tables, with one
<code class="literal">
CSV
</code>
table for exporting data to a spreadsheet and a few
<code class="literal">
MEMORY
</code>
tables for temporary workspaces.
</p>
<p>
<span class="bold">
<strong>
Choosing a Storage Engine
</strong>
</span>
</p>
<p>
The various storage engines provided with MySQL are designed with
different use cases in mind. The following table provides an
overview of some storage engines provided with MySQL, with
clarifying notes following the table.
</p>
<div class="table">
<a name="idm46045148645968">
</a>
<p class="title">
<b>
Table 18.1 Storage Engines Feature Summary
</b>
</p>
<div class="table-contents">
<table frame="box" rules="all" summary="Summary of features supported per storage engine.">
<colgroup>
<col style="width: 10%"/>
<col style="width: 16%"/>
<col style="width: 16%"/>
<col style="width: 16%"/>
<col style="width: 16%"/>
<col style="width: 16%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Feature
</th>
<th scope="col">
MyISAM
</th>
<th scope="col">
Memory
</th>
<th scope="col">
InnoDB
</th>
<th scope="col">
Archive
</th>
<th scope="col">
NDB
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
B-tree indexes
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Backup/point-in-time recovery (note 1)
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Cluster database support
</th>
<td>
No
</td>
<td>
No
</td>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Clustered indexes
</th>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Compressed data
</th>
<td>
Yes (note 2)
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Data caches
</th>
<td>
No
</td>
<td>
N/A
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Encrypted data
</th>
<td>
Yes (note 3)
</td>
<td>
Yes (note 3)
</td>
<td>
Yes (note 4)
</td>
<td>
Yes (note 3)
</td>
<td>
Yes (note 5)
</td>
</tr>
<tr>
<th scope="row">
Foreign key support
</th>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Full-text search indexes
</th>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes (note 6)
</td>
<td>
No
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Geospatial data type support
</th>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Geospatial indexing support
</th>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes (note 7)
</td>
<td>
No
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Hash indexes
</th>
<td>
No
</td>
<td>
Yes
</td>
<td>
No (note 8)
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Index caches
</th>
<td>
Yes
</td>
<td>
N/A
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Locking granularity
</th>
<td>
Table
</td>
<td>
Table
</td>
<td>
Row
</td>
<td>
Row
</td>
<td>
Row
</td>
</tr>
<tr>
<th scope="row">
MVCC
</th>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
No
</td>
</tr>
<tr>
<th scope="row">
Replication support (note 1)
</th>
<td>
Yes
</td>
<td>
Limited (note 9)
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Storage limits
</th>
<td>
256TB
</td>
<td>
RAM
</td>
<td>
64TB
</td>
<td>
None
</td>
<td>
384EB
</td>
</tr>
<tr>
<th scope="row">
T-tree indexes
</th>
<td>
No
</td>
<td>
No
</td>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Transactions
</th>
<td>
No
</td>
<td>
No
</td>
<td>
Yes
</td>
<td>
No
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
Update statistics for data dictionary
</th>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
<td>
Yes
</td>
</tr>
</tbody>
</table>
</div>
<div class="table-contents">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;">
<thead>
<tr>
<th scope="col" style="width: 112.359px;">
Feature
</th>
<th scope="col" style="width: 125.125px;">
MyISAM
</th>
<th scope="col" style="width: 125.125px;">
Memory
</th>
<th scope="col" style="width: 125.125px;">
InnoDB
</th>
<th scope="col" style="width: 125.125px;">
Archive
</th>
<th scope="col" style="width: 125.141px;">
NDB
</th>
</tr>
</thead>
</table>
</div>
</div>
<br class="table-break"/>
<p>
<span class="bold">
<strong>
Notes:
</strong>
</span>
</p>
<p>
1. Implemented in the server, rather than in the storage engine.
</p>
<p>
2. Compressed MyISAM tables are supported only when using the compressed row format. Tables using the compressed row format with MyISAM are read only.
</p>
<p>
3. Implemented in the server via encryption functions.
</p>
<p>
4. Implemented in the server via encryption functions; In MySQL 5.7 and later, data-at-rest encryption is supported.
</p>
<p>
5. Implemented in the server via encryption functions; encrypted NDB backups as of NDB 8.0.22; transparent NDB file system encryption supported in NDB 8.0.29 and later.
</p>
<p>
6. Support for FULLTEXT indexes is available in MySQL 5.6 and later.
</p>
<p>
7. Support for geospatial indexing is available in MySQL 5.7 and later.
</p>
<p>
8. InnoDB utilizes hash indexes internally for its Adaptive Hash Index feature.
</p>
<p>
9. See the discussion later in this section.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/commit.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="commit">
</a>
15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045178890640">
</a>
<a class="indexterm" name="idm46045178889600">
</a>
<a class="indexterm" name="idm46045178888528">
</a>
<a class="indexterm" name="idm46045178887456">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6225457"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">START</span> <span class="token keyword">TRANSACTION</span>
<span class="token punctuation">[</span><em class="replaceable">transaction_characteristic</em> <span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">transaction_characteristic</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span>
<em class="replaceable">transaction_characteristic</em>: {
<span class="token keyword">WITH</span> <span class="token keyword">CONSISTENT</span> <span class="token keyword">SNAPSHOT</span>
<span class="token operator">|</span> <span class="token keyword">READ</span> <span class="token keyword">WRITE</span>
<span class="token operator">|</span> <span class="token keyword">READ</span> <span class="token keyword">ONLY</span>
}
<span class="token keyword">BEGIN</span> <span class="token punctuation">[</span><span class="token keyword">WORK</span><span class="token punctuation">]</span>
<span class="token keyword">COMMIT</span> <span class="token punctuation">[</span><span class="token keyword">WORK</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token operator">AND</span> <span class="token punctuation">[</span><span class="token keyword">NO</span><span class="token punctuation">]</span> <span class="token keyword">CHAIN</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token punctuation">[</span><span class="token keyword">NO</span><span class="token punctuation">]</span> <span class="token keyword">RELEASE</span><span class="token punctuation">]</span>
<span class="token keyword">ROLLBACK</span> <span class="token punctuation">[</span><span class="token keyword">WORK</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token operator">AND</span> <span class="token punctuation">[</span><span class="token keyword">NO</span><span class="token punctuation">]</span> <span class="token keyword">CHAIN</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token punctuation">[</span><span class="token keyword">NO</span><span class="token punctuation">]</span> <span class="token keyword">RELEASE</span><span class="token punctuation">]</span>
<span class="token keyword">SET</span> autocommit <span class="token operator">=</span> {<span class="token number">0</span> <span class="token operator">|</span> <span class="token number">1</span>}</code></pre>
</div>
<p>
These statements provide control over use of
<a class="link" href="glossary.html#glos_transaction" title="transaction">
transactions
</a>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
START TRANSACTION
</code>
or
<code class="literal">
BEGIN
</code>
start a new transaction.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
COMMIT
</code>
commits the current transaction,
making its changes permanent.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ROLLBACK
</code>
rolls back the current
transaction, canceling its changes.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
SET autocommit
</code>
disables or enables the
default autocommit mode for the current session.
</p>
</li>
</ul>
</div>
<p>
By default, MySQL runs with
<a class="link" href="glossary.html#glos_autocommit" title="autocommit">
autocommit
</a>
mode enabled.
This means that, when not otherwise inside a transaction, each
statement is atomic, as if it were surrounded by
<code class="literal">
START
TRANSACTION
</code>
and
<code class="literal">
COMMIT
</code>
. You cannot
use
<code class="literal">
ROLLBACK
</code>
to undo the effect; however, if an
error occurs during statement execution, the statement is rolled
back.
</p>
<p>
To disable autocommit mode implicitly for a single series of
statements, use the
<code class="literal">
START TRANSACTION
</code>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33565911"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">START</span> <span class="token keyword">TRANSACTION</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> <span class="token variable">@A</span><span class="token operator">:=</span><span class="token function">SUM</span><span class="token punctuation">(</span>salary<span class="token punctuation">)</span> <span class="token keyword">FROM</span> table1 <span class="token keyword">WHERE</span> <span class="token keyword">type</span><span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">;</span>
<span class="token keyword">UPDATE</span> table2 <span class="token keyword">SET</span> summary<span class="token operator">=</span><span class="token variable">@A</span> <span class="token keyword">WHERE</span> <span class="token keyword">type</span><span class="token operator">=</span><span class="token number">1</span><span class="token punctuation">;</span>
<span class="token keyword">COMMIT</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
With
<code class="literal">
START TRANSACTION
</code>
, autocommit remains
disabled until you end the transaction with
<code class="literal">
COMMIT
</code>
or
<code class="literal">
ROLLBACK
</code>
. The
autocommit mode then reverts to its previous state.
</p>
<p>
<code class="literal">
START TRANSACTION
</code>
permits several modifiers
that control transaction characteristics. To specify multiple
modifiers, separate them by commas.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<code class="literal">
WITH CONSISTENT SNAPSHOT
</code>
modifier
starts a
<a class="link" href="glossary.html#glos_consistent_read" title="consistent read">
consistent
read
</a>
for storage engines that are capable of it. This
applies only to
<code class="literal">
InnoDB
</code>
. The effect is the
same as issuing a
<code class="literal">
START TRANSACTION
</code>
followed by a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
from any
<code class="literal">
InnoDB
</code>
table. See
<a class="xref" href="innodb-consistent-read.html" title="17.7.2.3 Consistent Nonlocking Reads">
Section 17.7.2.3, “Consistent Nonlocking Reads”
</a>
. The
<code class="literal">
WITH
CONSISTENT SNAPSHOT
</code>
modifier does not change the
current transaction
<a class="link" href="glossary.html#glos_isolation_level" title="isolation level">
isolation level
</a>
,
so it provides a consistent snapshot only if the current
isolation level is one that permits a consistent read. The
only isolation level that permits a consistent read is
<a class="link" href="innodb-transaction-isolation-levels.html#isolevel_repeatable-read">
<code class="literal">
REPEATABLE READ
</code>
</a>
. For all
other isolation levels, the
<code class="literal">
WITH CONSISTENT
SNAPSHOT
</code>
clause is ignored. A warning is generated
when the
<code class="literal">
WITH CONSISTENT SNAPSHOT
</code>
clause is
ignored.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
READ WRITE
</code>
and
<code class="literal">
READ
ONLY
</code>
modifiers set the transaction access mode. They
permit or prohibit changes to tables used in the transaction.
The
<code class="literal">
READ ONLY
</code>
restriction prevents the
transaction from modifying or locking both transactional and
nontransactional tables that are visible to other
transactions; the transaction can still modify or lock
temporary tables.
</p>
<p>
MySQL enables extra optimizations for queries on
<code class="literal">
InnoDB
</code>
tables when the transaction is known
to be read-only. Specifying
<code class="literal">
READ ONLY
</code>
ensures these optimizations are applied in cases where the
read-only status cannot be determined automatically. See
<a class="xref" href="innodb-performance-ro-txn.html" title="10.5.3 Optimizing InnoDB Read-Only Transactions">
Section 10.5.3, “Optimizing InnoDB Read-Only Transactions”
</a>
for more
information.
</p>
<p>
If no access mode is specified, the default mode applies.
Unless the default has been changed, it is read/write. It is
not permitted to specify both
<code class="literal">
READ WRITE
</code>
and
<code class="literal">
READ ONLY
</code>
in the same statement.
</p>
<p>
In read-only mode, it remains possible to change tables
created with the
<code class="literal">
TEMPORARY
</code>
keyword using
DML statements. Changes made with DDL statements are not
permitted, just as with permanent tables.
</p>
<p>
For additional information about transaction access mode,
including ways to change the default mode, see
<a class="xref" href="set-transaction.html" title="15.3.7 SET TRANSACTION Statement">
Section 15.3.7, “SET TRANSACTION Statement”
</a>
.
</p>
<p>
If the
<a class="link" href="server-system-variables.html#sysvar_read_only">
<code class="literal">
read_only
</code>
</a>
system
variable is enabled, explicitly starting a transaction with
<code class="literal">
START TRANSACTION READ WRITE
</code>
requires the
<a class="link" href="privileges-provided.html#priv_connection-admin">
<code class="literal">
CONNECTION_ADMIN
</code>
</a>
privilege (or
the deprecated
<a class="link" href="privileges-provided.html#priv_super">
<code class="literal">
SUPER
</code>
</a>
privilege).
</p>
</li>
</ul>
</div>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
Many APIs used for writing MySQL client applications (such as
JDBC) provide their own methods for starting transactions that
can (and sometimes should) be used instead of sending a
<code class="literal">
START TRANSACTION
</code>
statement from the client.
See
<a class="xref" href="connectors-apis.html" title="Chapter 31 Connectors and APIs">
Chapter 31,
<i>
Connectors and APIs
</i>
</a>
, or the documentation for
your API, for more information.
</p>
</div>
<p>
To disable autocommit mode explicitly, use the following
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa56519399"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> autocommit<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
After disabling autocommit mode by setting the
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
variable to zero,
changes to transaction-safe tables (such as those for
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
or
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
) are not made permanent
immediately. You must use
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
to
store your changes to disk or
<code class="literal">
ROLLBACK
</code>
to
ignore the changes.
</p>
<p>
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
is a session variable
and must be set for each session. To disable autocommit mode for
each new connection, see the description of the
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
system variable at
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
.
</p>
<p>
<code class="literal">
BEGIN
</code>
and
<code class="literal">
BEGIN WORK
</code>
are
supported as aliases of
<code class="literal">
START TRANSACTION
</code>
for
initiating a transaction.
<code class="literal">
START TRANSACTION
</code>
is
standard SQL syntax, is the recommended way to start an ad-hoc
transaction, and permits modifiers that
<code class="literal">
BEGIN
</code>
does not.
</p>
<p>
The
<code class="literal">
BEGIN
</code>
statement differs from the use of the
<code class="literal">
BEGIN
</code>
keyword that starts a
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ... END
</code>
</a>
compound statement. The latter does not begin a transaction. See
<a class="xref" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
Section 15.6.1, “BEGIN ... END Compound Statement”
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Within all stored programs (stored procedures and functions,
triggers, and events), the parser treats
<code class="literal">
BEGIN
[WORK]
</code>
as the beginning of a
<a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement">
<code class="literal">
BEGIN ...
END
</code>
</a>
block. Begin a transaction in this context with
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
START
TRANSACTION
</code>
</a>
instead.
</p>
</div>
<p>
The optional
<code class="literal">
WORK
</code>
keyword is supported for
<code class="literal">
COMMIT
</code>
and
<code class="literal">
ROLLBACK
</code>
, as are
the
<code class="literal">
CHAIN
</code>
and
<code class="literal">
RELEASE
</code>
clauses.
<code class="literal">
CHAIN
</code>
and
<code class="literal">
RELEASE
</code>
can be used for additional control over transaction completion.
The value of the
<a class="link" href="server-system-variables.html#sysvar_completion_type">
<code class="literal">
completion_type
</code>
</a>
system variable determines the default completion behavior. See
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
.
</p>
<p>
The
<code class="literal">
AND CHAIN
</code>
clause causes a new transaction
to begin as soon as the current one ends, and the new transaction
has the same isolation level as the just-terminated transaction.
The new transaction also uses the same access mode (
<code class="literal">
READ
WRITE
</code>
or
<code class="literal">
READ ONLY
</code>
) as the
just-terminated transaction. The
<code class="literal">
RELEASE
</code>
clause
causes the server to disconnect the current client session after
terminating the current transaction. Including the
<code class="literal">
NO
</code>
keyword suppresses
<code class="literal">
CHAIN
</code>
or
<code class="literal">
RELEASE
</code>
completion, which can be useful if
the
<a class="link" href="server-system-variables.html#sysvar_completion_type">
<code class="literal">
completion_type
</code>
</a>
system
variable is set to cause chaining or release completion by
default.
</p>
<p>
Beginning a transaction causes any pending transaction to be
committed. See
<a class="xref" href="implicit-commit.html" title="15.3.3 Statements That Cause an Implicit Commit">
Section 15.3.3, “Statements That Cause an Implicit Commit”
</a>
, for more
information.
</p>
<p>
Beginning a transaction also causes table locks acquired with
<a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements">
<code class="literal">
LOCK TABLES
</code>
</a>
to be released, as
though you had executed
<a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements">
<code class="literal">
UNLOCK
TABLES
</code>
</a>
. Beginning a transaction does not release a
global read lock acquired with
<a class="link" href="flush.html#flush-tables-with-read-lock">
<code class="literal">
FLUSH TABLES
WITH READ LOCK
</code>
</a>
.
</p>
<p>
For best results, transactions should be performed using only
tables managed by a single transaction-safe storage engine.
Otherwise, the following problems can occur:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If you use tables from more than one transaction-safe storage
engine (such as
<code class="literal">
InnoDB
</code>
), and the
transaction isolation level is not
<a class="link" href="innodb-transaction-isolation-levels.html#isolevel_serializable">
<code class="literal">
SERIALIZABLE
</code>
</a>
, it is
possible that when one transaction commits, another ongoing
transaction that uses the same tables sees only some of the
changes made by the first transaction. That is, the atomicity
of transactions is not guaranteed with mixed engines and
inconsistencies can result. (If mixed-engine transactions are
infrequent, you can use
<a class="link" href="set-transaction.html" title="15.3.7 SET TRANSACTION Statement">
<code class="literal">
SET
TRANSACTION ISOLATION LEVEL
</code>
</a>
to set the isolation
level to
<a class="link" href="innodb-transaction-isolation-levels.html#isolevel_serializable">
<code class="literal">
SERIALIZABLE
</code>
</a>
on a
per-transaction basis as necessary.)
</p>
</li>
<li class="listitem">
<p>
If you use tables that are not transaction-safe within a
transaction, changes to those tables are stored at once,
regardless of the status of autocommit mode.
</p>
</li>
<li class="listitem">
<p>
If you issue a
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement after updating a nontransactional table within a
transaction, an
<a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_warning_not_complete_rollback" target="_top">
<code class="literal">
ER_WARNING_NOT_COMPLETE_ROLLBACK
</code>
</a>
warning occurs. Changes to transaction-safe tables are rolled
back, but not changes to nontransaction-safe tables.
</p>
</li>
</ul>
</div>
<p>
Each transaction is stored in the binary log in one chunk, upon
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
. Transactions that are
rolled back are not logged.
(
<span class="bold">
<strong>
Exception
</strong>
</span>
: Modifications to
nontransactional tables cannot be rolled back. If a transaction
that is rolled back includes modifications to nontransactional
tables, the entire transaction is logged with a
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement at the end to ensure that modifications to the
nontransactional tables are replicated.) See
<a class="xref" href="binary-log.html" title="7.4.4 The Binary Log">
Section 7.4.4, “The Binary Log”
</a>
.
</p>
<p>
You can change the isolation level or access mode for transactions
with the
<a class="link" href="set-transaction.html" title="15.3.7 SET TRANSACTION Statement">
<code class="literal">
SET TRANSACTION
</code>
</a>
statement.
See
<a class="xref" href="set-transaction.html" title="15.3.7 SET TRANSACTION Statement">
Section 15.3.7, “SET TRANSACTION Statement”
</a>
.
</p>
<p>
Rolling back can be a slow operation that may occur implicitly
without the user having explicitly asked for it (for example, when
an error occurs). Because of this,
<a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement">
<code class="literal">
SHOW
PROCESSLIST
</code>
</a>
displays
<code class="literal">
Rolling back
</code>
in
the
<code class="literal">
State
</code>
column for the session, not only for
explicit rollbacks performed with the
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement but also for implicit rollbacks.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
In MySQL 8.4,
<code class="literal">
BEGIN
</code>
,
<code class="literal">
COMMIT
</code>
, and
<code class="literal">
ROLLBACK
</code>
are
not affected by
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-do-db">
<code class="option">
--replicate-do-db
</code>
</a>
or
<a class="link" href="replication-options-replica.html#option_mysqld_replicate-ignore-db">
<code class="option">
--replicate-ignore-db
</code>
</a>
rules.
</p>
</div>
<p>
When
<code class="literal">
InnoDB
</code>
performs a complete rollback of a
transaction, all locks set by the transaction are released. If a
single SQL statement within a transaction rolls back as a result
of an error, such as a duplicate key error, locks set by the
statement are preserved while the transaction remains active. This
happens because
<code class="literal">
InnoDB
</code>
stores row locks in a
format such that it cannot know afterward which lock was set by
which statement.
</p>
<p>
If a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement within a
transaction calls a stored function, and a statement within the
stored function fails, that statement rolls back. If
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
is
executed for the transaction subsequently, the entire transaction
rolls back.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-shell-tutorial-javascript-indexes-create.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-shell-tutorial-javascript-indexes-create">
</a>
22.3.3.6 Create and Drop Indexes
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127697072">
</a>
<p>
Indexes are used to find documents with specific field values
quickly. Without an index, MySQL must begin with the first
document and then read through the entire collection to find the
relevant fields. The larger the collection, the more this costs.
If a collection is large and queries on a specific field are
common, then consider creating an index on a specific field
inside a document.
</p>
<p>
For example, the following query performs better with an index
on the Population field:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa66594160"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-js></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token string">"demographics.Population < 100"</span><span class="token punctuation">)</span>
<span class="token operator">...</span><span class="token punctuation">[</span><em>output removed</em><span class="token punctuation">]</span>
<span class="token output">8 documents in set (0.00 sec)</span></code></pre>
</div>
<p>
The
<code class="literal">
createIndex()
</code>
method creates an index
that you can define with a JSON document that specifies which
fields to use. This section is a high level overview of
indexing. For more information see
<a class="ulink" href="/doc/x-devapi-userguide/en/collection-indexing.html" target="_top">
Indexing Collections
</a>
.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="mysql-shell-tutorial-javascript-nonunique-index">
</a>
Add a Nonunique Index
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127688656">
</a>
<p>
To create a nonunique index, pass an index name and the index
information to the
<code class="literal">
createIndex()
</code>
method.
Duplicate index names are prohibited.
</p>
<p>
The following example specifies an index named
<code class="literal">
popul
</code>
, defined against the
<code class="literal">
Population
</code>
field from the
<code class="literal">
demographics
</code>
object, indexed as an
<code class="literal">
Integer
</code>
numeric value. The final parameter
indicates whether the field should require the
<code class="literal">
NOT
NULL
</code>
constraint. If the value is
<code class="literal">
false
</code>
, the field can contain
<code class="literal">
NULL
</code>
values. The index information is a
JSON document with details of one or more fields to include in
the index. Each field definition must include the full
document path to the field, and specify the type of the field.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa46266648"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-js></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">createIndex</span><span class="token punctuation">(</span><span class="token string">"popul"</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>fields<span class="token punctuation">:</span>
<span class="token punctuation">[</span><span class="token punctuation">{</span>field<span class="token punctuation">:</span> <span class="token string">'$.demographics.Population'</span><span class="token punctuation">,</span> type<span class="token punctuation">:</span> <span class="token string">'INTEGER'</span><span class="token punctuation">}</span><span class="token punctuation">]</span><span class="token punctuation">}</span><span class="token punctuation">)</span></code></pre>
</div>
<p>
Here, the index is created using an integer numeric value.
Further options are available, including options for use with
GeoJSON data. You can also specify the type of index, which
has been omitted here because the default type
<span class="quote">
“
<span class="quote">
index
</span>
”
</span>
is appropriate.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="mysql-shell-tutorial-javascript-unique-index">
</a>
Add a Unique Index
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127675840">
</a>
<p>
To create a unique index, pass an index name, the index
definition, and the index type
<span class="quote">
“
<span class="quote">
unique
</span>
”
</span>
to the
<code class="literal">
createIndex()
</code>
method. This example shows a
unique index created on the country name
(
<code class="literal">
"Name"
</code>
), which is another common field in
the
<code class="literal">
countryinfo
</code>
collection to index. In the
index field description,
<code class="literal">
"TEXT(40)"
</code>
represents the number of characters to index, and
<code class="literal">
"required": True
</code>
specifies that the field
is required to exist in the document.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-mysqlsh"><div class="docs-select-all right" id="sa61440734"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-js></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">createIndex</span><span class="token punctuation">(</span><span class="token string">"name"</span><span class="token punctuation">,</span>
<span class="token punctuation">{</span><span class="token string">"fields"</span><span class="token punctuation">:</span> <span class="token punctuation">[</span><span class="token punctuation">{</span><span class="token string">"field"</span><span class="token punctuation">:</span> <span class="token string">"$.Name"</span><span class="token punctuation">,</span> <span class="token string">"type"</span><span class="token punctuation">:</span> <span class="token string">"TEXT(40)"</span><span class="token punctuation">,</span> <span class="token string">"required"</span><span class="token punctuation">:</span> <span class="token boolean">true</span><span class="token punctuation">}</span><span class="token punctuation">]</span><span class="token punctuation">,</span> <span class="token string">"unique"</span><span class="token punctuation">:</span> <span class="token boolean">true</span><span class="token punctuation">}</span><span class="token punctuation">)</span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="mysql-shell-tutorial-javascript-drop-index">
</a>
Drop an Index
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045127666464">
</a>
<p>
To drop an index, pass the name of the index to drop to the
<code class="literal">
dropIndex()
</code>
method. For example, you can
drop the
<span class="quote">
“
<span class="quote">
popul
</span>
”
</span>
index as follows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-mysqlsh"><div class="docs-select-all right" id="sa95811214"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-mysqlsh"><span class="token prompt">mysql-js></span> db<span class="token punctuation">.</span>countryinfo<span class="token punctuation">.</span><span class="token function">dropIndex</span><span class="token punctuation">(</span><span class="token string">"popul"</span><span class="token punctuation">)</span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="idm46045127661536">
</a>
Related Information
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
See
<a class="ulink" href="/doc/x-devapi-userguide/en/collection-indexing.html" target="_top">
Indexing Collections
</a>
for more
information.
</p>
</li>
<li class="listitem">
<p>
See
<a class="ulink" href="/doc/x-devapi-userguide/en/collection-indexing.html#collection-index-definitions" target="_top">
Defining an Index
</a>
for
more information on the JSON document that defines an
index.
</p>
</li>
<li class="listitem">
<p>
See
<a class="ulink" href="/doc/x-devapi-userguide/en/crud-ebnf-collection-index-management-functions.html" target="_top">
Collection Index Management Functions
</a>
for the full syntax definition.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/clone-plugin-stop.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="clone-plugin-stop">
</a>
7.6.7.11 Stopping a Cloning Operation
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045255144144">
</a>
<p>
If necessary, you can stop a cloning operation with a
<a class="link" href="kill.html" title="15.7.8.4 KILL Statement">
<code class="literal">
KILL QUERY
<em class="replaceable">
<code>
processlist_id
</code>
</em>
</code>
</a>
statement.
</p>
<p>
On the recipient MySQL server instance, you can retrieve the
processlist identifier (PID) for a cloning operation from the
<code class="literal">
PID
</code>
column of the
<a class="link" href="performance-schema-clone-status-table.html" title="29.12.19.1 The clone_status Table">
<code class="literal">
clone_status
</code>
</a>
table.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa45633329"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>clone_status\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
ID<span class="token punctuation">:</span> 1
PID<span class="token punctuation">:</span> 8
STATE<span class="token punctuation">:</span> In Progress
BEGIN_TIME<span class="token punctuation">:</span> 2019-07-15 11<span class="token punctuation">:</span>58<span class="token punctuation">:</span>36.767
END_TIME<span class="token punctuation">:</span> NULL
SOURCE<span class="token punctuation">:</span> LOCAL INSTANCE
DESTINATION<span class="token punctuation">:</span> /<em class="replaceable">path/to/clone_dir</em>/
ERROR_NO<span class="token punctuation">:</span> 0
ERROR_MESSAGE<span class="token punctuation">:</span>
BINLOG_FILE<span class="token punctuation">:</span>
BINLOG_POSITION<span class="token punctuation">:</span> 0
GTID_EXECUTED<span class="token punctuation">:</span></span></code></pre>
</div>
<p>
You can also retrieve the processlist identifier from the
<code class="literal">
ID
</code>
column of the
<code class="literal">
INFORMATION_SCHEMA
</code>
<a class="link" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table">
<code class="literal">
PROCESSLIST
</code>
</a>
table, the
<code class="literal">
Id
</code>
column of
<a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement">
<code class="literal">
SHOW
PROCESSLIST
</code>
</a>
output, or the
<code class="literal">
PROCESSLIST_ID
</code>
column of the Performance
Schema
<a class="link" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table">
<code class="literal">
threads
</code>
</a>
table. These methods
of obtaining the PID information can be used on the donor or
recipient MySQL server instance.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-interconnects.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="mysql-cluster-interconnects">
</a>
25.4.4 Using High-Speed Interconnects with NDB Cluster
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045108508352">
</a>
<a class="indexterm" name="idm46045108506864">
</a>
<a class="indexterm" name="idm46045108505376">
</a>
<a class="indexterm" name="idm46045108504272">
</a>
<p>
Even before design of
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDBCLUSTER
</code>
</a>
began in 1996, it was evident that one of the major problems to be
encountered in building parallel databases would be communication
between the nodes in the network. For this reason,
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDBCLUSTER
</code>
</a>
was designed from the very
beginning to permit the use of a number of different data
transport mechanisms, or transporters.
</p>
<p>
NDB Cluster supports three of these (see
<a class="xref" href="mysql-cluster-basics.html" title="25.2.1 NDB Cluster Core Concepts">
Section 25.2.1, “NDB Cluster Core Concepts”
</a>
). A fourth transporter,
Scalable Coherent Interface (SCI), was also supported in very old
versions of
<code class="literal">
NDB
</code>
. This required specialized
hardware, software, and MySQL binaries that are no longer
available.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/subquery-restrictions.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="subquery-restrictions">
</a>
15.2.15.12 Restrictions on Subqueries
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045179608400">
</a>
<a class="indexterm" name="idm46045179606944">
</a>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
In general, you cannot modify a table and select from the
same table in a subquery. For example, this limitation
applies to statements of the following forms:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa53312231"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">DELETE</span> <span class="token keyword">FROM</span> t <span class="token keyword">WHERE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">FROM</span> t <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">UPDATE</span> t <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WHERE</span> col <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">FROM</span> t <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
{<span class="token keyword">INSERT</span><span class="token operator">|</span><span class="token keyword">REPLACE</span>} <span class="token keyword">INTO</span> t <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">FROM</span> t <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Exception: The preceding prohibition does not apply if for
the modified table you are using a derived table and that
derived table is materialized rather than merged into the
outer query. (See
<a class="xref" href="derived-table-optimization.html" title="10.2.2.4 Optimizing Derived Tables, View References, and Common Table Expressions with Merging or Materialization">
Section 10.2.2.4, “Optimizing Derived Tables, View References, and Common Table Expressions
with Merging or Materialization”
</a>
.) Example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa1400521"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> t <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WHERE</span> col <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">FROM</span> t<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> dt <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Here the result from the derived table is materialized as a
temporary table, so the relevant rows in
<code class="literal">
t
</code>
have already been selected by the time
the update to
<code class="literal">
t
</code>
takes place.
</p>
<p>
In general, you may be able to influence the optimizer to
materialize a derived table by adding a
<a class="link" href="optimizer-hints.html#optimizer-hints-table-level" title="Table-Level Optimizer Hints">
<code class="literal">
NO_MERGE
</code>
</a>
optimizer hint.
See
<a class="xref" href="optimizer-hints.html" title="10.9.3 Optimizer Hints">
Section 10.9.3, “Optimizer Hints”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Row comparison operations are only partially supported:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
For
<code class="literal">
<em class="replaceable">
<code>
expr
</code>
</em>
[NOT] IN
<em class="replaceable">
<code>
subquery
</code>
</em>
</code>
,
<em class="replaceable">
<code>
expr
</code>
</em>
can be an
<em class="replaceable">
<code>
n
</code>
</em>
-tuple (specified using row
constructor syntax) and the subquery can return rows of
<em class="replaceable">
<code>
n
</code>
</em>
-tuples. The permitted
syntax is therefore more specifically expressed as
<code class="literal">
<em class="replaceable">
<code>
row_constructor
</code>
</em>
[NOT] IN
<em class="replaceable">
<code>
table_subquery
</code>
</em>
</code>
</p>
</li>
<li class="listitem">
<p>
For
<code class="literal">
<em class="replaceable">
<code>
expr
</code>
</em>
<em class="replaceable">
<code>
op
</code>
</em>
{ALL|ANY|SOME}
<em class="replaceable">
<code>
subquery
</code>
</em>
</code>
,
<em class="replaceable">
<code>
expr
</code>
</em>
must be a scalar value
and the subquery must be a column subquery; it cannot
return multiple-column rows.
</p>
</li>
</ul>
</div>
<p>
In other words, for a subquery that returns rows of
<em class="replaceable">
<code>
n
</code>
</em>
-tuples, this is supported:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa58957960"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span><em class="replaceable">expr_1</em><span class="token punctuation">,</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">,</span> <em class="replaceable">expr_n</em><span class="token punctuation">)</span> <span class="token punctuation">[</span><span class="token operator">NOT</span><span class="token punctuation">]</span> <span class="token keyword">IN</span> <em class="replaceable">table_subquery</em></code></pre>
</div>
<p>
But this is not supported:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa4070993"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span><em class="replaceable">expr_1</em><span class="token punctuation">,</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">,</span> <em class="replaceable">expr_n</em><span class="token punctuation">)</span> <em class="replaceable">op</em> {<span class="token keyword">ALL</span><span class="token operator">|</span><span class="token keyword">ANY</span><span class="token operator">|</span><span class="token keyword">SOME</span>} <em class="replaceable">subquery</em></code></pre>
</div>
<p>
The reason for supporting row comparisons for
<code class="literal">
IN
</code>
but not for the others is that
<code class="literal">
IN
</code>
is implemented by rewriting it as a
sequence of
<a class="link" href="comparison-operators.html#operator_equal">
<code class="literal">
=
</code>
</a>
comparisons and
<a class="link" href="logical-operators.html#operator_and">
<code class="literal">
AND
</code>
</a>
operations.
This approach cannot be used for
<code class="literal">
ALL
</code>
,
<code class="literal">
ANY
</code>
, or
<code class="literal">
SOME
</code>
.
</p>
</li>
<li class="listitem">
<p>
MySQL does not support
<code class="literal">
LIMIT
</code>
in
subqueries for certain subquery operators:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa93192166"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1
<span class="token keyword">WHERE</span> s1 <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> s2 <span class="token keyword">FROM</span> t2 <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> s1 <span class="token keyword">LIMIT</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1235 (42000)<span class="token punctuation">:</span> This version of MySQL doesn't yet support
'LIMIT & IN/ALL/ANY/SOME subquery'</span></code></pre>
</div>
<p>
See
<a class="xref" href="subquery-errors.html" title="15.2.15.10 Subquery Errors">
Section 15.2.15.10, “Subquery Errors”
</a>
.
</p>
</li>
<li class="listitem">
<p>
MySQL permits a subquery to refer to a stored function that
has data-modifying side effects such as inserting rows into
a table. For example, if
<code class="literal">
f()
</code>
inserts
rows, the following query can modify data:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa9320760"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WHERE</span> x <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> f<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This behavior is an extension to the SQL standard. In MySQL,
it can produce nondeterministic results because
<code class="literal">
f()
</code>
might be executed a different number
of times for different executions of a given query depending
on how the optimizer chooses to handle it.
</p>
<p>
For statement-based or mixed-format replication, one
implication of this indeterminism is that such a query can
produce different results on the source and its replicas.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/using-systemd.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="using-systemd">
</a>
2.5.9 Managing MySQL Server with systemd
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045330029040">
</a>
<p>
If you install MySQL using an RPM or Debian package on the
following Linux platforms, server startup and shutdown is managed
by systemd:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
RPM package platforms:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Enterprise Linux variants version 7 and higher
</p>
</li>
<li class="listitem">
<p>
SUSE Linux Enterprise Server 12 and higher
</p>
</li>
<li class="listitem">
<p>
Fedora 29 and higher
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Debian family platforms:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Debian platforms
</p>
</li>
<li class="listitem">
<p>
Ubuntu platforms
</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<p>
If you install MySQL from a generic binary distribution on a
platform that uses systemd, you can manually configure systemd
support for MySQL following the instructions provided in the
post-installation setup section of the
<a class="ulink" href="/doc/mysql-secure-deployment-guide/en/" target="_top">
MySQL
8.4 Secure Deployment Guide
</a>
.
</p>
<p>
If you install MySQL from a source distribution on a platform that
uses systemd, obtain systemd support for MySQL by configuring the
distribution using the
<a class="link" href="source-configuration-options.html#option_cmake_with_systemd">
<code class="option">
-DWITH_SYSTEMD=1
</code>
</a>
<span class="command">
<strong>
CMake
</strong>
</span>
option. See
<a class="xref" href="source-configuration-options.html" title="2.8.7 MySQL Source-Configuration Options">
Section 2.8.7, “MySQL Source-Configuration Options”
</a>
.
</p>
<p>
The following discussion covers these topics:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="using-systemd.html#systemd-overview" title="Overview of systemd">
Overview of systemd
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="using-systemd.html#systemd-mysql-configuration" title="Configuring systemd for MySQL">
Configuring systemd for MySQL
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="using-systemd.html#systemd-multiple-mysql-instances" title="Configuring Multiple MySQL Instances Using systemd">
Configuring Multiple MySQL Instances Using systemd
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="using-systemd.html#mysqld-safe-to-systemd-migration" title="Migrating from mysqld_safe to systemd">
Migrating from mysqld_safe to systemd
</a>
</p>
</li>
</ul>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
On platforms for which systemd support for MySQL is installed,
scripts such as
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
and the System V
initialization script are unnecessary and are not installed. For
example,
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
can handle server
restarts, but systemd provides the same capability, and does so
in a manner consistent with management of other services rather
than by using an application-specific program.
</p>
<p>
One implication of the non-use of
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
on platforms that use systemd for server management is that use
of
<code class="literal">
[mysqld_safe]
</code>
or
<code class="literal">
[safe_mysqld]
</code>
sections in option files is not
supported and might lead to unexpected behavior.
</p>
<p>
Because systemd has the capability of managing multiple MySQL
instances on platforms for which systemd support for MySQL is
installed,
<a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers">
<span class="command">
<strong>
mysqld_multi
</strong>
</span>
</a>
and
<span class="command">
<strong>
mysqld_multi.server
</strong>
</span>
are unnecessary and are
not installed.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="systemd-overview">
</a>
Overview of systemd
</h4>
</div>
</div>
</div>
<p>
systemd provides automatic MySQL server startup and shutdown. It
also enables manual server management using the
<span class="command">
<strong>
systemctl
</strong>
</span>
command. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa80766534"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">systemctl</span> <span class="token punctuation"></span><em class="replaceable"><span class="token punctuation">{</span>start|stop|restart|status<span class="token punctuation">}</span></em><span class="token punctuation"></span> mysqld</code></pre>
</div>
<p>
Alternatively, use the
<span class="command">
<strong>
service
</strong>
</span>
command (with
the arguments reversed), which is compatible with System V
systems:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa65971275"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">service</span> mysqld <span class="token punctuation"></span><em class="replaceable"><span class="token punctuation">{</span>start|stop|restart|status<span class="token punctuation">}</span></em><span class="token punctuation"></span></code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
For the
<span class="command">
<strong>
systemctl
</strong>
</span>
command (and the
alternative
<span class="command">
<strong>
service
</strong>
</span>
command), if the MySQL
service name is not
<code class="literal">
mysqld
</code>
then use the
appropriate name. For example, use
<code class="literal">
mysql
</code>
rather than
<code class="literal">
mysqld
</code>
on Debian-based and SLES
systems.
</p>
</div>
<p>
Support for systemd includes these files:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="filename">
mysqld.service
</code>
(RPM platforms),
<code class="filename">
mysql.service
</code>
(Debian platforms):
systemd service unit configuration file, with details about
the MySQL service.
</p>
</li>
<li class="listitem">
<p>
<code class="filename">
[email protected]
</code>
(RPM platforms),
<code class="filename">
[email protected]
</code>
(Debian platforms): Like
<code class="filename">
mysqld.service
</code>
or
<code class="filename">
mysql.service
</code>
, but used for managing
multiple MySQL instances.
</p>
</li>
<li class="listitem">
<p>
<code class="filename">
mysqld.tmpfiles.d
</code>
: File containing
information to support the
<code class="literal">
tmpfiles
</code>
feature. This file is installed under the name
<code class="filename">
mysql.conf
</code>
.
</p>
</li>
<li class="listitem">
<p>
<code class="filename">
mysqld_pre_systemd
</code>
(RPM platforms),
<code class="filename">
mysql-system-start
</code>
(Debian platforms):
Support script for the unit file. This script assists in
creating the error log file only if the log location matches
a pattern (
<code class="literal">
/var/log/mysql*.log
</code>
for RPM
platforms,
<code class="literal">
/var/log/mysql/*.log
</code>
for
Debian platforms). In other cases, the error log directory
must be writable or the error log must be present and
writable for the user running the
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
process.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="systemd-mysql-configuration">
</a>
Configuring systemd for MySQL
</h4>
</div>
</div>
</div>
<p>
To add or change systemd options for MySQL, these methods are
available:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Use a localized systemd configuration file.
</p>
</li>
<li class="listitem">
<p>
Arrange for systemd to set environment variables for the
MySQL server process.
</p>
</li>
<li class="listitem">
<p>
Set the
<code class="literal">
MYSQLD_OPTS
</code>
systemd variable.
</p>
</li>
</ul>
</div>
<p>
To use a localized systemd configuration file, create the
<code class="filename">
/etc/systemd/system/mysqld.service.d
</code>
directory if it does not exist. In that directory, create a file
that contains a
<code class="literal">
[Service]
</code>
section listing the
desired settings. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa6988269"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[Service]</span>
<span class="token constant">LimitNOFILE</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">max_open_files</em></span>
<span class="token constant">Nice</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">nice_level</em></span>
<span class="token constant">LimitCore</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">core_file_limit</em></span>
<span class="token constant">Environment</span><span class="token attr-value"><span class="token punctuation">=</span>"LD_PRELOAD=<em class="replaceable">/path/to/malloc/library</em>"</span>
<span class="token constant">Environment</span><span class="token attr-value"><span class="token punctuation">=</span>"TZ=<em class="replaceable">time_zone_setting</em>"</span></code></pre>
</div>
<p>
The discussion here uses
<code class="filename">
override.conf
</code>
as
the name of this file. Newer versions of systemd support the
following command, which opens an editor and permits you to edit
the file:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa69581462"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl edit mysqld <span class="token comment" spellcheck="true"># RPM platforms</span>
systemctl edit mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre>
</div>
<p>
Whenever you create or change
<code class="filename">
override.conf
</code>
, reload the systemd
configuration, then tell systemd to restart the MySQL service:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa6847939"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl daemon-reload
systemctl restart mysqld <span class="token comment" spellcheck="true"># RPM platforms</span>
systemctl restart mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre>
</div>
<p>
With systemd, the
<code class="filename">
override.conf
</code>
configuration method must be used for certain parameters, rather
than settings in a
<code class="literal">
[mysqld]
</code>
,
<code class="literal">
[mysqld_safe]
</code>
, or
<code class="literal">
[safe_mysqld]
</code>
group in a MySQL option file:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
For some parameters,
<code class="filename">
override.conf
</code>
must
be used because systemd itself must know their values and it
cannot read MySQL option files to get them.
</p>
</li>
<li class="listitem">
<p>
Parameters that specify values otherwise settable only using
options known to
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
must be
specified using systemd because there is no corresponding
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
parameter.
</p>
</li>
</ul>
</div>
<p>
For additional information about using systemd rather than
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
, see
<a class="xref" href="using-systemd.html#mysqld-safe-to-systemd-migration" title="Migrating from mysqld_safe to systemd">
Migrating from mysqld_safe to systemd
</a>
.
</p>
<p>
You can set the following parameters in
<code class="filename">
override.conf
</code>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
To set the number of file descriptors available to the MySQL
server, use
<code class="literal">
LimitNOFILE
</code>
in
<code class="filename">
override.conf
</code>
rather than the
<a class="link" href="server-system-variables.html#sysvar_open_files_limit">
<code class="literal">
open_files_limit
</code>
</a>
system
variable for
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
or
<a class="link" href="mysqld-safe.html#option_mysqld_safe_open-files-limit">
<code class="option">
--open-files-limit
</code>
</a>
option for
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
.
</p>
</li>
<li class="listitem">
<p>
To set the maximum core file size, use
<code class="literal">
LimitCore
</code>
in
<code class="filename">
override.conf
</code>
rather than the
<a class="link" href="mysqld-safe.html#option_mysqld_safe_core-file-size">
<code class="option">
--core-file-size
</code>
</a>
option
for
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
.
</p>
</li>
<li class="listitem">
<p>
To set the scheduling priority for the MySQL server, use
<code class="literal">
Nice
</code>
in
<code class="filename">
override.conf
</code>
rather than the
<a class="link" href="mysqld-safe.html#option_mysqld_safe_nice">
<code class="option">
--nice
</code>
</a>
option for
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
.
</p>
</li>
</ul>
</div>
<p>
Some MySQL parameters are configured using environment
variables:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
LD_PRELOAD
</code>
: Set this variable if the
MySQL server should use a specific memory-allocation
library.
</p>
<a class="indexterm" name="idm46045329925536">
</a>
<a class="indexterm" name="idm46045329924448">
</a>
<a class="indexterm" name="idm46045329923360">
</a>
</li>
<li class="listitem">
<p>
<code class="literal">
NOTIFY_SOCKET
</code>
: This environment variable
specifies the socket that
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
uses to
communicate notification of startup completion and service
status change with systemd. It is set by systemd when the
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
service is started. The
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
service reads the variable setting
and writes to the defined location.
</p>
<p>
In MySQL 8.4,
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
uses
the
<code class="literal">
Type=notify
</code>
process startup type.
(
<code class="literal">
Type=forking
</code>
was used in MySQL 5.7.)
With
<code class="literal">
Type=notify
</code>
, systemd automatically
configures a socket file and exports the path to the
<code class="literal">
NOTIFY_SOCKET
</code>
environment variable.
</p>
<a class="indexterm" name="idm46045329911712">
</a>
<a class="indexterm" name="idm46045329910624">
</a>
</li>
<li class="listitem">
<p>
<code class="literal">
TZ
</code>
: Set this variable to specify the
default time zone for the server.
</p>
<a class="indexterm" name="idm46045329907552">
</a>
<a class="indexterm" name="idm46045329906480">
</a>
</li>
</ul>
</div>
<p>
There are multiple ways to specify environment variable values
for use by the MySQL server process managed by systemd:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Use
<code class="literal">
Environment
</code>
lines in the
<code class="filename">
override.conf
</code>
file. For the syntax, see
the example in the preceding discussion that describes how
to use this file.
</p>
</li>
<li class="listitem">
<p>
Specify the values in the
<code class="filename">
/etc/sysconfig/mysql
</code>
file (create the
file if it does not exist). Assign values using the
following syntax:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa19923837"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">LD_PRELOAD</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">/path/to/malloc/library</em></span>
<span class="token constant">TZ</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">time_zone_setting</em></span></code></pre>
</div>
<p>
After modifying
<code class="filename">
/etc/sysconfig/mysql
</code>
,
restart the server to make the changes effective:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa59128878"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl restart mysqld <span class="token comment" spellcheck="true"># RPM platforms</span>
systemctl restart mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre>
</div>
</li>
</ul>
</div>
<a class="indexterm" name="idm46045329895760">
</a>
<a class="indexterm" name="idm46045329894672">
</a>
<p>
To specify options for
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
without
modifying systemd configuration files directly, set or unset the
<code class="literal">
MYSQLD_OPTS
</code>
systemd variable. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa37398088"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl set-environment MYSQLD_OPTS=<span class="token atrule">"--general_log=1"</span>
systemctl unset-environment MYSQLD_OPTS</code></pre>
</div>
<p>
<code class="literal">
MYSQLD_OPTS
</code>
can also be set in the
<code class="filename">
/etc/sysconfig/mysql
</code>
file.
</p>
<p>
After modifying the systemd environment, restart the server to
make the changes effective:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa29932124"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl restart mysqld <span class="token comment" spellcheck="true"># RPM platforms</span>
systemctl restart mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre>
</div>
<p>
For platforms that use systemd, the data directory is
initialized if empty at server startup. This might be a problem
if the data directory is a remote mount that has temporarily
disappeared: The mount point would appear to be an empty data
directory, which then would be initialized as a new data
directory. To suppress this automatic initialization behavior,
specify the following line in the
<code class="filename">
/etc/sysconfig/mysql
</code>
file (create the file
if it does not exist):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa79515182"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">NO_INIT</span><span class="token attr-value"><span class="token punctuation">=</span>true</span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="systemd-multiple-mysql-instances">
</a>
Configuring Multiple MySQL Instances Using systemd
</h4>
</div>
</div>
</div>
<p>
This section describes how to configure systemd for multiple
instances of MySQL.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Because systemd has the capability of managing multiple MySQL
instances on platforms for which systemd support is installed,
<a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers">
<span class="command">
<strong>
mysqld_multi
</strong>
</span>
</a>
and
<span class="command">
<strong>
mysqld_multi.server
</strong>
</span>
are unnecessary and are
not installed.
</p>
</div>
<p>
To use multiple-instance capability, modify the
<code class="filename">
my.cnf
</code>
option file to include configuration
of key options for each instance. These file locations are
typical:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="filename">
/etc/my.cnf
</code>
or
<code class="filename">
/etc/mysql/my.cnf
</code>
(RPM platforms)
</p>
</li>
<li class="listitem">
<p>
<code class="filename">
/etc/mysql/mysql.conf.d/mysqld.cnf
</code>
(Debian platforms)
</p>
</li>
</ul>
</div>
<p>
For example, to manage two instances named
<code class="literal">
replica01
</code>
and
<code class="literal">
replica02
</code>
,
add something like this to the option file:
</p>
<p>
RPM platforms:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa10518130"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld@replica01]</span>
<span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica01</span>
<span class="token constant">socket</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica01/mysql.sock</span>
<span class="token constant">port</span><span class="token attr-value"><span class="token punctuation">=</span>3307</span>
<span class="token constant">log-error</span><span class="token attr-value"><span class="token punctuation">=</span>/var/log/mysqld-replica01.log</span>
<span class="token selector">[mysqld@replica02]</span>
<span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica02</span>
<span class="token constant">socket</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica02/mysql.sock</span>
<span class="token constant">port</span><span class="token attr-value"><span class="token punctuation">=</span>3308</span>
<span class="token constant">log-error</span><span class="token attr-value"><span class="token punctuation">=</span>/var/log/mysqld-replica02.log</span></code></pre>
</div>
<p>
Debian platforms:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa50149803"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld@replica01]</span>
<span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica01</span>
<span class="token constant">socket</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica01/mysql.sock</span>
<span class="token constant">port</span><span class="token attr-value"><span class="token punctuation">=</span>3307</span>
<span class="token constant">log-error</span><span class="token attr-value"><span class="token punctuation">=</span>/var/log/mysql/replica01.log</span>
<span class="token selector">[mysqld@replica02]</span>
<span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica02</span>
<span class="token constant">socket</span><span class="token attr-value"><span class="token punctuation">=</span>/var/lib/mysql-replica02/mysql.sock</span>
<span class="token constant">port</span><span class="token attr-value"><span class="token punctuation">=</span>3308</span>
<span class="token constant">log-error</span><span class="token attr-value"><span class="token punctuation">=</span>/var/log/mysql/replica02.log</span></code></pre>
</div>
<p>
The replica names shown here use
<code class="literal">
@
</code>
as the
delimiter because that is the only delimiter supported by
systemd.
</p>
<p>
Instances then are managed by normal systemd commands, such as:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa70512607"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl start mysqld@replica01
systemctl start mysqld@replica02</code></pre>
</div>
<p>
To enable instances to run at boot time, do this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa28232664"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl enable mysqld@replica01
systemctl enable mysqld@replica02</code></pre>
</div>
<p>
Use of wildcards is also supported. For example, this command
displays the status of all replica instances:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa68916325"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl status <span class="token atrule">'mysqld@replica*'</span></code></pre>
</div>
<p>
For management of multiple MySQL instances on the same machine,
systemd automatically uses a different unit file:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="filename">
[email protected]
</code>
rather than
<code class="filename">
mysqld.service
</code>
(RPM platforms)
</p>
</li>
<li class="listitem">
<p>
<code class="filename">
[email protected]
</code>
rather than
<code class="filename">
mysql.service
</code>
(Debian platforms)
</p>
</li>
</ul>
</div>
<p>
In the unit file,
<code class="literal">
%I
</code>
and
<code class="literal">
%i
</code>
reference the parameter passed in after
the
<code class="literal">
@
</code>
marker and are used to manage the
specific instance. For a command such as this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa91355206"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">systemctl start mysqld@replica01</code></pre>
</div>
<p>
systemd starts the server using a command such as this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa56222235"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld <span class="token constant">--defaults-group-suffix</span><span class="token attr-value"><span class="token punctuation">=</span>@%I</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
The result is that the
<code class="literal">
[server]
</code>
,
<code class="literal">
[mysqld]
</code>
, and
<code class="literal">
[mysqld@replica01]
</code>
option groups are read and
used for that instance of the service.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
On Debian platforms, AppArmor prevents the server from reading
or writing
<code class="filename">
/var/lib/mysql-replica*
</code>
, or
anything other than the default locations. To address this,
you must customize or disable the profile in
<code class="filename">
/etc/apparmor.d/usr.sbin.mysqld
</code>
.
</p>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
On Debian platforms, the packaging scripts for MySQL
uninstallation cannot currently handle
<code class="literal">
mysqld@
</code>
instances. Before removing or
upgrading the package, you must stop any extra instances
manually first.
</p>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="mysqld-safe-to-systemd-migration">
</a>
Migrating from mysqld_safe to systemd
</h4>
</div>
</div>
</div>
<p>
Because
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
is not installed on
platforms that use systemd to manage MySQL, options previously
specified for that program (for example, in an
<code class="literal">
[mysqld_safe]
</code>
or
<code class="literal">
[safe_mysqld]
</code>
option group) must be specified
another way:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Some
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
options are also
understood by
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
and can be moved
from the
<code class="literal">
[mysqld_safe]
</code>
or
<code class="literal">
[safe_mysqld]
</code>
option group to the
<code class="literal">
[mysqld]
</code>
group. This does
<span class="emphasis">
<em>
not
</em>
</span>
include
<a class="link" href="mysqld-safe.html#option_mysqld_safe_pid-file">
<code class="option">
--pid-file
</code>
</a>
,
<a class="link" href="mysqld-safe.html#option_mysqld_safe_open-files-limit">
<code class="option">
--open-files-limit
</code>
</a>
, or
<a class="link" href="mysqld-safe.html#option_mysqld_safe_nice">
<code class="option">
--nice
</code>
</a>
. To specify those
options, use the
<code class="filename">
override.conf
</code>
systemd
file, described previously.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
On systemd platforms, use of
<code class="literal">
[mysqld_safe]
</code>
and
<code class="literal">
[safe_mysqld]
</code>
option groups is not
supported and may lead to unexpected behavior.
</p>
</div>
</li>
<li class="listitem">
<p>
For some
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
options, there are
alternative
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
procedures. For
example, the
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
option for
enabling
<code class="literal">
syslog
</code>
logging is
<a class="link" href="mysqld-safe.html#option_mysqld_safe_syslog">
<code class="option">
--syslog
</code>
</a>
, which is
deprecated. To write error log output to the system log, use
the instructions at
<a class="xref" href="error-log-syslog.html" title="7.4.2.8 Error Logging to the System Log">
Section 7.4.2.8, “Error Logging to the System Log”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
options not understood by
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
can be specified in
<code class="filename">
override.conf
</code>
or environment variables.
For example, with
<a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script">
<span class="command">
<strong>
mysqld_safe
</strong>
</span>
</a>
, if the
server should use a specific memory allocation library, this
is specified using the
<a class="link" href="mysqld-safe.html#option_mysqld_safe_malloc-lib">
<code class="option">
--malloc-lib
</code>
</a>
option. For
installations that manage the server with systemd, arrange
to set the
<code class="literal">
LD_PRELOAD
</code>
environment
variable instead, as described previously.
</p>
</li>
</ul>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sql-utility-statements.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="sql-utility-statements">
</a>
15.8 Utility Statements
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="describe.html">
15.8.1 DESCRIBE Statement
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="explain.html">
15.8.2 EXPLAIN Statement
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="help.html">
15.8.3 HELP Statement
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="use.html">
15.8.4 USE Statement
</a>
</span>
</dt>
</dl>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-clone-tables.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="performance-schema-clone-tables">
</a>
29.12.19 Performance Schema Clone Tables
</h3>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="performance-schema-clone-status-table.html">
29.12.19.1 The clone_status Table
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="performance-schema-clone-progress-table.html">
29.12.19.2 The clone_progress Table
</a>
</span>
</dt>
</dl>
</div>
<p>
The following sections describe the Performance Schema tables
associated with the clone plugin (see
<a class="xref" href="clone-plugin.html" title="7.6.7 The Clone Plugin">
Section 7.6.7, “The Clone Plugin”
</a>
). The tables provide information
about cloning operations.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
clone_status
</code>
: status information about
the current or last executed cloning operation.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
clone_progress
</code>
: progress information
about the current or last executed cloning operation.
</p>
</li>
</ul>
</div>
<p>
The Performance Schema clone tables are implemented by the clone
plugin and are loaded and unloaded when that plugin is loaded
and unloaded (see
<a class="xref" href="clone-plugin-installation.html" title="7.6.7.1 Installing the Clone Plugin">
Section 7.6.7.1, “Installing the Clone Plugin”
</a>
).
No special configuration step for the tables is needed. However,
the tables depend on the clone plugin being enabled. If the
clone plugin is loaded but disabled, the tables are not created.
</p>
<p>
The Performance Schema clone plugin tables are used only on the
recipient MySQL server instance. The data is persisted across
server shutdown and restart.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/information-schema-table-reference.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="information-schema-table-reference">
</a>
28.2 INFORMATION_SCHEMA Table Reference
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045080908816">
</a>
<a class="indexterm" name="idm46045080907328">
</a>
<p>
The following table summarizes all available
<code class="literal">
INFORMATION_SCHEMA
</code>
tables. For greater detail,
see the individual table descriptions.
</p>
<div class="table">
<a name="idm46045080904592">
</a>
<p class="title">
<b>
Table 28.1 INFORMATION_SCHEMA Tables
</b>
</p>
<div class="table-contents">
<table frame="box" rules="all" summary="A reference that lists all INFORMATION_SCHEMA tables.">
<colgroup>
<col style="width: 25%"/>
<col style="width: 62%"/>
<col style="width: 12%"/>
</colgroup>
<thead>
<tr>
<th>
Table Name
</th>
<th>
Description
</th>
<th>
Deprecated
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<a class="link" href="information-schema-administrable-role-authorizations-table.html" title="28.3.2 The INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table">
<code class="literal">
ADMINISTRABLE_ROLE_AUTHORIZATIONS
</code>
</a>
</th>
<td>
Grantable users or roles for current user or role
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-applicable-roles-table.html" title="28.3.3 The INFORMATION_SCHEMA APPLICABLE_ROLES Table">
<code class="literal">
APPLICABLE_ROLES
</code>
</a>
</th>
<td>
Applicable roles for current user
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table">
<code class="literal">
CHARACTER_SETS
</code>
</a>
</th>
<td>
Available character sets
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-check-constraints-table.html" title="28.3.5 The INFORMATION_SCHEMA CHECK_CONSTRAINTS Table">
<code class="literal">
CHECK_CONSTRAINTS
</code>
</a>
</th>
<td>
Table and column CHECK constraints
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-collation-character-set-applicability-table.html" title="28.3.7 The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table">
<code class="literal">
COLLATION_CHARACTER_SET_APPLICABILITY
</code>
</a>
</th>
<td>
Character set applicable to each collation
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-collations-table.html" title="28.3.6 The INFORMATION_SCHEMA COLLATIONS Table">
<code class="literal">
COLLATIONS
</code>
</a>
</th>
<td>
Collations for each character set
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-column-privileges-table.html" title="28.3.10 The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table">
<code class="literal">
COLUMN_PRIVILEGES
</code>
</a>
</th>
<td>
Privileges defined on columns
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table">
<code class="literal">
COLUMN_STATISTICS
</code>
</a>
</th>
<td>
Histogram statistics for column values
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table">
<code class="literal">
COLUMNS
</code>
</a>
</th>
<td>
Columns in each table
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-columns-extensions-table.html" title="28.3.9 The INFORMATION_SCHEMA COLUMNS_EXTENSIONS Table">
<code class="literal">
COLUMNS_EXTENSIONS
</code>
</a>
</th>
<td>
Column attributes for primary and secondary storage engines
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table">
<code class="literal">
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS
</code>
</a>
</th>
<td>
Current number of consecutive failed connection attempts per account
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-enabled-roles-table.html" title="28.3.12 The INFORMATION_SCHEMA ENABLED_ROLES Table">
<code class="literal">
ENABLED_ROLES
</code>
</a>
</th>
<td>
Roles enabled within current session
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-engines-table.html" title="28.3.13 The INFORMATION_SCHEMA ENGINES Table">
<code class="literal">
ENGINES
</code>
</a>
</th>
<td>
Storage engine properties
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-events-table.html" title="28.3.14 The INFORMATION_SCHEMA EVENTS Table">
<code class="literal">
EVENTS
</code>
</a>
</th>
<td>
Event Manager events
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
FILES
</code>
</a>
</th>
<td>
Files that store tablespace data
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table">
<code class="literal">
INNODB_BUFFER_PAGE
</code>
</a>
</th>
<td>
Pages in InnoDB buffer pool
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table">
<code class="literal">
INNODB_BUFFER_PAGE_LRU
</code>
</a>
</th>
<td>
LRU ordering of pages in InnoDB buffer pool
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table">
<code class="literal">
INNODB_BUFFER_POOL_STATS
</code>
</a>
</th>
<td>
InnoDB buffer pool statistics
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table">
<code class="literal">
INNODB_CACHED_INDEXES
</code>
</a>
</th>
<td>
Number of index pages cached per index in InnoDB buffer pool
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables">
<code class="literal">
INNODB_CMP
</code>
</a>
</th>
<td>
Status for operations related to compressed InnoDB tables
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables">
<code class="literal">
INNODB_CMP_PER_INDEX
</code>
</a>
</th>
<td>
Status for operations related to compressed InnoDB tables and indexes
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables">
<code class="literal">
INNODB_CMP_PER_INDEX_RESET
</code>
</a>
</th>
<td>
Status for operations related to compressed InnoDB tables and indexes
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables">
<code class="literal">
INNODB_CMP_RESET
</code>
</a>
</th>
<td>
Status for operations related to compressed InnoDB tables
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables">
<code class="literal">
INNODB_CMPMEM
</code>
</a>
</th>
<td>
Status for compressed pages within InnoDB buffer pool
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables">
<code class="literal">
INNODB_CMPMEM_RESET
</code>
</a>
</th>
<td>
Status for compressed pages within InnoDB buffer pool
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-columns-table.html" title="28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table">
<code class="literal">
INNODB_COLUMNS
</code>
</a>
</th>
<td>
Columns in each InnoDB table
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table">
<code class="literal">
INNODB_DATAFILES
</code>
</a>
</th>
<td>
Data file path information for InnoDB file-per-table and general tablespaces
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-fields-table.html" title="28.4.11 The INFORMATION_SCHEMA INNODB_FIELDS Table">
<code class="literal">
INNODB_FIELDS
</code>
</a>
</th>
<td>
Key columns of InnoDB indexes
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-foreign-table.html" title="28.4.12 The INFORMATION_SCHEMA INNODB_FOREIGN Table">
<code class="literal">
INNODB_FOREIGN
</code>
</a>
</th>
<td>
InnoDB foreign-key metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-foreign-cols-table.html" title="28.4.13 The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table">
<code class="literal">
INNODB_FOREIGN_COLS
</code>
</a>
</th>
<td>
InnoDB foreign-key column status information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table">
<code class="literal">
INNODB_FT_BEING_DELETED
</code>
</a>
</th>
<td>
Snapshot of INNODB_FT_DELETED table
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table">
<code class="literal">
INNODB_FT_CONFIG
</code>
</a>
</th>
<td>
Metadata for InnoDB table FULLTEXT index and associated processing
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table">
<code class="literal">
INNODB_FT_DEFAULT_STOPWORD
</code>
</a>
</th>
<td>
Default list of stopwords for InnoDB FULLTEXT indexes
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table">
<code class="literal">
INNODB_FT_DELETED
</code>
</a>
</th>
<td>
Rows deleted from InnoDB table FULLTEXT index
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table">
<code class="literal">
INNODB_FT_INDEX_CACHE
</code>
</a>
</th>
<td>
Token information for newly inserted rows in InnoDB FULLTEXT index
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table">
<code class="literal">
INNODB_FT_INDEX_TABLE
</code>
</a>
</th>
<td>
Inverted index information for processing text searches against InnoDB table FULLTEXT index
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table">
<code class="literal">
INNODB_INDEXES
</code>
</a>
</th>
<td>
InnoDB index metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table">
<code class="literal">
INNODB_METRICS
</code>
</a>
</th>
<td>
InnoDB performance information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-session-temp-tablespaces-table.html" title="28.4.22 The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table">
<code class="literal">
INNODB_SESSION_TEMP_TABLESPACES
</code>
</a>
</th>
<td>
Session temporary-tablespace metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-tables-table.html" title="28.4.23 The INFORMATION_SCHEMA INNODB_TABLES Table">
<code class="literal">
INNODB_TABLES
</code>
</a>
</th>
<td>
InnoDB table metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table">
<code class="literal">
INNODB_TABLESPACES
</code>
</a>
</th>
<td>
InnoDB file-per-table, general, and undo tablespace metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table">
<code class="literal">
INNODB_TABLESPACES_BRIEF
</code>
</a>
</th>
<td>
Brief file-per-table, general, undo, and system tablespace metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View">
<code class="literal">
INNODB_TABLESTATS
</code>
</a>
</th>
<td>
InnoDB table low-level status information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-temp-table-info-table.html" title="28.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table">
<code class="literal">
INNODB_TEMP_TABLE_INFO
</code>
</a>
</th>
<td>
Information about active user-created InnoDB temporary tables
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table">
<code class="literal">
INNODB_TRX
</code>
</a>
</th>
<td>
Active InnoDB transaction information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table">
<code class="literal">
INNODB_VIRTUAL
</code>
</a>
</th>
<td>
InnoDB virtual generated column metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-key-column-usage-table.html" title="28.3.16 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table">
<code class="literal">
KEY_COLUMN_USAGE
</code>
</a>
</th>
<td>
Which key columns have constraints
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-keywords-table.html" title="28.3.17 The INFORMATION_SCHEMA KEYWORDS Table">
<code class="literal">
KEYWORDS
</code>
</a>
</th>
<td>
MySQL keywords
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-mysql-firewall-users-table.html" title="28.7.2 The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table">
<code class="literal">
MYSQL_FIREWALL_USERS
</code>
</a>
</th>
<td>
Firewall in-memory data for account profiles
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-mysql-firewall-whitelist-table.html" title="28.7.3 The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table">
<code class="literal">
MYSQL_FIREWALL_WHITELIST
</code>
</a>
</th>
<td>
Firewall in-memory data for account profile allowlists
</td>
<td>
Yes
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-ndb-transid-mysql-connection-map-table.html" title="28.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table">
<code class="literal">
ndb_transid_mysql_connection_map
</code>
</a>
</th>
<td>
NDB transaction information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-optimizer-trace-table.html" title="28.3.19 The INFORMATION_SCHEMA OPTIMIZER_TRACE Table">
<code class="literal">
OPTIMIZER_TRACE
</code>
</a>
</th>
<td>
Information produced by optimizer trace activity
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-parameters-table.html" title="28.3.20 The INFORMATION_SCHEMA PARAMETERS Table">
<code class="literal">
PARAMETERS
</code>
</a>
</th>
<td>
Stored routine parameters and stored function return values
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-partitions-table.html" title="28.3.21 The INFORMATION_SCHEMA PARTITIONS Table">
<code class="literal">
PARTITIONS
</code>
</a>
</th>
<td>
Table partition information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table">
<code class="literal">
PLUGINS
</code>
</a>
</th>
<td>
Plugin information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table">
<code class="literal">
PROCESSLIST
</code>
</a>
</th>
<td>
Information about currently executing threads
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-profiling-table.html" title="28.3.24 The INFORMATION_SCHEMA PROFILING Table">
<code class="literal">
PROFILING
</code>
</a>
</th>
<td>
Statement profiling information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table">
<code class="literal">
REFERENTIAL_CONSTRAINTS
</code>
</a>
</th>
<td>
Foreign key information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-resource-groups-table.html" title="28.3.26 The INFORMATION_SCHEMA RESOURCE_GROUPS Table">
<code class="literal">
RESOURCE_GROUPS
</code>
</a>
</th>
<td>
Resource group information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-role-column-grants-table.html" title="28.3.27 The INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table">
<code class="literal">
ROLE_COLUMN_GRANTS
</code>
</a>
</th>
<td>
Column privileges for roles available to or granted by currently enabled roles
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-role-routine-grants-table.html" title="28.3.28 The INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table">
<code class="literal">
ROLE_ROUTINE_GRANTS
</code>
</a>
</th>
<td>
Routine privileges for roles available to or granted by currently enabled roles
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-role-table-grants-table.html" title="28.3.29 The INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table">
<code class="literal">
ROLE_TABLE_GRANTS
</code>
</a>
</th>
<td>
Table privileges for roles available to or granted by currently enabled roles
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table">
<code class="literal">
ROUTINES
</code>
</a>
</th>
<td>
Stored routine information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-schema-privileges-table.html" title="28.3.33 The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table">
<code class="literal">
SCHEMA_PRIVILEGES
</code>
</a>
</th>
<td>
Privileges defined on schemas
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-schemata-table.html" title="28.3.31 The INFORMATION_SCHEMA SCHEMATA Table">
<code class="literal">
SCHEMATA
</code>
</a>
</th>
<td>
Schema information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-schemata-extensions-table.html" title="28.3.32 The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table">
<code class="literal">
SCHEMATA_EXTENSIONS
</code>
</a>
</th>
<td>
Schema options
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-st-geometry-columns-table.html" title="28.3.35 The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table">
<code class="literal">
ST_GEOMETRY_COLUMNS
</code>
</a>
</th>
<td>
Columns in each table that store spatial data
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-st-spatial-reference-systems-table.html" title="28.3.36 The INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table">
<code class="literal">
ST_SPATIAL_REFERENCE_SYSTEMS
</code>
</a>
</th>
<td>
Available spatial reference systems
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-st-units-of-measure-table.html" title="28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table">
<code class="literal">
ST_UNITS_OF_MEASURE
</code>
</a>
</th>
<td>
Acceptable units for ST_Distance()
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table">
<code class="literal">
STATISTICS
</code>
</a>
</th>
<td>
Table index statistics
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-table-constraints-table.html" title="28.3.41 The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table">
<code class="literal">
TABLE_CONSTRAINTS
</code>
</a>
</th>
<td>
Which tables have constraints
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-table-constraints-extensions-table.html" title="28.3.42 The INFORMATION_SCHEMA TABLE_CONSTRAINTS_EXTENSIONS Table">
<code class="literal">
TABLE_CONSTRAINTS_EXTENSIONS
</code>
</a>
</th>
<td>
Table constraint attributes for primary and secondary storage engines
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-table-privileges-table.html" title="28.3.43 The INFORMATION_SCHEMA TABLE_PRIVILEGES Table">
<code class="literal">
TABLE_PRIVILEGES
</code>
</a>
</th>
<td>
Privileges defined on tables
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table">
<code class="literal">
TABLES
</code>
</a>
</th>
<td>
Table information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table">
<code class="literal">
TABLES_EXTENSIONS
</code>
</a>
</th>
<td>
Table attributes for primary and secondary storage engines
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tablespaces-extensions-table.html" title="28.3.40 The INFORMATION_SCHEMA TABLESPACES_EXTENSIONS Table">
<code class="literal">
TABLESPACES_EXTENSIONS
</code>
</a>
</th>
<td>
Tablespace attributes for primary storage engines
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tp-thread-group-state-table.html" title="28.5.2 The INFORMATION_SCHEMA TP_THREAD_GROUP_STATE Table">
<code class="literal">
TP_THREAD_GROUP_STATE
</code>
</a>
</th>
<td>
Thread pool thread group states
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tp-thread-group-stats-table.html" title="28.5.3 The INFORMATION_SCHEMA TP_THREAD_GROUP_STATS Table">
<code class="literal">
TP_THREAD_GROUP_STATS
</code>
</a>
</th>
<td>
Thread pool thread group statistics
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-tp-thread-state-table.html" title="28.5.4 The INFORMATION_SCHEMA TP_THREAD_STATE Table">
<code class="literal">
TP_THREAD_STATE
</code>
</a>
</th>
<td>
Thread pool thread information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-triggers-table.html" title="28.3.44 The INFORMATION_SCHEMA TRIGGERS Table">
<code class="literal">
TRIGGERS
</code>
</a>
</th>
<td>
Trigger information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table">
<code class="literal">
USER_ATTRIBUTES
</code>
</a>
</th>
<td>
User comments and attributes
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-user-privileges-table.html" title="28.3.46 The INFORMATION_SCHEMA USER_PRIVILEGES Table">
<code class="literal">
USER_PRIVILEGES
</code>
</a>
</th>
<td>
Privileges defined globally per user
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table">
<code class="literal">
VIEW_ROUTINE_USAGE
</code>
</a>
</th>
<td>
Stored functions used in views
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-view-table-usage-table.html" title="28.3.49 The INFORMATION_SCHEMA VIEW_TABLE_USAGE Table">
<code class="literal">
VIEW_TABLE_USAGE
</code>
</a>
</th>
<td>
Tables and views used in views
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="information-schema-views-table.html" title="28.3.47 The INFORMATION_SCHEMA VIEWS Table">
<code class="literal">
VIEWS
</code>
</a>
</th>
<td>
View information
</td>
<td>
</td>
</tr>
</tbody>
</table>
</div>
<div class="table-contents">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;">
<thead>
<tr>
<th style="width: 332.016px;">
Table Name
</th>
<th style="width: 316.828px;">
Description
</th>
<th style="width: 89.1562px;">
Deprecated
</th>
</tr>
</thead>
</table>
</div>
</div>
<br class="table-break"/>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/batch-mode.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="batch-mode">
</a>
5.5 Using mysql in Batch Mode
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045324800112">
</a>
<a class="indexterm" name="idm46045324798656">
</a>
<a class="indexterm" name="idm46045324797584">
</a>
<a class="indexterm" name="idm46045324796096">
</a>
<a class="indexterm" name="idm46045324795024">
</a>
<a class="indexterm" name="idm46045324793536">
</a>
<p>
In the previous sections, you used
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
interactively to enter statements and view the results. You can
also run
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
in batch mode. To do this, put
the statements you want to run in a file, then tell
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
to read its input from the file:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa11174434"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> < <em class="replaceable">batch-file</em></code></pre>
</div>
<p>
If you are running
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
under Windows and have
some special characters in the file that cause problems, you can
do this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa55670718"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> mysql</span> <span class="token property">-e</span> <span class="token atrule">"source <em class="replaceable">batch-file</em>"</span></code></pre>
</div>
<p>
If you need to specify connection parameters on the command line,
the command might look like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa41083408"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <em class="replaceable">host</em> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span> < <em class="replaceable">batch-file</em>
Enter password<span class="token punctuation">:</span> ********</code></pre>
</div>
<p>
When you use
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
this way, you are creating a
script file, then executing the script.
</p>
<p>
If you want the script to continue even if some of the statements
in it produce errors, you should use the
<a class="link" href="mysql-command-options.html#option_mysql_force">
<code class="option">
--force
</code>
</a>
command-line option.
</p>
<p>
Why use a script? Here are a few reasons:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If you run a query repeatedly (say, every day or every week),
making it a script enables you to avoid retyping it each time
you execute it.
</p>
</li>
<li class="listitem">
<p>
You can generate new queries from existing ones that are
similar by copying and editing script files.
</p>
</li>
<li class="listitem">
<p>
Batch mode can also be useful while you're developing a query,
particularly for multiple-line statements or
multiple-statement sequences. If you make a mistake, you don't
have to retype everything. Just edit your script to correct
the error, then tell
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
to execute it
again.
</p>
</li>
<li class="listitem">
<p>
If you have a query that produces a lot of output, you can run
the output through a pager rather than watching it scroll off
the top of your screen:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa36754319"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> < <em class="replaceable">batch-file</em> | more</code></pre>
</div>
</li>
<li class="listitem">
<p>
You can catch the output in a file for further processing:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa12386551"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> < <em class="replaceable">batch-file</em> > mysql<span class="token punctuation">.</span>out</code></pre>
</div>
</li>
<li class="listitem">
<p>
You can distribute your script to other people so that they
can also run the statements.
</p>
</li>
<li class="listitem">
<p>
Some situations do not allow for interactive use, for example,
when you run a query from a
<span class="command">
<strong>
cron
</strong>
</span>
job. In
this case, you must use batch mode.
</p>
</li>
</ul>
</div>
<p>
The default output format is different (more concise) when you run
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
in batch mode than when you use it
interactively. For example, the output of
<code class="literal">
SELECT DISTINCT
species FROM pet
</code>
looks like this when
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
is run interactively:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa667301"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+---------+
| species |
+---------+
| bird |
| cat |
| dog |
| hamster |
| snake |
+---------+</code></pre>
</div>
<p>
In batch mode, the output looks like this instead:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa93617487"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">species
bird
cat
dog
hamster
snake</code></pre>
</div>
<p>
If you want to get the interactive output format in batch mode,
use
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql -t
</strong>
</span>
</a>
. To echo to the output the
statements that are executed, use
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql -v
</strong>
</span>
</a>
.
</p>
<a class="indexterm" name="idm46045324751984">
</a>
<a class="indexterm" name="idm46045324750896">
</a>
<a class="indexterm" name="idm46045324749808">
</a>
<a class="indexterm" name="idm46045324748704">
</a>
<p>
You can also use scripts from the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
prompt
by using the
<code class="literal">
source
</code>
command or
<code class="literal">
\.
</code>
command:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa79207160"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">source</span> <em class="replaceable">filename</em><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> \<span class="token punctuation">.</span> <em class="replaceable">filename</em></code></pre>
</div>
<p>
See
<a class="xref" href="mysql-batch-commands.html" title="6.5.1.5 Executing SQL Statements from a Text File">
Section 6.5.1.5, “Executing SQL Statements from a Text File”
</a>
, for more information.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/charset-binary-set.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="charset-binary-set">
</a>
12.10.8 The Binary Character Set
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045215527344">
</a>
<a class="indexterm" name="idm46045215525888">
</a>
<p>
The
<code class="literal">
binary
</code>
character set is the character set
for binary strings, which are sequences of bytes. The
<code class="literal">
binary
</code>
character set has one collation, also
named
<code class="literal">
binary
</code>
. Comparison and sorting are
based on numeric byte values, rather than on numeric character
code values (which for multibyte characters differ from numeric
byte values). For information about the differences between the
<code class="literal">
binary
</code>
collation of the
<code class="literal">
binary
</code>
character set and the
<code class="literal">
_bin
</code>
collations of nonbinary character sets,
see
<a class="xref" href="charset-binary-collations.html" title="12.8.5 The binary Collation Compared to _bin Collations">
Section 12.8.5, “The binary Collation Compared to _bin Collations”
</a>
.
</p>
<p>
For the
<code class="literal">
binary
</code>
character set, the concepts of
lettercase and accent equivalence do not apply:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
For single-byte characters stored as binary strings,
character and byte boundaries are the same, so lettercase
and accent differences are significant in comparisons. That
is, the
<code class="literal">
binary
</code>
collation is
case-sensitive and accent-sensitive.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4592274"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token keyword">NAMES</span> <span class="token string">'binary'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">CHARSET</span><span class="token punctuation">(</span><span class="token string">'abc'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">COLLATION</span><span class="token punctuation">(</span><span class="token string">'abc'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CHARSET('abc') <span class="token punctuation">|</span> COLLATION('abc') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> binary <span class="token punctuation">|</span> binary <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token string">'abc'</span> <span class="token operator">=</span> <span class="token string">'ABC'</span><span class="token punctuation">,</span> <span class="token string">'a'</span> <span class="token operator">=</span> <span class="token string">'ä'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 'abc' = 'ABC' <span class="token punctuation">|</span> 'a' = 'ä' <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 0 <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
For multibyte characters stored as binary strings, character
and byte boundaries differ. Character boundaries are lost,
so comparisons that depend on them are not meaningful.
</p>
</li>
</ul>
</div>
<p>
To perform lettercase conversion of a binary string, first
convert it to a nonbinary string using a character set
appropriate for the data stored in the string:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35600316"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@str</span> <span class="token operator">=</span> <span class="token datatype">BINARY</span> <span class="token string">'New York'</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">LOWER</span><span class="token punctuation">(</span><span class="token variable">@str</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">LOWER</span><span class="token punctuation">(</span><span class="token function">CONVERT</span><span class="token punctuation">(</span><span class="token variable">@str</span> <span class="token keyword">USING</span> utf8mb4<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LOWER(@str) <span class="token punctuation">|</span> LOWER(CONVERT(@str USING utf8mb4)) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> New York <span class="token punctuation">|</span> new york <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
To convert a string expression to a binary string, these
constructs are equivalent:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5636077"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token datatype">BINARY</span> <em class="replaceable">expr</em>
<span class="token function">CAST</span><span class="token punctuation">(</span><em class="replaceable">expr</em> <span class="token keyword">AS</span> <span class="token datatype">BINARY</span><span class="token punctuation">)</span>
<span class="token function">CONVERT</span><span class="token punctuation">(</span><em class="replaceable">expr</em> <span class="token keyword">USING</span> <span class="token datatype">BINARY</span><span class="token punctuation">)</span></code></pre>
</div>
<a class="indexterm" name="idm46045215504224">
</a>
<p>
If a value is a character string literal, the
<code class="literal">
_binary
</code>
introducer may be used to designate
it as a binary string. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa6300024"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">_binary <span class="token string">'a'</span></code></pre>
</div>
<p>
The
<code class="literal">
_binary
</code>
introducer is permitted for
hexadecimal literals and bit-value literals as well, but
unnecessary; such literals are binary strings by default.
</p>
<p>
For more information about introducers, see
<a class="xref" href="charset-introducer.html" title="12.3.8 Character Set Introducers">
Section 12.3.8, “Character Set Introducers”
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
Within the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client, binary strings
display using hexadecimal notation, depending on the value of
the
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
. For more
information about that option, see
<a class="xref" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
Section 6.5.1, “mysql — The MySQL Command-Line Client”
</a>
.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/with.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="with">
</a>
15.2.20 WITH (Common Table Expressions)
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045179219200">
</a>
<p>
A common table expression (CTE) is a named temporary result set
that exists within the scope of a single statement and that can be
referred to later within that statement, possibly multiple times.
The following discussion describes how to write statements that
use CTEs.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions" title="Common Table Expressions">
Common Table Expressions
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursive" title="Recursive Common Table Expressions">
Recursive Common Table Expressions
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursion-limits" title="Limiting Common Table Expression Recursion">
Limiting Common Table Expression Recursion
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursive-examples" title="Recursive Common Table Expression Examples">
Recursive Common Table Expression Examples
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-similar-constructs" title="Common Table Expressions Compared to Similar Constructs">
Common Table Expressions Compared to Similar Constructs
</a>
</p>
</li>
</ul>
</div>
<p>
For information about CTE optimization, see
<a class="xref" href="derived-table-optimization.html" title="10.2.2.4 Optimizing Derived Tables, View References, and Common Table Expressions with Merging or Materialization">
Section 10.2.2.4, “Optimizing Derived Tables, View References, and Common Table Expressions
with Merging or Materialization”
</a>
.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="common-table-expressions">
</a>
Common Table Expressions
</h4>
</div>
</div>
</div>
<p>
To specify common table expressions, use a
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause that has one or more
comma-separated subclauses. Each subclause provides a subquery
that produces a result set, and associates a name with the
subquery. The following example defines CTEs named
<code class="literal">
cte1
</code>
and
<code class="literal">
cte2
</code>
in the
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause, and refers to them
in the top-level
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
that
follows the
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa70033151"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span>
cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> a<span class="token punctuation">,</span> b <span class="token keyword">FROM</span> table1<span class="token punctuation">)</span><span class="token punctuation">,</span>
cte2 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> c<span class="token punctuation">,</span> d <span class="token keyword">FROM</span> table2<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> b<span class="token punctuation">,</span> d <span class="token keyword">FROM</span> cte1 <span class="token keyword">JOIN</span> cte2
<span class="token keyword">WHERE</span> cte1<span class="token punctuation">.</span>a <span class="token operator">=</span> cte2<span class="token punctuation">.</span>c<span class="token punctuation">;</span></code></pre>
</div>
<p>
In the statement containing the
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause, each CTE name can be
referenced to access the corresponding CTE result set.
</p>
<p>
A CTE name can be referenced in other CTEs, enabling CTEs to be
defined based on other CTEs.
</p>
<p>
A CTE can refer to itself to define a recursive CTE. Common
applications of recursive CTEs include series generation and
traversal of hierarchical or tree-structured data.
</p>
<p>
Common table expressions are an optional part of the syntax for
DML statements. They are defined using a
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa79876892"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><em class="replaceable">with_clause</em>:
<span class="token keyword">WITH</span> <span class="token punctuation">[</span><span class="token keyword">RECURSIVE</span><span class="token punctuation">]</span>
<em class="replaceable">cte_name</em> <span class="token punctuation">[</span><span class="token punctuation">(</span><em class="replaceable">col_name</em> <span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">col_name</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">]</span> <span class="token keyword">AS</span> <span class="token punctuation">(</span><em class="replaceable">subquery</em><span class="token punctuation">)</span>
<span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">cte_name</em> <span class="token punctuation">[</span><span class="token punctuation">(</span><em class="replaceable">col_name</em> <span class="token punctuation">[</span><span class="token punctuation">,</span> <em class="replaceable">col_name</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">]</span> <span class="token keyword">AS</span> <span class="token punctuation">(</span><em class="replaceable">subquery</em><span class="token punctuation">)</span><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
<em class="replaceable">
<code>
cte_name
</code>
</em>
names a single common table
expression and can be used as a table reference in the statement
containing the
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause.
</p>
<p>
The
<em class="replaceable">
<code>
subquery
</code>
</em>
part of
<code class="literal">
AS
(
<em class="replaceable">
<code>
subquery
</code>
</em>
)
</code>
is called the
<span class="quote">
“
<span class="quote">
subquery of the CTE
</span>
”
</span>
and is what produces the CTE
result set. The parentheses following
<code class="literal">
AS
</code>
are
required.
</p>
<p>
A common table expression is recursive if its subquery refers to
its own name. The
<code class="literal">
RECURSIVE
</code>
keyword must be
included if any CTE in the
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause is recursive. For more information, see
<a class="xref" href="with.html#common-table-expressions-recursive" title="Recursive Common Table Expressions">
Recursive Common Table Expressions
</a>
.
</p>
<p>
Determination of column names for a given CTE occurs as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If a parenthesized list of names follows the CTE name, those
names are the column names:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa82263299"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> col2 <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
The number of names in the list must be the same as the
number of columns in the result set.
</p>
</li>
<li class="listitem">
<p>
Otherwise, the column names come from the select list of the
first
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
within the
<code class="literal">
AS (
<em class="replaceable">
<code>
subquery
</code>
</em>
)
</code>
part:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa13662318"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span> <span class="token keyword">AS</span> col1<span class="token punctuation">,</span> <span class="token number">2</span> <span class="token keyword">AS</span> col2
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> col1<span class="token punctuation">,</span> col2 <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
A
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause is permitted in
these contexts:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
At the beginning of
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
, and
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statements.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa8925294"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">UPDATE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">DELETE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
At the beginning of subqueries (including derived table
subqueries):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa61887833"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WHERE</span> id <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> <span class="token punctuation">(</span><span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> dt <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Immediately preceding
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
for statements that include a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67203631"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">REPLACE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">CREATE</span> <span class="token keyword">VIEW</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">DECLARE</span> <span class="token keyword">CURSOR</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">EXPLAIN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">WITH</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
Only one
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause is permitted
at the same level.
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
followed
by
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
at the same level is not
permitted, so this is illegal:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa62557073"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">WITH</span> cte2 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
To make the statement legal, use a single
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause that separates the
subclauses by a comma:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa31331961"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cte2 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
However, a statement can contain multiple
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clauses if they occur at
different levels:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa13751374"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token number">1</span><span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> <span class="token punctuation">(</span><span class="token keyword">WITH</span> cte2 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte2 <span class="token keyword">JOIN</span> cte1<span class="token punctuation">)</span> <span class="token keyword">AS</span> dt<span class="token punctuation">;</span></code></pre>
</div>
<p>
A
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause can define one or
more common table expressions, but each CTE name must be unique
to the clause. This is illegal:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54445303"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
To make the statement legal, define the CTEs with unique names:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa63541151"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte1 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span><span class="token punctuation">,</span> cte2 <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
A CTE can refer to itself or to other CTEs:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
A self-referencing CTE is recursive.
</p>
</li>
<li class="listitem">
<p>
A CTE can refer to CTEs defined earlier in the same
<a class="link" href="with.html" title="15.2.20 WITH (Common Table Expressions)">
<code class="literal">
WITH
</code>
</a>
clause, but not those
defined later.
</p>
<p>
This constraint rules out mutually-recursive CTEs, where
<code class="literal">
cte1
</code>
references
<code class="literal">
cte2
</code>
and
<code class="literal">
cte2
</code>
references
<code class="literal">
cte1
</code>
. One of those references must be to
a CTE defined later, which is not permitted.
</p>
</li>
<li class="listitem">
<p>
A CTE in a given query block can refer to CTEs defined in
query blocks at a more outer level, but not CTEs defined in
query blocks at a more inner level.
</p>
</li>
</ul>
</div>
<p>
For resolving references to objects with the same names, derived
tables hide CTEs; and CTEs hide base tables,
<code class="literal">
TEMPORARY
</code>
tables, and views. Name resolution
occurs by searching for objects in the same query block, then
proceeding to outer blocks in turn while no object with the name
is found.
</p>
<p>
For additional syntax considerations specific to recursive CTEs,
see
<a class="xref" href="with.html#common-table-expressions-recursive" title="Recursive Common Table Expressions">
Recursive Common Table Expressions
</a>
.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="common-table-expressions-recursive">
</a>
Recursive Common Table Expressions
</h4>
</div>
</div>
</div>
<p>
A recursive common table expression is one having a subquery
that refers to its own name. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40900484"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">5</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
When executed, the statement produces this result, a single
column containing a simple linear sequence:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa11621629"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+
| n |
+------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+------+</code></pre>
</div>
<p>
A recursive CTE has this structure:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<code class="literal">
WITH
</code>
clause must begin with
<code class="literal">
WITH RECURSIVE
</code>
if any CTE in the
<code class="literal">
WITH
</code>
clause refers to itself. (If no CTE
refers to itself,
<code class="literal">
RECURSIVE
</code>
is permitted
but not required.)
</p>
<p>
If you forget
<code class="literal">
RECURSIVE
</code>
for a recursive
CTE, this error is a likely result:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa92576476"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR 1146 (42S02): Table '<em class="replaceable">cte_name</em>' doesn't exist</code></pre>
</div>
</li>
<li class="listitem">
<p>
The recursive CTE subquery has two parts, separated by
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION ALL
</code>
</a>
or
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION
[DISTINCT]
</code>
</a>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa2865183"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token comment" spellcheck="true">-- return initial row set</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token comment" spellcheck="true">-- return additional row sets</span></code></pre>
</div>
<p>
The first
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
produces the
initial row or rows for the CTE and does not refer to the
CTE name. The second
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
produces additional rows and recurses by referring to the
CTE name in its
<code class="literal">
FROM
</code>
clause. Recursion
ends when this part produces no new rows. Thus, a recursive
CTE consists of a nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part followed by a
recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part.
</p>
<p>
Each
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part can itself
be a union of multiple
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements.
</p>
</li>
<li class="listitem">
<p>
The types of the CTE result columns are inferred from the
column types of the nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part only, and the
columns are all nullable. For type determination, the
recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part is
ignored.
</p>
</li>
<li class="listitem">
<p>
If the nonrecursive and recursive parts are separated by
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION
DISTINCT
</code>
</a>
, duplicate rows are eliminated. This is
useful for queries that perform transitive closures, to
avoid infinite loops.
</p>
</li>
<li class="listitem">
<p>
Each iteration of the recursive part operates only on the
rows produced by the previous iteration. If the recursive
part has multiple query blocks, iterations of each query
block are scheduled in unspecified order, and each query
block operates on rows that have been produced either by its
previous iteration or by other query blocks since that
previous iteration's end.
</p>
</li>
</ul>
</div>
<p>
The recursive CTE subquery shown earlier has this nonrecursive
part that retrieves a single row to produce the initial row set:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa23288940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token number">1</span></code></pre>
</div>
<p>
The CTE subquery also has this recursive part:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa31955617"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">5</span></code></pre>
</div>
<p>
At each iteration, that
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
produces a row with a new value one greater than the value of
<code class="literal">
n
</code>
from the previous row set. The first
iteration operates on the initial row set (
<code class="literal">
1
</code>
)
and produces
<code class="literal">
1+1=2
</code>
; the second iteration
operates on the first iteration's row set (
<code class="literal">
2
</code>
)
and produces
<code class="literal">
2+1=3
</code>
; and so forth. This
continues until recursion ends, which occurs when
<code class="literal">
n
</code>
is no longer less than 5.
</p>
<p>
If the recursive part of a CTE produces wider values for a
column than the nonrecursive part, it may be necessary to widen
the column in the nonrecursive part to avoid data truncation.
Consider this statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25813355"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span> <span class="token keyword">AS</span> n<span class="token punctuation">,</span> <span class="token string">'abc'</span> <span class="token keyword">AS</span> str
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>str<span class="token punctuation">,</span> str<span class="token punctuation">)</span> <span class="token keyword">FROM</span> cte <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">3</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
In nonstrict SQL mode, the statement produces this output:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa55773981"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+------+
| n | str |
+------+------+
| 1 | abc |
| 2 | abc |
| 3 | abc |
+------+------+</code></pre>
</div>
<p>
The
<code class="literal">
str
</code>
column values are all
<code class="literal">
'abc'
</code>
because the nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
determines the column
widths. Consequently, the wider
<code class="literal">
str
</code>
values
produced by the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
are truncated.
</p>
<p>
In strict SQL mode, the statement produces an error:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa8066915"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR 1406 (22001): Data too long for column 'str' at row 1</code></pre>
</div>
<p>
To address this issue, so that the statement does not produce
truncation or errors, use
<a class="link" href="cast-functions.html#function_cast">
<code class="literal">
CAST()
</code>
</a>
in the nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
to
make the
<code class="literal">
str
</code>
column wider:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46098292"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span> <span class="token keyword">AS</span> n<span class="token punctuation">,</span> <span class="token function">CAST</span><span class="token punctuation">(</span><span class="token string">'abc'</span> <span class="token keyword">AS</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> str
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>str<span class="token punctuation">,</span> str<span class="token punctuation">)</span> <span class="token keyword">FROM</span> cte <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">3</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
Now the statement produces this result, without truncation:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa50040594"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+--------------+
| n | str |
+------+--------------+
| 1 | abc |
| 2 | abcabc |
| 3 | abcabcabcabc |
+------+--------------+</code></pre>
</div>
<p>
Columns are accessed by name, not position, which means that
columns in the recursive part can access columns in the
nonrecursive part that have a different position, as this CTE
illustrates:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72888319"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span> <span class="token keyword">AS</span> n<span class="token punctuation">,</span> <span class="token number">1</span> <span class="token keyword">AS</span> p<span class="token punctuation">,</span> <span class="token operator">-</span><span class="token number">1</span> <span class="token keyword">AS</span> q
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> q <span class="token operator">*</span> <span class="token number">2</span><span class="token punctuation">,</span> p <span class="token operator">*</span> <span class="token number">2</span> <span class="token keyword">FROM</span> cte <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">5</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
Because
<code class="literal">
p
</code>
in one row is derived from
<code class="literal">
q
</code>
in the previous row, and vice versa, the
positive and negative values swap positions in each successive
row of the output:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa73772831"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+------+------+
| n | p | q |
+------+------+------+
| 1 | 1 | -1 |
| 2 | -2 | 2 |
| 3 | 4 | -4 |
| 4 | -8 | 8 |
| 5 | 16 | -16 |
+------+------+------+</code></pre>
</div>
<p>
Some syntax constraints apply within recursive CTE subqueries:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part
must not contain these constructs:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Aggregate functions such as
<code class="literal">
SUM()
</code>
</p>
</li>
<li class="listitem">
<p>
Window functions
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
GROUP BY
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ORDER BY
</code>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
DISTINCT
</code>
</p>
</li>
</ul>
</div>
<p>
The recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part of
a recursive CTE can also use a
<code class="literal">
LIMIT
</code>
clause, along with an optional
<code class="literal">
OFFSET
</code>
clause. The effect on the result set is the same as when
using
<code class="literal">
LIMIT
</code>
in the outermost
<code class="literal">
SELECT
</code>
, but is also more efficient, since
using it with the recursive
<code class="literal">
SELECT
</code>
stops
the generation of rows as soon as the requested number of
them has been produced.
</p>
<p>
The prohibition on
<code class="literal">
DISTINCT
</code>
applies only
to
<a class="link" href="union.html" title="15.2.18 UNION Clause">
<code class="literal">
UNION
</code>
</a>
members;
<code class="literal">
UNION DISTINCT
</code>
is permitted.
</p>
</li>
<li class="listitem">
<p>
The recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part
must reference the CTE only once and only in its
<code class="literal">
FROM
</code>
clause, not in any subquery. It can
reference tables other than the CTE and join them with the
CTE. If used in a join like this, the CTE must not be on the
right side of a
<code class="literal">
LEFT JOIN
</code>
.
</p>
</li>
</ul>
</div>
<p>
These constraints come from the SQL standard, other than the
MySQL-specific exclusions mentioned previously.
</p>
<p>
For recursive CTEs,
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
output rows for recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
parts display
<code class="literal">
Recursive
</code>
in the
<code class="literal">
Extra
</code>
column.
</p>
<p>
Cost estimates displayed by
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
represent cost per
iteration, which might differ considerably from total cost. The
optimizer cannot predict the number of iterations because it
cannot predict at what point the
<code class="literal">
WHERE
</code>
clause
becomes false.
</p>
<p>
CTE actual cost may also be affected by result set size. A CTE
that produces many rows may require an internal temporary table
large enough to be converted from in-memory to on-disk format
and may suffer a performance penalty. If so, increasing the
permitted in-memory temporary table size may improve
performance; see
<a class="xref" href="internal-temporary-tables.html" title="10.4.4 Internal Temporary Table Use in MySQL">
Section 10.4.4, “Internal Temporary Table Use in MySQL”
</a>
.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="common-table-expressions-recursion-limits">
</a>
Limiting Common Table Expression Recursion
</h4>
</div>
</div>
</div>
<p>
It is important for recursive CTEs that the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
part include a condition
to terminate recursion. As a development technique to guard
against a runaway recursive CTE, you can force termination by
placing a limit on execution time:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth">
<code class="literal">
cte_max_recursion_depth
</code>
</a>
system variable enforces a limit on the number of recursion
levels for CTEs. The server terminates execution of any CTE
that recurses more levels than the value of this variable.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="server-system-variables.html#sysvar_max_execution_time">
<code class="literal">
max_execution_time
</code>
</a>
system variable enforces an execution timeout for
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements executed
within the current session.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="optimizer-hints.html#optimizer-hints-execution-time" title="Statement Execution Time Optimizer Hints">
<code class="literal">
MAX_EXECUTION_TIME
</code>
</a>
optimizer hint enforces a per-query execution timeout for
the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement in which
it appears.
</p>
</li>
</ul>
</div>
<p>
Suppose that a recursive CTE is mistakenly written with no
recursion execution termination condition:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69040439"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
By default,
<a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth">
<code class="literal">
cte_max_recursion_depth
</code>
</a>
has a
value of 1000, causing the CTE to terminate when it recurses
past 1000 levels. Applications can change the session value to
adjust for their requirements:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3736616"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">SESSION</span> cte_max_recursion_depth <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">-- permit only shallow recursion</span>
<span class="token keyword">SET</span> <span class="token keyword">SESSION</span> cte_max_recursion_depth <span class="token operator">=</span> <span class="token number">1000000</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">-- permit deeper recursion</span></code></pre>
</div>
<p>
You can also set the global
<a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth">
<code class="literal">
cte_max_recursion_depth
</code>
</a>
value
to affect all sessions that begin subsequently.
</p>
<p>
For queries that execute and thus recurse slowly or in contexts
for which there is reason to set the
<a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth">
<code class="literal">
cte_max_recursion_depth
</code>
</a>
value
very high, another way to guard against deep recursion is to set
a per-session timeout. To do so, execute a statement like this
prior to executing the CTE statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa63375844"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> max_execution_time <span class="token operator">=</span> <span class="token number">1000</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">-- impose one second timeout</span></code></pre>
</div>
<p>
Alternatively, include an optimizer hint within the CTE
statement itself:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5480715"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token comment" spellcheck="true">/*+ SET_VAR(cte_max_recursion_depth = 1M) */</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span>
<span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token comment" spellcheck="true">/*+ MAX_EXECUTION_TIME(1000) */</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
You can also use
<code class="literal">
LIMIT
</code>
within the recursive
query to impose a maximum number of rows to be returned to the
outermost
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
, for example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa71108748"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte <span class="token keyword">LIMIT</span> <span class="token number">10000</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<p>
You can do this in addition to or instead of setting a time
limit. Thus, the following CTE terminates after returning ten
thousand rows or running for one second (1000 milliseconds),
whichever occurs first:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5464861"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> cte <span class="token punctuation">(</span>n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span> <span class="token keyword">FROM</span> cte <span class="token keyword">LIMIT</span> <span class="token number">10000</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token comment" spellcheck="true">/*+ MAX_EXECUTION_TIME(1000) */</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span></code></pre>
</div>
<a class="indexterm" name="idm46045179012944">
</a>
<a class="indexterm" name="idm46045179011456">
</a>
<p>
If a recursive query without an execution time limit enters an
infinite loop, you can terminate it from another session using
<a class="link" href="kill.html" title="15.7.8.4 KILL Statement">
<code class="literal">
KILL QUERY
</code>
</a>
.
Within the session itself, the client program used to run the
query might provide a way to kill the query. For example, in
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
, typing
<span class="keycap">
<strong>
Control+C
</strong>
</span>
interrupts the current statement.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="common-table-expressions-recursive-examples">
</a>
Recursive Common Table Expression Examples
</h4>
</div>
</div>
</div>
<p>
As mentioned previously, recursive common table expressions
(CTEs) are frequently used for series generation and traversing
hierarchical or tree-structured data. This section shows some
simple examples of these techniques.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursive-fibonacci-series" title="Fibonacci Series Generation">
Fibonacci Series Generation
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursive-date-series" title="Date Series Generation">
Date Series Generation
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="with.html#common-table-expressions-recursive-hierarchy-traversal" title="Hierarchical Data Traversal">
Hierarchical Data Traversal
</a>
</p>
</li>
</ul>
</div>
<h5>
<a name="common-table-expressions-recursive-fibonacci-series">
</a>
Fibonacci Series Generation
</h5>
<p>
A Fibonacci series begins with the two numbers 0 and 1 (or 1 and
1) and each number after that is the sum of the previous two
numbers. A recursive common table expression can generate a
Fibonacci series if each row produced by the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
has access to the two
previous numbers from the series. The following CTE generates a
10-number series using 0 and 1 as the first two numbers:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72856105"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> fibonacci <span class="token punctuation">(</span>n<span class="token punctuation">,</span> fib_n<span class="token punctuation">,</span> next_fib_n<span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> n <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> next_fib_n<span class="token punctuation">,</span> fib_n <span class="token operator">+</span> next_fib_n
<span class="token keyword">FROM</span> fibonacci <span class="token keyword">WHERE</span> n <span class="token operator"><</span> <span class="token number">10</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> fibonacci<span class="token punctuation">;</span></code></pre>
</div>
<p>
The CTE produces this result:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa17982288"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+-------+------------+
| n | fib_n | next_fib_n |
+------+-------+------------+
| 1 | 0 | 1 |
| 2 | 1 | 1 |
| 3 | 1 | 2 |
| 4 | 2 | 3 |
| 5 | 3 | 5 |
| 6 | 5 | 8 |
| 7 | 8 | 13 |
| 8 | 13 | 21 |
| 9 | 21 | 34 |
| 10 | 34 | 55 |
+------+-------+------------+</code></pre>
</div>
<p>
How the CTE works:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
n
</code>
is a display column to indicate that
the row contains the
<code class="literal">
n
</code>
-th Fibonacci
number. For example, the 8th Fibonacci number is 13.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
fib_n
</code>
column displays Fibonacci
number
<code class="literal">
n
</code>
.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
next_fib_n
</code>
column displays the next
Fibonacci number after number
<code class="literal">
n
</code>
. This
column provides the next series value to the next row, so
that row can produce the sum of the two previous series
values in its
<code class="literal">
fib_n
</code>
column.
</p>
</li>
<li class="listitem">
<p>
Recursion ends when
<code class="literal">
n
</code>
reaches 10. This is
an arbitrary choice, to limit the output to a small set of
rows.
</p>
</li>
</ul>
</div>
<p>
The preceding output shows the entire CTE result. To select just
part of it, add an appropriate
<code class="literal">
WHERE
</code>
clause
to the top-level
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
. For
example, to select the 8th Fibonacci number, do this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72431031"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> fibonacci <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">SELECT</span> fib_n <span class="token keyword">FROM</span> fibonacci <span class="token keyword">WHERE</span> n <span class="token operator">=</span> <span class="token number">8</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> fib_n <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 13 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<h5>
<a name="common-table-expressions-recursive-date-series">
</a>
Date Series Generation
</h5>
<p>
A common table expression can generate a series of successive
dates, which is useful for generating summaries that include a
row for all dates in the series, including dates not represented
in the summarized data.
</p>
<p>
Suppose that a table of sales numbers contains these rows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37399719"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> sales <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token datatype">date</span><span class="token punctuation">,</span> price<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> date <span class="token punctuation">|</span> price <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>03 <span class="token punctuation">|</span> 100.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>03 <span class="token punctuation">|</span> 200.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>06 <span class="token punctuation">|</span> 50.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>08 <span class="token punctuation">|</span> 10.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>08 <span class="token punctuation">|</span> 20.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>08 <span class="token punctuation">|</span> 150.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>10 <span class="token punctuation">|</span> 5.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
This query summarizes the sales per day:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa44738455"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">date</span><span class="token punctuation">,</span> <span class="token function">SUM</span><span class="token punctuation">(</span>price<span class="token punctuation">)</span> <span class="token keyword">AS</span> sum_price
<span class="token keyword">FROM</span> sales
<span class="token keyword">GROUP</span> <span class="token keyword">BY</span> <span class="token datatype">date</span>
<span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token datatype">date</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> date <span class="token punctuation">|</span> sum_price <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>03 <span class="token punctuation">|</span> 300.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>06 <span class="token punctuation">|</span> 50.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>08 <span class="token punctuation">|</span> 180.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2017<span class="token punctuation">-</span>01<span class="token punctuation">-</span>10 <span class="token punctuation">|</span> 5.00 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
However, that result contains
<span class="quote">
“
<span class="quote">
holes
</span>
”
</span>
for dates not
represented in the range of dates spanned by the table. A result
that represents all dates in the range can be produced using a
recursive CTE to generate that set of dates, joined with a
<code class="literal">
LEFT JOIN
</code>
to the sales data.
</p>
<p>
Here is the CTE to generate the date range series:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa81659329"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> dates <span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">MIN</span><span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> sales
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> <span class="token datatype">date</span> <span class="token operator">+</span> <span class="token keyword">INTERVAL</span> <span class="token number">1</span> <span class="token keyword">DAY</span> <span class="token keyword">FROM</span> dates
<span class="token keyword">WHERE</span> <span class="token datatype">date</span> <span class="token operator">+</span> <span class="token keyword">INTERVAL</span> <span class="token number">1</span> <span class="token keyword">DAY</span> <span class="token operator"><=</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">MAX</span><span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> sales<span class="token punctuation">)</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> dates<span class="token punctuation">;</span></code></pre>
</div>
<p>
The CTE produces this result:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa18744047"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------------+
| date |
+------------+
| 2017-01-03 |
| 2017-01-04 |
| 2017-01-05 |
| 2017-01-06 |
| 2017-01-07 |
| 2017-01-08 |
| 2017-01-09 |
| 2017-01-10 |
+------------+</code></pre>
</div>
<p>
How the CTE works:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
produces the lowest date in the date range spanned by the
<code class="literal">
sales
</code>
table.
</p>
</li>
<li class="listitem">
<p>
Each row produced by the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
adds one day to the
date produced by the previous row.
</p>
</li>
<li class="listitem">
<p>
Recursion ends after the dates reach the highest date in the
date range spanned by the
<code class="literal">
sales
</code>
table.
</p>
</li>
</ul>
</div>
<p>
Joining the CTE with a
<code class="literal">
LEFT JOIN
</code>
against the
<code class="literal">
sales
</code>
table produces the sales summary with a
row for each date in the range:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21718369"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> dates <span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> <span class="token function">MIN</span><span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> sales
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> <span class="token datatype">date</span> <span class="token operator">+</span> <span class="token keyword">INTERVAL</span> <span class="token number">1</span> <span class="token keyword">DAY</span> <span class="token keyword">FROM</span> dates
<span class="token keyword">WHERE</span> <span class="token datatype">date</span> <span class="token operator">+</span> <span class="token keyword">INTERVAL</span> <span class="token number">1</span> <span class="token keyword">DAY</span> <span class="token operator"><=</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">MAX</span><span class="token punctuation">(</span><span class="token datatype">date</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> sales<span class="token punctuation">)</span>
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> dates<span class="token punctuation">.</span><span class="token datatype">date</span><span class="token punctuation">,</span> <span class="token function">COALESCE</span><span class="token punctuation">(</span><span class="token function">SUM</span><span class="token punctuation">(</span>price<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> sum_price
<span class="token keyword">FROM</span> dates <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> sales <span class="token keyword">ON</span> dates<span class="token punctuation">.</span><span class="token datatype">date</span> <span class="token operator">=</span> sales<span class="token punctuation">.</span><span class="token datatype">date</span>
<span class="token keyword">GROUP</span> <span class="token keyword">BY</span> dates<span class="token punctuation">.</span><span class="token datatype">date</span>
<span class="token keyword">ORDER</span> <span class="token keyword">BY</span> dates<span class="token punctuation">.</span><span class="token datatype">date</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
The output looks like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa40731376"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------------+-----------+
| date | sum_price |
+------------+-----------+
| 2017-01-03 | 300.00 |
| 2017-01-04 | 0.00 |
| 2017-01-05 | 0.00 |
| 2017-01-06 | 50.00 |
| 2017-01-07 | 0.00 |
| 2017-01-08 | 180.00 |
| 2017-01-09 | 0.00 |
| 2017-01-10 | 5.00 |
+------------+-----------+</code></pre>
</div>
<p>
Some points to note:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Are the queries inefficient, particularly the one with the
<a class="link" href="aggregate-functions.html#function_max">
<code class="literal">
MAX()
</code>
</a>
subquery executed for
each row in the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
?
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
shows that the
subquery containing
<a class="link" href="aggregate-functions.html#function_max">
<code class="literal">
MAX()
</code>
</a>
is
evaluated only once and the result is cached.
</p>
</li>
<li class="listitem">
<p>
The use of
<a class="link" href="comparison-operators.html#function_coalesce">
<code class="literal">
COALESCE()
</code>
</a>
avoids
displaying
<code class="literal">
NULL
</code>
in the
<code class="literal">
sum_price
</code>
column on days for which no
sales data occur in the
<code class="literal">
sales
</code>
table.
</p>
</li>
</ul>
</div>
<h5>
<a name="common-table-expressions-recursive-hierarchy-traversal">
</a>
Hierarchical Data Traversal
</h5>
<p>
Recursive common table expressions are useful for traversing
data that forms a hierarchy. Consider these statements that
create a small data set that shows, for each employee in a
company, the employee name and ID number, and the ID of the
employee's manager. The top-level employee (the CEO), has a
manager ID of
<code class="literal">
NULL
</code>
(no manager).
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa51828502"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> employees <span class="token punctuation">(</span>
id <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">100</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
manager_id <span class="token datatype">INT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token keyword">INDEX</span> <span class="token punctuation">(</span>manager_id<span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token keyword">FOREIGN</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>manager_id<span class="token punctuation">)</span> <span class="token keyword">REFERENCES</span> employees <span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">VALUES</span>
<span class="token punctuation">(</span><span class="token number">333</span><span class="token punctuation">,</span> <span class="token string">"Yasmina"</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token comment" spellcheck="true"># Yasmina is the CEO (manager_id is NULL)</span>
<span class="token punctuation">(</span><span class="token number">198</span><span class="token punctuation">,</span> <span class="token string">"John"</span><span class="token punctuation">,</span> <span class="token number">333</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token comment" spellcheck="true"># John has ID 198 and reports to 333 (Yasmina)</span>
<span class="token punctuation">(</span><span class="token number">692</span><span class="token punctuation">,</span> <span class="token string">"Tarek"</span><span class="token punctuation">,</span> <span class="token number">333</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token number">29</span><span class="token punctuation">,</span> <span class="token string">"Pedro"</span><span class="token punctuation">,</span> <span class="token number">198</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token number">4610</span><span class="token punctuation">,</span> <span class="token string">"Sarah"</span><span class="token punctuation">,</span> <span class="token number">29</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token number">72</span><span class="token punctuation">,</span> <span class="token string">"Pierre"</span><span class="token punctuation">,</span> <span class="token number">29</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token number">123</span><span class="token punctuation">,</span> <span class="token string">"Adil"</span><span class="token punctuation">,</span> <span class="token number">692</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
The resulting data set looks like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67534927"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> id<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> name <span class="token punctuation">|</span> manager_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 29 <span class="token punctuation">|</span> Pedro <span class="token punctuation">|</span> 198 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 72 <span class="token punctuation">|</span> Pierre <span class="token punctuation">|</span> 29 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 123 <span class="token punctuation">|</span> Adil <span class="token punctuation">|</span> 692 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 198 <span class="token punctuation">|</span> John <span class="token punctuation">|</span> 333 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 333 <span class="token punctuation">|</span> Yasmina <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 692 <span class="token punctuation">|</span> Tarek <span class="token punctuation">|</span> 333 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4610 <span class="token punctuation">|</span> Sarah <span class="token punctuation">|</span> 29 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
To produce the organizational chart with the management chain
for each employee (that is, the path from CEO to employee), use
a recursive CTE:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa50874707"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> employee_paths <span class="token punctuation">(</span>id<span class="token punctuation">,</span> <span class="token keyword">name</span><span class="token punctuation">,</span> <span class="token keyword">path</span><span class="token punctuation">)</span> <span class="token keyword">AS</span>
<span class="token punctuation">(</span>
<span class="token keyword">SELECT</span> id<span class="token punctuation">,</span> <span class="token keyword">name</span><span class="token punctuation">,</span> <span class="token function">CAST</span><span class="token punctuation">(</span>id <span class="token keyword">AS</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">200</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">FROM</span> employees
<span class="token keyword">WHERE</span> manager_id <span class="token operator">IS</span> <span class="token boolean">NULL</span>
<span class="token keyword">UNION</span> <span class="token keyword">ALL</span>
<span class="token keyword">SELECT</span> e<span class="token punctuation">.</span>id<span class="token punctuation">,</span> e<span class="token punctuation">.</span><span class="token keyword">name</span><span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>ep<span class="token punctuation">.</span><span class="token keyword">path</span><span class="token punctuation">,</span> <span class="token string">','</span><span class="token punctuation">,</span> e<span class="token punctuation">.</span>id<span class="token punctuation">)</span>
<span class="token keyword">FROM</span> employee_paths <span class="token keyword">AS</span> ep <span class="token keyword">JOIN</span> employees <span class="token keyword">AS</span> e
<span class="token keyword">ON</span> ep<span class="token punctuation">.</span>id <span class="token operator">=</span> e<span class="token punctuation">.</span>manager_id
<span class="token punctuation">)</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employee_paths <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword">path</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
The CTE produces this output:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa2569499"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">+------+---------+-----------------+
| id | name | path |
+------+---------+-----------------+
| 333 | Yasmina | 333 |
| 198 | John | 333,198 |
| 29 | Pedro | 333,198,29 |
| 4610 | Sarah | 333,198,29,4610 |
| 72 | Pierre | 333,198,29,72 |
| 692 | Tarek | 333,692 |
| 123 | Adil | 333,692,123 |
+------+---------+-----------------+</code></pre>
</div>
<p>
How the CTE works:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The nonrecursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
produces the row for the CEO (the row with a
<code class="literal">
NULL
</code>
manager ID).
</p>
<p>
The
<code class="literal">
path
</code>
column is widened to
<code class="literal">
CHAR(200)
</code>
to ensure that there is room
for the longer
<code class="literal">
path
</code>
values produced by
the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
Each row produced by the recursive
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
finds all employees
who report directly to an employee produced by a previous
row. For each such employee, the row includes the employee
ID and name, and the employee management chain. The chain is
the manager's chain, with the employee ID added to the end.
</p>
</li>
<li class="listitem">
<p>
Recursion ends when employees have no others who report to
them.
</p>
</li>
</ul>
</div>
<p>
To find the path for a specific employee or employees, add a
<code class="literal">
WHERE
</code>
clause to the top-level
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
. For example, to display
the results for Tarek and Sarah, modify that
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3843350"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">WITH</span> <span class="token keyword">RECURSIVE</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees_extended
<span class="token keyword">WHERE</span> id <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token number">692</span><span class="token punctuation">,</span> <span class="token number">4610</span><span class="token punctuation">)</span>
<span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword">path</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> name <span class="token punctuation">|</span> path <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 4610 <span class="token punctuation">|</span> Sarah <span class="token punctuation">|</span> 333,198,29,4610 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 692 <span class="token punctuation">|</span> Tarek <span class="token punctuation">|</span> 333,692 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h4 class="title">
<a name="common-table-expressions-similar-constructs">
</a>
Common Table Expressions Compared to Similar Constructs
</h4>
</div>
</div>
</div>
<p>
Common table expressions (CTEs) are similar to derived tables in
some ways:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Both constructs are named.
</p>
</li>
<li class="listitem">
<p>
Both constructs exist for the scope of a single statement.
</p>
</li>
</ul>
</div>
<p>
Because of these similarities, CTEs and derived tables often can
be used interchangeably. As a trivial example, these statements
are equivalent:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa10390009"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">WITH</span> cte <span class="token keyword">AS</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> cte<span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> dt<span class="token punctuation">;</span></code></pre>
</div>
<p>
However, CTEs have some advantages over derived tables:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
A derived table can be referenced only a single time within
a query. A CTE can be referenced multiple times. To use
multiple instances of a derived table result, you must
derive the result multiple times.
</p>
</li>
<li class="listitem">
<p>
A CTE can be self-referencing (recursive).
</p>
</li>
<li class="listitem">
<p>
One CTE can refer to another.
</p>
</li>
<li class="listitem">
<p>
A CTE may be easier to read when its definition appears at
the beginning of the statement rather than embedded within
it.
</p>
</li>
</ul>
</div>
<p>
CTEs are similar to tables created with
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE [TEMPORARY]
TABLE
</code>
</a>
but need not be defined or dropped explicitly.
For a CTE, you need no privileges to create tables.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/partitioning-selection.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="partitioning-selection">
</a>
26.5 Partition Selection
</h2>
</div>
</div>
</div>
<p>
Explicit selection of partitions and subpartitions for rows
matching a given
<code class="literal">
WHERE
</code>
condition is supported.
Partition selection is similar to partition pruning, in that only
specific partitions are checked for matches, but differs in two
key respects:
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
The partitions to be checked are specified by the issuer of
the statement, unlike partition pruning, which is automatic.
</p>
</li>
<li class="listitem">
<p>
Whereas partition pruning applies only to queries, explicit
selection of partitions is supported for both queries and a
number of DML statements.
</p>
</li>
</ol>
</div>
<p>
SQL statements supporting explicit partition selection are listed
here:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="load-xml.html" title="15.2.10 LOAD XML Statement">
<code class="literal">
LOAD XML
</code>
</a>
.
</p>
</li>
</ul>
</div>
<p>
The remainder of this section discusses explicit partition
selection as it applies generally to the statements just listed,
and provides some examples.
</p>
<p>
Explicit partition selection is implemented using a
<code class="literal">
PARTITION
</code>
option. For all supported statements,
this option uses the syntax shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25190233"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"> <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span><em class="replaceable">partition_names</em><span class="token punctuation">)</span>
<em class="replaceable">partition_names</em>:
<em class="replaceable">partition_name</em><span class="token punctuation">,</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
This option always follows the name of the table to which the
partition or partitions belong.
<em class="replaceable">
<code>
partition_names
</code>
</em>
is a comma-separated
list of partitions or subpartitions to be used. Each name in this
list must be the name of an existing partition or subpartition of
the specified table; if any of the partitions or subpartitions are
not found, the statement fails with an error (
<span class="errortext">
partition
'
<em class="replaceable">
<code>
partition_name
</code>
</em>
' doesn't
exist
</span>
). Partitions and subpartitions named in
<em class="replaceable">
<code>
partition_names
</code>
</em>
may be listed in any
order, and may overlap.
</p>
<p>
When the
<code class="literal">
PARTITION
</code>
option is used, only the
partitions and subpartitions listed are checked for matching rows.
This option can be used in a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement to determine which rows belong to a given partition.
Consider a partitioned table named
<code class="literal">
employees
</code>
,
created and populated using the statements shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa14538669"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@SQL_MODE</span> <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> employees <span class="token punctuation">(</span>
id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
fname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">25</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
lname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">25</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
store_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
department_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span>
<span class="token punctuation">)</span>
<span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">RANGE</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token punctuation">(</span>
<span class="token keyword">PARTITION</span> p0 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token keyword">PARTITION</span> p1 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token keyword">PARTITION</span> p2 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token keyword">PARTITION</span> p3 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token keyword">MAXVALUE</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">VALUES</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Bob'</span><span class="token punctuation">,</span> <span class="token string">'Taylor'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Frank'</span><span class="token punctuation">,</span> <span class="token string">'Williams'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Ellen'</span><span class="token punctuation">,</span> <span class="token string">'Johnson'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Jim'</span><span class="token punctuation">,</span> <span class="token string">'Smith'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Mary'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Linda'</span><span class="token punctuation">,</span> <span class="token string">'Black'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Ed'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'June'</span><span class="token punctuation">,</span> <span class="token string">'Wilson'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Andy'</span><span class="token punctuation">,</span> <span class="token string">'Smith'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Lou'</span><span class="token punctuation">,</span> <span class="token string">'Waters'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Jill'</span><span class="token punctuation">,</span> <span class="token string">'Stone'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Roger'</span><span class="token punctuation">,</span> <span class="token string">'White'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Howard'</span><span class="token punctuation">,</span> <span class="token string">'Andrews'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Fred'</span><span class="token punctuation">,</span> <span class="token string">'Goldberg'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Barbara'</span><span class="token punctuation">,</span> <span class="token string">'Brown'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Alice'</span><span class="token punctuation">,</span> <span class="token string">'Rogers'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Mark'</span><span class="token punctuation">,</span> <span class="token string">'Morgan'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Karen'</span><span class="token punctuation">,</span> <span class="token string">'Cole'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
You can see which rows are stored in partition
<code class="literal">
p1
</code>
like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37629450"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p1<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Mary <span class="token punctuation">|</span> Jones <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> Linda <span class="token punctuation">|</span> Black <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> Ed <span class="token punctuation">|</span> Jones <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> June <span class="token punctuation">|</span> Wilson <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> Andy <span class="token punctuation">|</span> Smith <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">5 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
The result is the same as obtained by the query
<code class="literal">
SELECT *
FROM employees WHERE id BETWEEN 5 AND 9
</code>
.
</p>
<p>
To obtain rows from multiple partitions, supply their names as a
comma-delimited list. For example,
<code class="literal">
SELECT * FROM
employees PARTITION (p1, p2)
</code>
returns all rows from
partitions
<code class="literal">
p1
</code>
and
<code class="literal">
p2
</code>
while
excluding rows from the remaining partitions.
</p>
<p>
Any valid query against a partitioned table can be rewritten with
a
<code class="literal">
PARTITION
</code>
option to restrict the result to
one or more desired partitions. You can use
<code class="literal">
WHERE
</code>
conditions,
<code class="literal">
ORDER BY
</code>
and
<code class="literal">
LIMIT
</code>
options, and so on. You can also use
aggregate functions with
<code class="literal">
HAVING
</code>
and
<code class="literal">
GROUP BY
</code>
options. Each of the following queries
produces a valid result when run on the
<code class="literal">
employees
</code>
table as previously defined:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24963182"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">,</span> p2<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> lname <span class="token operator">LIKE</span> <span class="token string">'S%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Jim <span class="token punctuation">|</span> Smith <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">2 rows in set (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> id<span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>fname<span class="token punctuation">,</span> <span class="token string">' '</span><span class="token punctuation">,</span> lname<span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">name</span>
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">)</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> lname<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> name <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> Ellen Johnson <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Jim Smith <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> Bob Taylor <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> Frank Williams <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">4 rows in set (0.06 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> store_id<span class="token punctuation">,</span> <span class="token function">COUNT</span><span class="token punctuation">(</span>department_id<span class="token punctuation">)</span> <span class="token keyword">AS</span> c
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p1<span class="token punctuation">,</span>p2<span class="token punctuation">,</span>p3<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">GROUP</span> <span class="token keyword">BY</span> store_id <span class="token keyword">HAVING</span> c <span class="token operator">></span> <span class="token number">4</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">2 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
Statements using partition selection can be employed with tables
using any of the supported partitioning types. When a table is
created using
<code class="literal">
[LINEAR] HASH
</code>
or
<code class="literal">
[LINEAR] KEY
</code>
partitioning and the names of the
partitions are not specified, MySQL automatically names the
partitions
<code class="literal">
p0
</code>
,
<code class="literal">
p1
</code>
,
<code class="literal">
p2
</code>
, ...,
<code class="literal">
p
<em class="replaceable">
<code>
N-1
</code>
</em>
</code>
, where
<em class="replaceable">
<code>
N
</code>
</em>
is the number of partitions. For
subpartitions not explicitly named, MySQL assigns automatically to
the subpartitions in each partition
<code class="literal">
p
<em class="replaceable">
<code>
X
</code>
</em>
</code>
the names
<code class="literal">
p
<em class="replaceable">
<code>
X
</code>
</em>
sp0
</code>
,
<code class="literal">
p
<em class="replaceable">
<code>
X
</code>
</em>
sp1
</code>
,
<code class="literal">
p
<em class="replaceable">
<code>
X
</code>
</em>
sp2
</code>
, ...,
<code class="literal">
p
<em class="replaceable">
<code>
X
</code>
</em>
sp
<em class="replaceable">
<code>
M-1
</code>
</em>
</code>
,
where
<em class="replaceable">
<code>
M
</code>
</em>
is the number of subpartitions.
When executing against this table a
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
(or other SQL statement for
which explicit partition selection is allowed), you can use these
generated names in a
<code class="literal">
PARTITION
</code>
option, as shown
here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67093205"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> employees_sub <span class="token punctuation">(</span>
<span class="token prompt"> -></span> id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> fname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">25</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> lname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">25</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> store_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> department_id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> pk <span class="token punctuation">(</span>id<span class="token punctuation">,</span> lname<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">RANGE</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">SUBPARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>lname<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">SUBPARTITIONS</span> <span class="token number">2</span> <span class="token punctuation">(</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p0 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p1 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p2 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p3 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token keyword">MAXVALUE</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (1.14 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees_sub <span class="token comment" spellcheck="true"># reuse data in employees table</span>
<span class="token prompt"> -></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees<span class="token punctuation">;</span>
<span class="token output">Query OK, 18 rows affected (0.09 sec)</span>
<span class="token output">Records: 18 Duplicates: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> id<span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>fname<span class="token punctuation">,</span> <span class="token string">' '</span><span class="token punctuation">,</span> lname<span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">name</span>
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> employees_sub <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p2sp1<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> name <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> Lou Waters <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 14 <span class="token punctuation">|</span> Fred Goldberg <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">2 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
You may also use a
<code class="literal">
PARTITION
</code>
option in the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
portion of an
<a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement">
<code class="literal">
INSERT ...
SELECT
</code>
</a>
statement, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa13454971"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> employees_copy <span class="token operator">LIKE</span> employees<span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.28 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees_copy
<span class="token prompt"> -></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p2<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 5 rows affected (0.04 sec)</span>
<span class="token output">Records: 5 Duplicates: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees_copy<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> Lou <span class="token punctuation">|</span> Waters <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 12 <span class="token punctuation">|</span> Roger <span class="token punctuation">|</span> White <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 13 <span class="token punctuation">|</span> Howard <span class="token punctuation">|</span> Andrews <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 14 <span class="token punctuation">|</span> Fred <span class="token punctuation">|</span> Goldberg <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">5 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
Partition selection can also be used with joins. Suppose we create
and populate two tables using the statements shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa81897609"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> stores <span class="token punctuation">(</span>
id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
city <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">30</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span>
<span class="token punctuation">)</span>
<span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token keyword">PARTITIONS</span> <span class="token number">2</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> stores <span class="token keyword">VALUES</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Nambucca'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Uranga'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Bellingen'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Grafton'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> departments <span class="token punctuation">(</span>
id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
<span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">30</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span>
<span class="token punctuation">)</span>
<span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token keyword">PARTITIONS</span> <span class="token number">2</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> departments <span class="token keyword">VALUES</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Sales'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Customer Service'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Delivery'</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token string">''</span><span class="token punctuation">,</span> <span class="token string">'Accounting'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
You can explicitly select partitions (or subpartitions, or both)
from any or all of the tables in a join. (The
<code class="literal">
PARTITION
</code>
option used to select partitions from
a given table immediately follows the name of the table, before
all other options, including any table alias.) For example, the
following query gets the name, employee ID, department, and city
of all employees who work in the Sales or Delivery department
(partition
<code class="literal">
p1
</code>
of the
<code class="literal">
departments
</code>
table) at the stores in either of
the cities of Nambucca and Bellingen (partition
<code class="literal">
p0
</code>
of the
<code class="literal">
stores
</code>
table):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa55853254"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span>
<span class="token prompt"> -></span> e<span class="token punctuation">.</span>id <span class="token keyword">AS</span> <span class="token string">'Employee ID'</span><span class="token punctuation">,</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>e<span class="token punctuation">.</span>fname<span class="token punctuation">,</span> <span class="token string">' '</span><span class="token punctuation">,</span> e<span class="token punctuation">.</span>lname<span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">Name</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> s<span class="token punctuation">.</span>city <span class="token keyword">AS</span> City<span class="token punctuation">,</span> d<span class="token punctuation">.</span><span class="token keyword">name</span> <span class="token keyword">AS</span> department
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> employees <span class="token keyword">AS</span> e
<span class="token prompt"> -></span> <span class="token keyword">JOIN</span> stores <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p1<span class="token punctuation">)</span> <span class="token keyword">AS</span> s <span class="token keyword">ON</span> e<span class="token punctuation">.</span>store_id<span class="token operator">=</span>s<span class="token punctuation">.</span>id
<span class="token prompt"> -></span> <span class="token keyword">JOIN</span> departments <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">)</span> <span class="token keyword">AS</span> d <span class="token keyword">ON</span> e<span class="token punctuation">.</span>department_id<span class="token operator">=</span>d<span class="token punctuation">.</span>id
<span class="token prompt"> -></span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> e<span class="token punctuation">.</span>lname<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Employee ID <span class="token punctuation">|</span> Name <span class="token punctuation">|</span> City <span class="token punctuation">|</span> department <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 14 <span class="token punctuation">|</span> Fred Goldberg <span class="token punctuation">|</span> Bellingen <span class="token punctuation">|</span> Delivery <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> Mary Jones <span class="token punctuation">|</span> Nambucca <span class="token punctuation">|</span> Sales <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 17 <span class="token punctuation">|</span> Mark Morgan <span class="token punctuation">|</span> Bellingen <span class="token punctuation">|</span> Delivery <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> Andy Smith <span class="token punctuation">|</span> Nambucca <span class="token punctuation">|</span> Delivery <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> June Wilson <span class="token punctuation">|</span> Bellingen <span class="token punctuation">|</span> Sales <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">5 rows in set (0.00 sec)</span></code></pre>
</div>
<p>
For general information about joins in MySQL, see
<a class="xref" href="join.html" title="15.2.13.2 JOIN Clause">
Section 15.2.13.2, “JOIN Clause”
</a>
.
</p>
<p>
When the
<code class="literal">
PARTITION
</code>
option is used with
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statements, only those
partitions (and subpartitions, if any) listed with the option are
checked for rows to be deleted. Any other partitions are ignored,
as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa49782207"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">WHERE</span> fname <span class="token operator">LIKE</span> <span class="token string">'j%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 4 <span class="token punctuation">|</span> Jim <span class="token punctuation">|</span> Smith <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 8 <span class="token punctuation">|</span> June <span class="token punctuation">|</span> Wilson <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">3 rows in set (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">DELETE</span> <span class="token keyword">FROM</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">,</span> p1<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> fname <span class="token operator">LIKE</span> <span class="token string">'j%'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 2 rows affected (0.09 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">WHERE</span> fname <span class="token operator">LIKE</span> <span class="token string">'j%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">1 row in set (0.00 sec)</span></code></pre>
</div>
<p>
Only the two rows in partitions
<code class="literal">
p0
</code>
and
<code class="literal">
p1
</code>
matching the
<code class="literal">
WHERE
</code>
condition were deleted. As you can see from the result when the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
is run a second time, there
remains a row in the table matching the
<code class="literal">
WHERE
</code>
condition, but residing in a different partition
(
<code class="literal">
p2
</code>
).
</p>
<p>
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statements using explicit
partition selection behave in the same way; only rows in the
partitions referenced by the
<code class="literal">
PARTITION
</code>
option
are considered when determining the rows to be updated, as can be
seen by executing the following statements:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa17747091"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">SET</span> store_id <span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">WHERE</span> fname <span class="token operator">=</span> <span class="token string">'Jill'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token output">Rows matched: 0 Changed: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">WHERE</span> fname <span class="token operator">=</span> <span class="token string">'Jill'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">1 row in set (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p2<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">SET</span> store_id <span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">WHERE</span> fname <span class="token operator">=</span> <span class="token string">'Jill'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.09 sec)</span>
<span class="token output">Rows matched: 1 Changed: 1 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> employees <span class="token keyword">WHERE</span> fname <span class="token operator">=</span> <span class="token string">'Jill'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> id <span class="token punctuation">|</span> fname <span class="token punctuation">|</span> lname <span class="token punctuation">|</span> store_id <span class="token punctuation">|</span> department_id <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> Jill <span class="token punctuation">|</span> Stone <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">1 row in set (0.00 sec)</span></code></pre>
</div>
<p>
In the same way, when
<code class="literal">
PARTITION
</code>
is used with
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
, only rows in the partition
or partitions named in the partition list are checked for
deletion.
</p>
<p>
For statements that insert rows, the behavior differs in that
failure to find a suitable partition causes the statement to fail.
This is true for both
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
and
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
statements, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa11020998"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p2<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">,</span> <span class="token string">'Jan'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1729 (HY000)<span class="token punctuation">:</span> Found a row not matching the given partition set</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p3<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">,</span> <span class="token string">'Jan'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.07 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">REPLACE</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p0<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">,</span> <span class="token string">'Jan'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1729 (HY000)<span class="token punctuation">:</span> Found a row not matching the given partition set
</span>
<span class="token prompt">mysql></span> <span class="token keyword">REPLACE</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p3<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">,</span> <span class="token string">'Jan'</span><span class="token punctuation">,</span> <span class="token string">'Jones'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 2 rows affected (0.09 sec)</span></code></pre>
</div>
<p>
For statements that write multiple rows to a partitioned table
that using the
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
storage engine:
If any row in the list following
<code class="literal">
VALUES
</code>
cannot
be written to one of the partitions specified in the
<em class="replaceable">
<code>
partition_names
</code>
</em>
list, the entire
statement fails and no rows are written. This is shown for
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements in the following
example, reusing the
<code class="literal">
employees
</code>
table created
previously:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa43978087"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> employees
<span class="token prompt"> -></span> <span class="token keyword">REORGANIZE</span> <span class="token keyword">PARTITION</span> p3 <span class="token keyword">INTO</span> <span class="token punctuation">(</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p3 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p4 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">25</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p5 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token keyword">MAXVALUE</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 6 rows affected (2.09 sec)</span>
<span class="token output">Records: 6 Duplicates: 0 Warnings: 0</span>
<span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> employees\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Table<span class="token punctuation">:</span> employees
Create Table<span class="token punctuation">:</span> CREATE TABLE `employees` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`fname` varchar(25) NOT NULL,
`lname` varchar(25) NOT NULL,
`store_id` int(11) NOT NULL,
`department_id` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/<span class="token punctuation">*</span>!50100 PARTITION BY RANGE (id)
(PARTITION p0 VALUES LESS THAN (5) ENGINE = InnoDB,
PARTITION p1 VALUES LESS THAN (10) ENGINE = InnoDB,
PARTITION p2 VALUES LESS THAN (15) ENGINE = InnoDB,
PARTITION p3 VALUES LESS THAN (20) ENGINE = InnoDB,
PARTITION p4 VALUES LESS THAN (25) ENGINE = InnoDB,
PARTITION p5 VALUES LESS THAN MAXVALUE ENGINE = InnoDB) <span class="token punctuation">*</span>/
</span><span class="token output">1 row in set (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p3<span class="token punctuation">,</span> p4<span class="token punctuation">)</span> <span class="token keyword">VALUES</span>
<span class="token prompt"> -></span> <span class="token punctuation">(</span><span class="token number">24</span><span class="token punctuation">,</span> <span class="token string">'Tim'</span><span class="token punctuation">,</span> <span class="token string">'Greene'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">,</span> <span class="token string">'Linda'</span><span class="token punctuation">,</span> <span class="token string">'Mills'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1729 (HY000)<span class="token punctuation">:</span> Found a row not matching the given partition set
</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> employees <span class="token keyword">PARTITION</span> <span class="token punctuation">(</span>p3<span class="token punctuation">,</span> p4<span class="token punctuation">,</span> p5<span class="token punctuation">)</span> <span class="token keyword">VALUES</span>
<span class="token prompt"> -></span> <span class="token punctuation">(</span><span class="token number">24</span><span class="token punctuation">,</span> <span class="token string">'Tim'</span><span class="token punctuation">,</span> <span class="token string">'Greene'</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token number">26</span><span class="token punctuation">,</span> <span class="token string">'Linda'</span><span class="token punctuation">,</span> <span class="token string">'Mills'</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 2 rows affected (0.06 sec)</span>
<span class="token output">Records: 2 Duplicates: 0 Warnings: 0</span></code></pre>
</div>
<p>
The preceding is true for both
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
statements and
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
statements that write
multiple rows.
</p>
<p>
Partition selection is disabled for tables employing a storage
engine that supplies automatic partitioning, such as
<code class="literal">
NDB
</code>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-solutions-rbr-monitoring.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="replication-solutions-rbr-monitoring">
</a>
19.4.3 Monitoring Row-based Replication
</h3>
</div>
</div>
</div>
<p>
The current progress of the replication applier (SQL) thread when
using row-based replication is monitored through Performance
Schema instrument stages, enabling you to track the processing of
operations and check the amount of work completed and work
estimated. When these Performance Schema instrument stages are
enabled the
<a class="link" href="performance-schema-events-stages-current-table.html" title="29.12.5.1 The events_stages_current Table">
<code class="literal">
events_stages_current
</code>
</a>
table shows stages for applier threads and their progress. For
background information, see
<a class="xref" href="performance-schema-stage-tables.html" title="29.12.5 Performance Schema Stage Event Tables">
Section 29.12.5, “Performance Schema Stage Event Tables”
</a>
.
</p>
<p>
To track progress of all three row-based replication event types
(write, update, delete):
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Enable the three Performance Schema stages by issuing:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa11639495"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> performance_schema<span class="token punctuation">.</span>setup_instruments <span class="token keyword">SET</span> ENABLED <span class="token operator">=</span> <span class="token string">'YES'</span>
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> <span class="token keyword">NAME</span> <span class="token operator">LIKE</span> <span class="token string">'stage/sql/Applying batch of row changes%'</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Wait for some events to be processed by the replication
applier thread and then check progress by looking into the
<a class="link" href="performance-schema-events-stages-current-table.html" title="29.12.5.1 The events_stages_current Table">
<code class="literal">
events_stages_current
</code>
</a>
table. For
example to get progress for
<code class="literal">
update
</code>
events
issue:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47589566"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> WORK_COMPLETED<span class="token punctuation">,</span> WORK_ESTIMATED <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>events_stages_current
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> EVENT_NAME <span class="token operator">LIKE</span> <span class="token string">'stage/sql/Applying batch of row changes (update)'</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
If
<a class="link" href="replication-options-binary-log.html#sysvar_binlog_rows_query_log_events">
<code class="literal">
binlog_rows_query_log_events
</code>
</a>
is enabled, information about queries is stored in the binary
log and is exposed in the
<code class="literal">
processlist_info
</code>
field. To see the original query that triggered this event:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78733572"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> db<span class="token punctuation">,</span> processlist_state<span class="token punctuation">,</span> processlist_info <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>threads
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> processlist_state <span class="token operator">LIKE</span> <span class="token string">'stage/sql/Applying batch of row changes%'</span> <span class="token operator">AND</span> thread_id <span class="token operator">=</span> N<span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/create-tablespace.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="create-tablespace">
</a>
15.1.21 CREATE TABLESPACE Statement
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045184130736">
</a>
<a class="indexterm" name="idm46045184129696">
</a>
<a class="indexterm" name="idm46045184128208">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69936528"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token punctuation">[</span><span class="token keyword">UNDO</span><span class="token punctuation">]</span> <span class="token keyword">TABLESPACE</span> <em class="replaceable">tablespace_name</em>
<em>InnoDB <span class="token operator">and</span> <span class="token keyword">NDB</span>:</em>
<span class="token punctuation">[</span><span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'<em class="replaceable">file_name</em>'</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">AUTOEXTEND_SIZE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token keyword"><em class="replaceable">value</em></span><span class="token punctuation">]</span>
<em>InnoDB <span class="token keyword">only</span>:</em>
<span class="token punctuation">[</span><span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token keyword">value</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">ENCRYPTION</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> {<span class="token string">'Y'</span> <span class="token operator">|</span> <span class="token string">'N'</span>}<span class="token punctuation">]</span>
<span class="token keyword"></span><em><span class="token keyword">NDB</span> <span class="token keyword">only</span>:</em>
<span class="token keyword">USE</span> <span class="token keyword">LOGFILE</span> <span class="token keyword">GROUP</span> <em class="replaceable">logfile_group</em>
<span class="token punctuation">[</span><span class="token keyword">EXTENT_SIZE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token keyword"><em class="replaceable">extent_size</em></span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">INITIAL_SIZE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token keyword"><em class="replaceable">initial_size</em></span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">MAX_SIZE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token keyword"><em class="replaceable">max_size</em></span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">NODEGROUP</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">nodegroup_id</em><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">WAIT</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span><span class="token keyword">COMMENT</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token string">'<em class="replaceable">string</em>'</span><span class="token punctuation">]</span>
<em>InnoDB <span class="token operator">and</span> <span class="token keyword">NDB</span>:</em>
<span class="token punctuation">[</span><span class="token keyword">ENGINE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">engine_name</em><span class="token punctuation">]</span>
<em>Reserved <span class="token keyword">for</span> future <span class="token keyword">use</span>:</em>
<span class="token punctuation">[</span><span class="token keyword">ENGINE_ATTRIBUTE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <span class="token string">'<em class="replaceable">string</em>'</span><span class="token punctuation">]</span></code></pre>
</div>
<p>
This statement is used to create a tablespace. The precise syntax
and semantics depend on the storage engine used. In standard MySQL
releases, this is always an
<a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine">
<code class="literal">
InnoDB
</code>
</a>
tablespace. MySQL NDB Cluster also supports tablespaces using the
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
storage engine.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-innodb" title="Considerations for InnoDB">
Considerations for InnoDB
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-ndb" title="Considerations for NDB Cluster">
Considerations for NDB Cluster
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-options" title="Options">
Options
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-notes" title="Notes">
Notes
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-innodb-examples" title="InnoDB Examples">
InnoDB Examples
</a>
</p>
</li>
<li class="listitem">
<p>
<a class="xref" href="create-tablespace.html#create-tablespace-ndb-examples" title="NDB Example">
NDB Example
</a>
</p>
</li>
</ul>
</div>
<h4>
<a name="create-tablespace-innodb">
</a>
Considerations for InnoDB
</h4>
<p>
<a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement">
<code class="literal">
CREATE TABLESPACE
</code>
</a>
syntax is used to
create general tablespaces or undo tablespaces. The
<code class="literal">
UNDO
</code>
keyword must be specified to create an
undo tablespace.
</p>
<p>
A general tablespace is a shared tablespace. It can hold multiple
tables, and supports all table row formats. General tablespaces
can be created in a location relative to or independent of the
data directory.
</p>
<p>
After creating an
<code class="literal">
InnoDB
</code>
general tablespace,
use
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
<em class="replaceable">
<code>
tbl_name
</code>
</em>
... TABLESPACE [=]
<em class="replaceable">
<code>
tablespace_name
</code>
</em>
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
<em class="replaceable">
<code>
tbl_name
</code>
</em>
TABLESPACE [=]
<em class="replaceable">
<code>
tablespace_name
</code>
</em>
</code>
</a>
to add tables
to the tablespace. For more information, see
<a class="xref" href="general-tablespaces.html" title="17.6.3.3 General Tablespaces">
Section 17.6.3.3, “General Tablespaces”
</a>
.
</p>
<p>
Undo tablespaces contain undo logs. Undo tablespaces can be
created in a chosen location by specifying a fully qualified data
file path. For more information, see
<a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces">
Section 17.6.3.4, “Undo Tablespaces”
</a>
.
</p>
<h4>
<a name="create-tablespace-ndb">
</a>
Considerations for NDB Cluster
</h4>
<p>
This statement is used to create a tablespace, which can contain
one or more data files, providing storage space for NDB Cluster
Disk Data tables (see
<a class="xref" href="mysql-cluster-disk-data.html" title="25.6.11 NDB Cluster Disk Data Tables">
Section 25.6.11, “NDB Cluster Disk Data Tables”
</a>
).
One data file is created and added to the tablespace using this
statement. Additional data files may be added to the tablespace by
using the
<a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
<code class="literal">
ALTER TABLESPACE
</code>
</a>
statement (see
<a class="xref" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
Section 15.1.10, “ALTER TABLESPACE Statement”
</a>
).
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
All NDB Cluster Disk Data objects share the same namespace. This
means that
<span class="emphasis">
<em>
each Disk Data object
</em>
</span>
must be
uniquely named (and not merely each Disk Data object of a given
type). For example, you cannot have a tablespace and a log file
group with the same name, or a tablespace and a data file with
the same name.
</p>
</div>
<p>
A log file group of one or more
<code class="literal">
UNDO
</code>
log files
must be assigned to the tablespace to be created with the
<code class="literal">
USE LOGFILE GROUP
</code>
clause.
<em class="replaceable">
<code>
logfile_group
</code>
</em>
must be an existing log
file group created with
<a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement">
<code class="literal">
CREATE LOGFILE
GROUP
</code>
</a>
(see
<a class="xref" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement">
Section 15.1.16, “CREATE LOGFILE GROUP Statement”
</a>
).
Multiple tablespaces may use the same log file group for
<code class="literal">
UNDO
</code>
logging.
</p>
<p>
When setting
<code class="literal">
EXTENT_SIZE
</code>
or
<code class="literal">
INITIAL_SIZE
</code>
, you may optionally follow the
number with a one-letter abbreviation for an order of magnitude,
similar to those used in
<code class="filename">
my.cnf
</code>
. Generally,
this is one of the letters
<code class="literal">
M
</code>
(for megabytes) or
<code class="literal">
G
</code>
(for gigabytes).
</p>
<p>
<code class="literal">
INITIAL_SIZE
</code>
and
<code class="literal">
EXTENT_SIZE
</code>
are subject to rounding as follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
EXTENT_SIZE
</code>
is rounded up to the nearest
whole multiple of 32K.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
INITIAL_SIZE
</code>
is rounded
<span class="emphasis">
<em>
down
</em>
</span>
to the nearest whole multiple of
32K; this result is rounded up to the nearest whole multiple
of
<code class="literal">
EXTENT_SIZE
</code>
(after any rounding).
</p>
</li>
</ul>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
<a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
<code class="literal">
NDB
</code>
</a>
reserves 4% of a tablespace for
data node restart operations. This reserved space cannot be used
for data storage.
</p>
</div>
<p>
The rounding just described is done explicitly, and a warning is
issued by the MySQL Server when any such rounding is performed.
The rounded values are also used by the NDB kernel for calculating
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
INFORMATION_SCHEMA.FILES
</code>
</a>
column
values and other purposes. However, to avoid an unexpected result,
we suggest that you always use whole multiples of 32K in
specifying these options.
</p>
<p>
When
<a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement">
<code class="literal">
CREATE TABLESPACE
</code>
</a>
is used with
<code class="literal">
ENGINE [=] NDB
</code>
, a tablespace and associated
data file are created on each Cluster data node. You can verify
that the data files were created and obtain information about them
by querying the Information Schema
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
FILES
</code>
</a>
table. (See the example later
in this section.)
</p>
<p>
(See
<a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
Section 28.3.15, “The INFORMATION_SCHEMA FILES Table”
</a>
.)
</p>
<h4>
<a name="create-tablespace-options">
</a>
Options
</h4>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
ADD DATAFILE
</code>
: Defines the name of a
tablespace data file. This option is always required when
creating an
<code class="literal">
NDB
</code>
tablespace; for
<code class="literal">
InnoDB
</code>
, it is required only when creating
an undo tablespace. The
<code class="literal">
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
,
including any specified path, must be quoted with single or
double quotation marks. File names (not counting the file
extension) and directory names must be at least one byte in
length. Zero length file names and directory names are not
supported.
</p>
<p>
Because there are considerable differences in how
<code class="literal">
InnoDB
</code>
and
<code class="literal">
NDB
</code>
treat
data files, the two storage engines are covered separately in
the discussion that follows.
</p>
<p>
<b>
InnoDB data files.
</b>
An
<code class="literal">
InnoDB
</code>
tablespace supports only a
single data file, whose name must include an
<code class="filename">
.ibd
</code>
extension.
</p>
<p>
To place an
<code class="literal">
InnoDB
</code>
general tablespace data
file in a location outside of the data directory, include a
fully qualified path or a path relative to the data directory.
Only a fully qualified path is permitted for undo tablespaces.
If you do not specify a path, a general tablespace is created
in the data directory. An undo tablespace created without
specifying a path is created in the directory defined by the
<a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory">
<code class="literal">
innodb_undo_directory
</code>
</a>
variable. If
<code class="literal">
innodb_undo_directory
</code>
is not
set, undo tablespaces are created in the data directory.
</p>
<p>
To avoid conflicts with implicitly created file-per-table
tablespaces, creating an
<code class="literal">
InnoDB
</code>
general
tablespace in a subdirectory under the data directory is not
supported. When creating a general tablespace or undo
tablespace outside of the data directory, the directory must
exist and must be known to
<code class="literal">
InnoDB
</code>
prior to
creating the tablespace. To make a directory known to
<code class="literal">
InnoDB
</code>
, add it to the
<a class="link" href="innodb-parameters.html#sysvar_innodb_directories">
<code class="literal">
innodb_directories
</code>
</a>
value or
to one of the variables whose values are appended to the value
of
<code class="literal">
innodb_directories
</code>
.
<code class="literal">
innodb_directories
</code>
is a read-only variable.
Configuring it requires restarting the server.
</p>
<p>
If the
<code class="literal">
ADD DATAFILE
</code>
clause is not specified
when creating an
<code class="literal">
InnoDB
</code>
tablespace, a
tablespace data file with a unique file name is created
implicitly. The unique file name is a 128 bit UUID formatted
into five groups of hexadecimal numbers separated by dashes
(
<em class="replaceable">
<code>
aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee
</code>
</em>
).
A file extension is added if required by the storage engine.
An
<code class="filename">
.ibd
</code>
file extension is added for
<code class="literal">
InnoDB
</code>
general tablespace data files. In a
replication environment, the data file name created on the
replication source server is not the same as the data file
name created on the replica.
</p>
<p>
The
<code class="literal">
ADD DATAFILE
</code>
clause does not permit
circular directory references when creating an
<code class="literal">
InnoDB
</code>
tablespace. For example, the
circular directory reference (
<code class="literal">
/../
</code>
) in the
following statement is not permitted:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa4055276"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> ts1<span class="token punctuation">.</span>ibd <span class="token string">'<em class="replaceable">any_directory</em>/../ts1.ibd'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
An exception to this restriction exists on Linux, where a
circular directory reference is permitted if the preceding
directory is a symbolic link. For example, the data file path
in the example above is permitted if
<em class="replaceable">
<code>
any_directory
</code>
</em>
is a symbolic link.
(It is still permitted for data file paths to begin with
'
<code class="literal">
../
</code>
'.)
</p>
<p>
<b>
NDB data files.
</b>
An
<code class="literal">
NDB
</code>
tablespace supports multiple data
files which can have any legal file names; more data files
can be added to an NDB Cluster tablespace following its
creation by using an
<a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
<code class="literal">
ALTER
TABLESPACE
</code>
</a>
statement.
</p>
<p>
An
<code class="literal">
NDB
</code>
tablespace data file is created by
default in the data node file system directory—that is,
the directory named
<code class="filename">
ndb_
<em class="replaceable">
<code>
nodeid
</code>
</em>
_fs/TS
</code>
under the data node's data directory
(
<a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datadir">
<code class="literal">
DataDir
</code>
</a>
), where
<em class="replaceable">
<code>
nodeid
</code>
</em>
is the data node's
<a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-nodeid">
<code class="literal">
NodeId
</code>
</a>
. To place the
data file in a location other than the default, include an
absolute directory path or a path relative to the default
location. If the directory specified does not exist,
<code class="literal">
NDB
</code>
attempts to create it; the system user
account under which the data node process is running must have
the appropriate permissions to do so.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
When determining the path used for a data file,
<code class="literal">
NDB
</code>
does not expand the
<code class="literal">
~
</code>
(tilde) character.
</p>
</div>
<p>
When multiple data nodes are run on the same physical host,
the following considerations apply:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
You cannot specify an absolute path when creating a data
file.
</p>
</li>
<li class="listitem">
<p>
It is not possible to create tablespace data files outside
the data node file system directory, unless each data node
has a separate data directory.
</p>
</li>
<li class="listitem">
<p>
If each data node has its own data directory, data files
can be created anywhere within this directory.
</p>
</li>
<li class="listitem">
<p>
If each data node has its own data directory, it may also
be possible to create a data file outside the node's
data directory using a relative path, as long as this path
resolves to a unique location on the host file system for
each data node running on that host.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
<code class="literal">
FILE_BLOCK_SIZE
</code>
: This option—which is
specific to
<code class="literal">
InnoDB
</code>
general tablespaces, and
is ignored by
<code class="literal">
NDB
</code>
—defines the block
size for the tablespace data file. Values can be specified in
bytes or kilobytes. For example, an 8 kilobyte file block size
can be specified as 8192 or 8K. If you do not specify this
option,
<code class="literal">
FILE_BLOCK_SIZE
</code>
defaults to the
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
value.
<code class="literal">
FILE_BLOCK_SIZE
</code>
is required when you intend
to use the tablespace for storing compressed
<code class="literal">
InnoDB
</code>
tables
(
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
). In this case, you
must define the tablespace
<code class="literal">
FILE_BLOCK_SIZE
</code>
when creating the tablespace.
</p>
<p>
If
<code class="literal">
FILE_BLOCK_SIZE
</code>
is equal the
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
value, the
tablespace can contain only tables having an uncompressed row
format (
<code class="literal">
COMPACT
</code>
,
<code class="literal">
REDUNDANT
</code>
, and
<code class="literal">
DYNAMIC
</code>
).
Tables with a
<code class="literal">
COMPRESSED
</code>
row format have a
different physical page size than uncompressed tables.
Therefore, compressed tables cannot coexist in the same
tablespace as uncompressed tables.
</p>
<p>
For a general tablespace to contain compressed tables,
<code class="literal">
FILE_BLOCK_SIZE
</code>
must be specified, and the
<code class="literal">
FILE_BLOCK_SIZE
</code>
value must be a valid
compressed page size in relation to the
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
value. Also,
the physical page size of the compressed table
(
<code class="literal">
KEY_BLOCK_SIZE
</code>
) must be equal to
<code class="literal">
FILE_BLOCK_SIZE/1024
</code>
. For example, if
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size=16K
</code>
</a>
, and
<code class="literal">
FILE_BLOCK_SIZE=8K
</code>
, the
<code class="literal">
KEY_BLOCK_SIZE
</code>
of the table must be 8. For
more information, see
<a class="xref" href="general-tablespaces.html" title="17.6.3.3 General Tablespaces">
Section 17.6.3.3, “General Tablespaces”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
USE LOGFILE GROUP
</code>
: Required for
<code class="literal">
NDB
</code>
, this is the name of a log file group
previously created using
<a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement">
<code class="literal">
CREATE LOGFILE
GROUP
</code>
</a>
. Not supported for
<code class="literal">
InnoDB
</code>
,
where it fails with an error.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
EXTENT_SIZE
</code>
: This option is specific to
NDB, and is not supported by InnoDB, where it fails with an
error.
<code class="literal">
EXTENT_SIZE
</code>
sets the size, in bytes,
of the extents used by any files belonging to the tablespace.
The default value is 1M. The minimum size is 32K, and
theoretical maximum is 2G, although the practical maximum size
depends on a number of factors. In most cases, changing the
extent size does not have any measurable effect on
performance, and the default value is recommended for all but
the most unusual situations.
</p>
<p>
An
<span class="firstterm">
extent
</span>
is a unit of
disk space allocation. One extent is filled with as much data
as that extent can contain before another extent is used. In
theory, up to 65,535 (64K) extents may used per data file;
however, the recommended maximum is 32,768 (32K). The
recommended maximum size for a single data file is
32G—that is, 32K extents × 1 MB per extent. In
addition, once an extent is allocated to a given partition, it
cannot be used to store data from a different partition; an
extent cannot store data from more than one partition. This
means, for example that a tablespace having a single datafile
whose
<code class="literal">
INITIAL_SIZE
</code>
(described in the
following item) is 256 MB and whose
<code class="literal">
EXTENT_SIZE
</code>
is 128M has just two extents,
and so can be used to store data from at most two different
disk data table partitions.
</p>
<p>
You can see how many extents remain free in a given data file
by querying the Information Schema
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
FILES
</code>
</a>
table, and so derive an
estimate for how much space remains free in the file. For
further discussion and examples, see
<a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
Section 28.3.15, “The INFORMATION_SCHEMA FILES Table”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
INITIAL_SIZE
</code>
: This option is specific to
<code class="literal">
NDB
</code>
, and is not supported by
<code class="literal">
InnoDB
</code>
, where it fails with an error.
</p>
<p>
The
<code class="literal">
INITIAL_SIZE
</code>
parameter sets the total
size in bytes of the data file that was specific using
<code class="literal">
ADD DATATFILE
</code>
. Once this file has been
created, its size cannot be changed; however, you can add more
data files to the tablespace using
<a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
<code class="literal">
ALTER
TABLESPACE ... ADD DATAFILE
</code>
</a>
.
</p>
<p>
<code class="literal">
INITIAL_SIZE
</code>
is optional; its default value
is 134217728 (128 MB).
</p>
<p>
On 32-bit systems, the maximum supported value for
<code class="literal">
INITIAL_SIZE
</code>
is 4294967296 (4 GB).
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
AUTOEXTEND_SIZE
</code>
: Defines the amount by
which
<code class="literal">
InnoDB
</code>
extends the size of the
tablespace when it becomes full. The setting must be a
multiple of 4MB. The default setting is 0, which causes the
tablespace to be extended according to the implicit default
behavior. For more information, see
<a class="xref" href="innodb-tablespace-autoextend-size.html" title="17.6.3.9 Tablespace AUTOEXTEND_SIZE Configuration">
Section 17.6.3.9, “Tablespace AUTOEXTEND_SIZE Configuration”
</a>
.
</p>
<p>
Has no effect in any release of MySQL NDB Cluster, regardless
of the storage engine used.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
MAX_SIZE
</code>
: Currently ignored by MySQL;
reserved for possible future use. Has no effect in any release
of MySQL or MySQL NDB Cluster, regardless of the storage
engine used.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
NODEGROUP
</code>
: Currently ignored by MySQL;
reserved for possible future use. Has no effect in any release
of MySQL or MySQL NDB Cluster, regardless of the storage
engine used.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
WAIT
</code>
: Currently ignored by MySQL; reserved
for possible future use. Has no effect in any release of MySQL
or MySQL NDB Cluster, regardless of the storage engine used.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
COMMENT
</code>
: Currently ignored by MySQL;
reserved for possible future use. Has no effect in any release
of MySQL or MySQL NDB Cluster, regardless of the storage
engine used.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
ENCRYPTION
</code>
clause enables or disables
page-level data encryption for an
<code class="literal">
InnoDB
</code>
general tablespace.
</p>
<p>
If the
<code class="literal">
ENCRYPTION
</code>
clause is not specified,
the
<a class="link" href="server-system-variables.html#sysvar_default_table_encryption">
<code class="literal">
default_table_encryption
</code>
</a>
setting controls whether encryption is enabled. The
<code class="literal">
ENCRYPTION
</code>
clause overrides the
<a class="link" href="server-system-variables.html#sysvar_default_table_encryption">
<code class="literal">
default_table_encryption
</code>
</a>
setting. However, if the
<a class="link" href="server-system-variables.html#sysvar_table_encryption_privilege_check">
<code class="literal">
table_encryption_privilege_check
</code>
</a>
variable is enabled, the
<a class="link" href="privileges-provided.html#priv_table-encryption-admin">
<code class="literal">
TABLE_ENCRYPTION_ADMIN
</code>
</a>
privilege is required to use an
<code class="literal">
ENCRYPTION
</code>
clause setting that differs from the
<a class="link" href="server-system-variables.html#sysvar_default_table_encryption">
<code class="literal">
default_table_encryption
</code>
</a>
setting.
</p>
<p>
A keyring plugin must be installed and configured before an
encryption-enabled tablespace can be created.
</p>
<p>
When a general tablespace is encrypted, all tables residing in
the tablespace are encrypted. Likewise, a table created in an
encrypted tablespace is encrypted.
</p>
<p>
For more information, see
<a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption">
Section 17.13, “InnoDB Data-at-Rest Encryption”
</a>
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ENGINE
</code>
: Defines the storage engine which
uses the tablespace, where
<em class="replaceable">
<code>
engine_name
</code>
</em>
is the name of the
storage engine. Currently, only the
<code class="literal">
InnoDB
</code>
storage engine is supported by standard MySQL 8.4
releases. MySQL NDB Cluster supports both
<code class="literal">
NDB
</code>
and
<code class="literal">
InnoDB
</code>
tablespaces. The value of the
<a class="link" href="server-system-variables.html#sysvar_default_storage_engine">
<code class="literal">
default_storage_engine
</code>
</a>
system
variable is used for
<code class="literal">
ENGINE
</code>
if the option
is not specified.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
ENGINE_ATTRIBUTE
</code>
option is used to
specify tablespace attributes for primary storage engines. The
option is reserved for future use.
</p>
<p>
The value assigned to this option must be a string literal
containing a valid JSON document or an empty string ('').
Invalid JSON is rejected.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa4405257"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ENGINE_ATTRIBUTE</span><span class="token operator">=</span><span class="token string">'{"<em class="replaceable">key</em>":"<em class="replaceable">value</em>"}'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
<code class="literal">
ENGINE_ATTRIBUTE
</code>
values can be repeated
without error. In this case, the last specified value is used.
</p>
<p>
<code class="literal">
ENGINE_ATTRIBUTE
</code>
values are not checked by
the server, nor are they cleared when the table's storage
engine is changed.
</p>
</li>
</ul>
</div>
<h4>
<a name="create-tablespace-notes">
</a>
Notes
</h4>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
For the rules covering the naming of MySQL tablespaces, see
<a class="xref" href="identifiers.html" title="11.2 Schema Object Names">
Section 11.2, “Schema Object Names”
</a>
. In addition to these rules, the
slash character (
<span class="quote">
“
<span class="quote">
/
</span>
”
</span>
) is not permitted, nor can
you use names beginning with
<code class="literal">
innodb_
</code>
, as
this prefix is reserved for system use.
</p>
</li>
<li class="listitem">
<p>
Creation of temporary general tablespaces is not supported.
</p>
</li>
<li class="listitem">
<p>
General tablespaces do not support temporary tables.
</p>
</li>
<li class="listitem">
<p>
The
<code class="literal">
TABLESPACE
</code>
option may be used with
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
to assign an
<code class="literal">
InnoDB
</code>
table partition or subpartition to a
file-per-table tablespace. All partitions must belong to the
same storage engine. Assigning table partitions to shared
<code class="literal">
InnoDB
</code>
tablespaces is not supported. Shared
tablespaces include the
<code class="literal">
InnoDB
</code>
system
tablespace and general tablespaces.
</p>
</li>
<li class="listitem">
<p>
General tablespaces support the addition of tables of any row
format using
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE ...
TABLESPACE
</code>
</a>
.
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
does
not need to be enabled.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is not
applicable to general tablespaces. Tablespace management rules
are strictly enforced independently of
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
. If
<code class="literal">
CREATE TABLESPACE
</code>
parameters are incorrect
or incompatible, the operation fails regardless of the
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
setting.
When a table is added to a general tablespace using
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE ...
TABLESPACE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE ...
TABLESPACE
</code>
</a>
,
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is ignored
but the statement is evaluated as if
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is
enabled.
</p>
</li>
<li class="listitem">
<p>
Use
<code class="literal">
DROP TABLESPACE
</code>
to remove a tablespace.
All tables must be dropped from a tablespace using
<a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
<code class="literal">
DROP TABLE
</code>
</a>
prior to dropping
the tablespace. Before dropping an NDB Cluster tablespace you
must also remove all its data files using one or more
<a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement">
<code class="literal">
ALTER
TABLESPACE ... DROP DATATFILE
</code>
</a>
statements. See
<a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects">
Section 25.6.11.1, “NDB Cluster Disk Data Objects”
</a>
.
</p>
</li>
<li class="listitem">
<p>
All parts of an
<code class="literal">
InnoDB
</code>
table added to an
<code class="literal">
InnoDB
</code>
general tablespace reside in the
general tablespace, including indexes and
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
BLOB
</code>
</a>
pages.
</p>
<p>
For an
<code class="literal">
NDB
</code>
table assigned to a tablespace,
only those columns which are not indexed are stored on disk,
and actually use the tablespace data files. Indexes and
indexed columns for all
<code class="literal">
NDB
</code>
tables are
always kept in memory.
</p>
</li>
<li class="listitem">
<p>
Similar to the system tablespace, truncating or dropping
tables stored in a general tablespace creates free space
internally in the general tablespace
<a class="link" href="glossary.html#glos_ibd_file" title=".ibd file">
.ibd data file
</a>
which can
only be used for new
<code class="literal">
InnoDB
</code>
data. Space is
not released back to the operating system as it is for
file-per-table tablespaces.
</p>
</li>
<li class="listitem">
<p>
A general tablespace is not associated with any database or
schema.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE ...
DISCARD TABLESPACE
</code>
</a>
and
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
...IMPORT TABLESPACE
</code>
</a>
are not supported for tables
that belong to a general tablespace.
</p>
</li>
<li class="listitem">
<p>
The server uses tablespace-level metadata locking for DDL that
references general tablespaces. By comparison, the server uses
table-level metadata locking for DDL that references
file-per-table tablespaces.
</p>
</li>
<li class="listitem">
<p>
A generated or existing tablespace cannot be changed to a
general tablespace.
</p>
</li>
<li class="listitem">
<p>
There is no conflict between general tablespace names and
file-per-table tablespace names. The
<span class="quote">
“
<span class="quote">
/
</span>
”
</span>
character, which is present in file-per-table tablespace
names, is not permitted in general tablespace names.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
does not dump
<code class="literal">
InnoDB
</code>
<a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement">
<code class="literal">
CREATE
TABLESPACE
</code>
</a>
statements.
</p>
</li>
</ul>
</div>
<h4>
<a name="create-tablespace-innodb-examples">
</a>
InnoDB Examples
</h4>
<p>
This example demonstrates creating a general tablespace and adding
three uncompressed tables of different row formats.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa15168896"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>INNODB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">REDUNDANT</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPACT</span><span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">DYNAMIC</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This example demonstrates creating a general tablespace and adding
a compressed table. The example assumes a default
<a class="link" href="innodb-parameters.html#sysvar_innodb_page_size">
<code class="literal">
innodb_page_size
</code>
</a>
value of 16K.
The
<code class="literal">
FILE_BLOCK_SIZE
</code>
of 8192 requires that the
compressed table have a
<code class="literal">
KEY_BLOCK_SIZE
</code>
of 8.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa95626162"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts2<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts2.ibd'</span> <span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token number">8192</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t4 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts2 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPRESSED</span> <span class="token keyword">KEY_BLOCK_SIZE</span><span class="token operator">=</span><span class="token number">8</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
This example demonstrates creating a general tablespace without
specifying the
<code class="literal">
ADD DATAFILE
</code>
clause, which is
optional:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa7786188"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts3<span class="token punctuation">`</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>INNODB<span class="token punctuation">;</span></code></pre>
</div>
<p>
This example demonstrates creating an undo tablespace:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa12847076"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">UNDO</span> <span class="token keyword">TABLESPACE</span> <em class="replaceable">undo_003</em> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'<em class="replaceable">undo_003</em>.ibu'</span><span class="token punctuation">;</span></code></pre>
</div>
<h4>
<a name="create-tablespace-ndb-examples">
</a>
NDB Example
</h4>
<p>
Suppose that you wish to create an NDB Cluster Disk Data
tablespace named
<code class="literal">
myts
</code>
using a datafile named
<code class="filename">
mydata-1.dat
</code>
. An
<code class="filename">
NDB
</code>
tablespace always requires the use of a log file group consisting
of one or more undo log files. For this example, we first create a
log file group named
<code class="literal">
mylg
</code>
that contains one
undo long file named
<code class="filename">
myundo-1.dat
</code>
, using the
<a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement">
<code class="literal">
CREATE LOGFILE GROUP
</code>
</a>
statement
shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28439111"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">LOGFILE</span> <span class="token keyword">GROUP</span> myg1
<span class="token prompt"> -></span> <span class="token keyword">ADD</span> <span class="token keyword">UNDOFILE</span> <span class="token string">'myundo-1.dat'</span>
<span class="token prompt"> -></span> <span class="token keyword">ENGINE</span><span class="token operator">=</span><span class="token keyword">NDB</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (3.29 sec)</span></code></pre>
</div>
<p>
Now you can create the tablespace previously described using the
following statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47420122"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> myts
<span class="token prompt"> -></span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'mydata-1.dat'</span>
<span class="token prompt"> -></span> <span class="token keyword">USE</span> <span class="token keyword">LOGFILE</span> <span class="token keyword">GROUP</span> mylg
<span class="token prompt"> -></span> <span class="token keyword">ENGINE</span><span class="token operator">=</span><span class="token keyword">NDB</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (2.98 sec)</span></code></pre>
</div>
<p>
You can now create a Disk Data table using a
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statement with the
<code class="literal">
TABLESPACE
</code>
and
<code class="literal">
STORAGE DISK
</code>
options, similar to what is shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78349316"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> mytable <span class="token punctuation">(</span>
<span class="token prompt"> -></span> id <span class="token datatype">INT</span> <span class="token keyword">UNSIGNED</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> lname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> fname <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> dob <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> joined <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
<span class="token prompt"> -></span> <span class="token keyword">INDEX</span><span class="token punctuation">(</span>last_name<span class="token punctuation">,</span> first_name<span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token punctuation">)</span>
<span class="token prompt"> -></span> <span class="token keyword">TABLESPACE</span> myts <span class="token keyword">STORAGE</span> <span class="token keyword">DISK</span>
<span class="token prompt"> -></span> <span class="token keyword">ENGINE</span><span class="token operator">=</span><span class="token keyword">NDB</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (1.41 sec)</span></code></pre>
</div>
<p>
It is important to note that only the
<code class="literal">
dob
</code>
and
<code class="literal">
joined
</code>
columns from
<code class="literal">
mytable
</code>
are actually stored on disk, due to the fact that the
<code class="literal">
id
</code>
,
<code class="literal">
lname
</code>
, and
<code class="literal">
fname
</code>
columns are all indexed.
</p>
<p>
As mentioned previously, when
<code class="literal">
CREATE TABLESPACE
</code>
is used with
<code class="literal">
ENGINE [=] NDB
</code>
, a tablespace and
its associated data file are created on each NDB Cluster data
node. You can verify that the data files were created and obtain
information about them by querying the Information Schema
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
FILES
</code>
</a>
table, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25931024"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> FILE_NAME<span class="token punctuation">,</span> FILE_TYPE<span class="token punctuation">,</span> LOGFILE_GROUP_NAME<span class="token punctuation">,</span> <span class="token keyword">STATUS</span><span class="token punctuation">,</span> EXTRA
<span class="token prompt"> -></span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>FILES
<span class="token prompt"> -></span> <span class="token keyword">WHERE</span> TABLESPACE_NAME <span class="token operator">=</span> <span class="token string">'myts'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> file_name <span class="token punctuation">|</span> file_type <span class="token punctuation">|</span> logfile_group_name <span class="token punctuation">|</span> status <span class="token punctuation">|</span> extra <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> mydata<span class="token punctuation">-</span>1.dat <span class="token punctuation">|</span> DATAFILE <span class="token punctuation">|</span> mylg <span class="token punctuation">|</span> NORMAL <span class="token punctuation">|</span> CLUSTER_NODE=5 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> mydata<span class="token punctuation">-</span>1.dat <span class="token punctuation">|</span> DATAFILE <span class="token punctuation">|</span> mylg <span class="token punctuation">|</span> NORMAL <span class="token punctuation">|</span> CLUSTER_NODE=6 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> TABLESPACE <span class="token punctuation">|</span> mylg <span class="token punctuation">|</span> NORMAL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">3 rows in set (0.01 sec)</span></code></pre>
</div>
<p>
For additional information and examples, see
<a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects">
Section 25.6.11.1, “NDB Cluster Disk Data Objects”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/apis-ruby.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="apis-ruby">
</a>
31.11 MySQL Ruby APIs
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="apis-ruby-mysqlruby.html">
31.11.1 The MySQL/Ruby API
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="apis-ruby-rubymysql.html">
31.11.2 The Ruby/MySQL API
</a>
</span>
</dt>
</dl>
</div>
<a class="indexterm" name="idm46045060297376">
</a>
<p>
The
<code class="literal">
mysql2
</code>
Ruby gem provides an API for
connecting to MySQL, performing queries, and iterating through
results; it is intended to support MySQL 5.7 and MySQL 8.0. For more
information, see the
<a class="ulink" href="https://rubygems.org/gems/mysql2/" target="_blank">
<code class="literal">
mysql2
</code>
page at RubyGems.org
</a>
or the project's
<a class="ulink" href="https://github.com/brianmario/mysql2" target="_blank">
GitHub
page
</a>
.
</p>
<p>
For background and syntax information about the Ruby language, see
<a class="ulink" href="http://www.ruby-lang.org" target="_blank">
Ruby Programming
Language
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sys-schema-tables-with-full-table-scans.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="sys-schema-tables-with-full-table-scans">
</a>
30.4.3.31 The schema_tables_with_full_table_scans and
x$schema_tables_with_full_table_scans Views
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045062286656">
</a>
<a class="indexterm" name="idm46045062285136">
</a>
<a class="indexterm" name="idm46045062283616">
</a>
<a class="indexterm" name="idm46045062282096">
</a>
<p>
These views display which tables are being accessed with full
table scans. By default, rows are sorted by descending rows
scanned.
</p>
<p>
The
<a class="link" href="sys-schema-tables-with-full-table-scans.html" title="30.4.3.31 The schema_tables_with_full_table_scans and x$schema_tables_with_full_table_scans Views">
<code class="literal">
schema_tables_with_full_table_scans
</code>
</a>
and
<a class="link" href="sys-schema-tables-with-full-table-scans.html" title="30.4.3.31 The schema_tables_with_full_table_scans and x$schema_tables_with_full_table_scans Views">
<code class="literal">
x$schema_tables_with_full_table_scans
</code>
</a>
views have these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
object_schema
</code>
</p>
<p>
The schema name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
object_name
</code>
</p>
<p>
The table name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
rows_full_scanned
</code>
</p>
<p>
The total number of rows scanned by full scans of the
table.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
latency
</code>
</p>
<p>
The total wait time of full scans of the table.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/online-ddl-parallel-thread-configuration.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="online-ddl-parallel-thread-configuration">
</a>
17.12.5 Configuring Parallel Threads for Online DDL Operations
</h3>
</div>
</div>
</div>
<p>
The workflow of an online DDL operation that creates or rebuilds a
secondary index involves:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Scanning the clustered index and writing data to temporary
sort files
</p>
</li>
<li class="listitem">
<p>
Sorting the data
</p>
</li>
<li class="listitem">
<p>
Loading sorted data from the temporary sort files into the
secondary index
</p>
</li>
</ul>
</div>
<p>
The number of parallel threads that can be used to scan clustered
index is defined by the
<a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads">
<code class="literal">
innodb_parallel_read_threads
</code>
</a>
variable. The default setting is calculated by the number of
available logical processors on the system divided by 8, with a
minimum default value of 4. The maximum setting is 256, which is
the maximum number for all sessions. The actual number of threads
that scan the clustered index is the number defined by the
<a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads">
<code class="literal">
innodb_parallel_read_threads
</code>
</a>
setting or the number of index subtrees to scan, whichever is
smaller. If the thread limit is reached, sessions fall back to
using a single thread.
</p>
<p>
The number of parallel threads that sort and load data is
controlled by the
<a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads">
<code class="literal">
innodb_ddl_threads
</code>
</a>
variable. The
default setting is 4.
</p>
<p>
The following limitations apply:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Parallel threads are not supported for building indexes that
include virtual columns.
</p>
</li>
<li class="listitem">
<p>
Parallel threads are not supported for full-text index
creation.
</p>
</li>
<li class="listitem">
<p>
Parallel threads are not supported for spatial index creation.
</p>
</li>
<li class="listitem">
<p>
Parallel scan is not supported on tables defined with virtual
columns.
</p>
</li>
<li class="listitem">
<p>
Parallel scan is not supported on tables defined with a
full-text index.
</p>
</li>
<li class="listitem">
<p>
Parallel scan is not supported on tables defined with a
spatial index.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/windows-postinstallation.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="windows-postinstallation">
</a>
2.3.5 Windows Postinstallation Procedures
</h3>
</div>
</div>
</div>
<p>
GUI tools exist that perform most of the tasks described in this
section, including:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="link" href="mysql-configurator.html" title="2.3.2 Configuration: Using MySQL Configurator">
MySQL Configurator
</a>
: Used to
configure the MySQL server.
</p>
</li>
<li class="listitem">
<p>
<a class="link" href="workbench.html" title="Chapter 33 MySQL Workbench">
MySQL Workbench
</a>
: Manages the
MySQL server and edits SQL statements.
</p>
</li>
</ul>
</div>
<p>
If necessary, initialize the data directory and create the MySQL
grant tables. Windows installation operations performed by
MySQL Configurator can initialize the data directory automatically. For
installation from a ZIP Archive package, initialize the data
directory as described at
<a class="xref" href="data-directory-initialization.html" title="2.9.1 Initializing the Data Directory">
Section 2.9.1, “Initializing the Data Directory”
</a>
.
</p>
<p>
Regarding passwords, if you configured MySQL using the MySQL Configurator,
you may have already assigned a password to the initial
<code class="literal">
root
</code>
account. (See
<a class="xref" href="mysql-configurator.html" title="2.3.2 Configuration: Using MySQL Configurator">
Section 2.3.2, “Configuration: Using MySQL Configurator”
</a>
.) Otherwise, use the
password-assignment procedure given in
<a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account">
Section 2.9.4, “Securing the Initial MySQL Account”
</a>
.
</p>
<p>
Before assigning a password, you might want to try running some
client programs to make sure that you can connect to the server
and that it is operating properly. Make sure that the server is
running (see
<a class="xref" href="windows-server-first-start.html" title="2.3.3.5 Starting the Server for the First Time">
Section 2.3.3.5, “Starting the Server for the First Time”
</a>
). You
can also set up a MySQL service that runs automatically when
Windows starts (see
<a class="xref" href="windows-start-service.html" title="2.3.3.8 Starting MySQL as a Windows Service">
Section 2.3.3.8, “Starting MySQL as a Windows Service”
</a>
).
</p>
<p>
These instructions assume that your current location is the MySQL
installation directory and that it has a
<code class="filename">
bin
</code>
subdirectory containing the MySQL programs used here. If that is
not true, adjust the command path names accordingly.
</p>
<p>
If you installed MySQL using the MSI, the default installation
directory is
<code class="filename">
C:\Program Files\MySQL\MySQL Server
8.4
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa87946135"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> cd</span> <span class="token atrule">"C:\Program Files\MySQL\MySQL Server 8.4"</span></code></pre>
</div>
<p>
A common installation location for installation from a ZIP archive
is
<code class="filename">
C:\mysql
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa1288214"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> cd</span> C<span class="token punctuation">:</span>\mysql</code></pre>
</div>
<a class="indexterm" name="idm46045331792912">
</a>
<a class="indexterm" name="idm46045331791824">
</a>
<p>
Alternatively, add the
<code class="filename">
bin
</code>
directory to your
<code class="literal">
PATH
</code>
environment variable setting. That enables
your command interpreter to find MySQL programs properly, so that
you can run a program by typing only its name, not its path name.
See
<a class="xref" href="mysql-installation-windows-path.html" title="2.3.3.7 Customizing the PATH for MySQL Tools">
Section 2.3.3.7, “Customizing the PATH for MySQL Tools”
</a>
.
</p>
<p>
With the server running, issue the following commands to verify
that you can retrieve information from the server. The output
should be similar to that shown here.
</p>
<p>
Use
<a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information">
<span class="command">
<strong>
mysqlshow
</strong>
</span>
</a>
to see what databases exist:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa81598177"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> bin\mysqlshow</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Databases <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> information_schema <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> mysql <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> performance_schema <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> sys <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
The list of installed databases may vary, but always includes at
least
<code class="literal">
mysql
</code>
and
<code class="literal">
information_schema
</code>
.
</p>
<p>
The preceding command (and commands for other MySQL programs such
as
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
) may not work if the correct MySQL
account does not exist. For example, the program may fail with an
error, or you may not be able to view all databases. If you
configured MySQL using MySQL Configurator, the
<code class="literal">
root
</code>
user
is created automatically with the password you supplied. In this
case, you should use the
<code class="option">
-u root
</code>
and
<code class="option">
-p
</code>
options. (You must use those options if you
have already secured the initial MySQL accounts.) With
<code class="option">
-p
</code>
, the client program prompts for the
<code class="literal">
root
</code>
password. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa99969795"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> bin\mysqlshow</span> <span class="token property">-u</span> root <span class="token property">-p</span>
Enter password<span class="token punctuation">:</span> <span class="token punctuation"></span><em class="replaceable"><span class="token punctuation">(</span>enter root password here<span class="token punctuation">)</span></em><span class="token punctuation"></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Databases <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> information_schema <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> mysql <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> performance_schema <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> sys <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
If you specify a database name,
<a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information">
<span class="command">
<strong>
mysqlshow
</strong>
</span>
</a>
displays a list of the tables within the database:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa31357807"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> bin\mysqlshow</span> mysql
Database<span class="token punctuation">:</span> mysql
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Tables <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> columns_priv <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> component <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> db <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> default_roles <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> engine_cost <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> func <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> general_log <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> global_grants <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> gtid_executed <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> help_category <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> help_keyword <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> help_relation <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> help_topic <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> innodb_index_stats <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> innodb_table_stats <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> ndb_binlog_index <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> password_history <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> plugin <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> procs_priv <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> proxies_priv <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> role_edges <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> server_cost <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> servers <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> slave_master_info <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> slave_relay_log_info <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> slave_worker_info <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> slow_log <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> tables_priv <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> time_zone <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> time_zone_leap_second <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> time_zone_name <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> time_zone_transition <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> time_zone_transition_type <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> user <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
Use the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
program to select information
from a table in the
<code class="literal">
mysql
</code>
database:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa91697589"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> bin\mysql</span> <span class="token property">-e</span> <span class="token atrule">"SELECT User, Host, plugin FROM mysql.user"</span> mysql
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> User <span class="token punctuation">|</span> Host <span class="token punctuation">|</span> plugin <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> root <span class="token punctuation">|</span> localhost <span class="token punctuation">|</span> caching_sha2_password <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
For more information about
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
and
<a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information">
<span class="command">
<strong>
mysqlshow
</strong>
</span>
</a>
, see
<a class="xref" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
Section 6.5.1, “mysql — The MySQL Command-Line Client”
</a>
, and
<a class="xref" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information">
Section 6.5.6, “mysqlshow — Display Database, Table, and Column Information”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/forcing-innodb-recovery.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="forcing-innodb-recovery">
</a>
17.20.3 Forcing InnoDB Recovery
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045148999312">
</a>
<a class="indexterm" name="idm46045148997408">
</a>
<a class="indexterm" name="idm46045148995952">
</a>
<p>
To investigate database page corruption, you might dump your
tables from the database with
<a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement">
<code class="literal">
SELECT ... INTO
OUTFILE
</code>
</a>
. Usually, most of the data obtained in this way
is intact. Serious corruption might cause
<code class="literal">
SELECT * FROM
<em class="replaceable">
<code>
tbl_name
</code>
</em>
</code>
statements or
<code class="literal">
InnoDB
</code>
background operations to unexpectedly
exit or assert, or even cause
<code class="literal">
InnoDB
</code>
roll-forward recovery to crash. In such cases, you can use the
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
option to
force the
<code class="literal">
InnoDB
</code>
storage engine to start up
while preventing background operations from running, so that you
can dump your tables. For example, you can add the following line
to the
<code class="literal">
[mysqld]
</code>
section of your option file
before restarting the server:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa47000348"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span>
<span class="token constant">innodb_force_recovery</span> <span class="token attr-value"><span class="token punctuation">=</span> 1</span></code></pre>
</div>
<p>
For information about using option files, see
<a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files">
Section 6.2.2.2, “Using Option Files”
</a>
.
</p>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
Only set
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
to a value greater than 0 in an emergency situation, so that you
can start
<code class="literal">
InnoDB
</code>
and dump your tables. Before
doing so, ensure that you have a backup copy of your database in
case you need to recreate it. Values of 4 or greater can
permanently corrupt data files. Only use an
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
setting
of 4 or greater on a production server instance after you have
successfully tested the setting on a separate physical copy of
your database. When forcing
<code class="literal">
InnoDB
</code>
recovery,
you should always start with
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery=1
</code>
</a>
and
only increase the value incrementally, as necessary.
</p>
</div>
<p>
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
is 0 by
default (normal startup without forced recovery). The permissible
nonzero values for
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
are 1 to 6.
A larger value includes the functionality of lesser values. For
example, a value of 3 includes all of the functionality of values
1 and 2.
</p>
<p>
If you are able to dump your tables with an
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
value of 3
or less, then you are relatively safe that only some data on
corrupt individual pages is lost. A value of 4 or greater is
considered dangerous because data files can be permanently
corrupted. A value of 6 is considered drastic because database
pages are left in an obsolete state, which in turn may introduce
more corruption into
<a class="link" href="glossary.html#glos_b_tree" title="B-tree">
B-trees
</a>
and other database structures.
</p>
<p>
As a safety measure,
<code class="literal">
InnoDB
</code>
prevents
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
, or
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
operations when
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
is greater
than 0. An
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
setting of 4 or greater places
<code class="literal">
InnoDB
</code>
in
read-only mode.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
1
</code>
(
<code class="literal">
SRV_FORCE_IGNORE_CORRUPT
</code>
)
</p>
<p>
Lets the server run even if it detects a corrupt
<a class="link" href="glossary.html#glos_page" title="page">
page
</a>
. Tries to make
<code class="literal">
SELECT * FROM
<em class="replaceable">
<code>
tbl_name
</code>
</em>
</code>
jump over
corrupt index records and pages, which helps in dumping
tables.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
2
</code>
(
<code class="literal">
SRV_FORCE_NO_BACKGROUND
</code>
)
</p>
<p>
Prevents the
<a class="link" href="glossary.html#glos_master_thread" title="master thread">
master
thread
</a>
and any
<a class="link" href="glossary.html#glos_purge_thread" title="purge thread">
purge
threads
</a>
from running. If an unexpected exit would occur
during the
<a class="link" href="glossary.html#glos_purge" title="purge">
purge
</a>
operation,
this recovery value prevents it.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
3
</code>
(
<code class="literal">
SRV_FORCE_NO_TRX_UNDO
</code>
)
</p>
<p>
Does not run transaction
<a class="link" href="glossary.html#glos_rollback" title="rollback">
rollbacks
</a>
after
<a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery">
crash recovery
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
4
</code>
(
<code class="literal">
SRV_FORCE_NO_IBUF_MERGE
</code>
)
</p>
<p>
Prevents
<a class="link" href="glossary.html#glos_insert_buffer" title="insert buffer">
insert
buffer
</a>
merge operations. If they would cause a crash,
does not do them. Does not calculate table
<a class="link" href="glossary.html#glos_statistics" title="statistics">
statistics
</a>
. This value
can permanently corrupt data files. After using this value, be
prepared to drop and recreate all secondary indexes. Sets
<code class="literal">
InnoDB
</code>
to read-only.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
5
</code>
(
<code class="literal">
SRV_FORCE_NO_UNDO_LOG_SCAN
</code>
)
</p>
<p>
Does not look at
<a class="link" href="glossary.html#glos_undo_log" title="undo log">
undo
logs
</a>
when starting the database:
<code class="literal">
InnoDB
</code>
treats even incomplete transactions
as committed. This value can permanently corrupt data files.
Sets
<code class="literal">
InnoDB
</code>
to read-only.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
6
</code>
(
<code class="literal">
SRV_FORCE_NO_LOG_REDO
</code>
)
</p>
<p>
Does not do the
<a class="link" href="glossary.html#glos_redo_log" title="redo log">
redo log
</a>
roll-forward in connection with recovery. This value can
permanently corrupt data files. Leaves database pages in an
obsolete state, which in turn may introduce more corruption
into B-trees and other database structures. Sets
<code class="literal">
InnoDB
</code>
to read-only.
</p>
</li>
</ul>
</div>
<p>
You can
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
from tables to dump
them. With an
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
value of 3
or less you can
<code class="literal">
DROP
</code>
or
<code class="literal">
CREATE
</code>
tables.
<a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
<code class="literal">
DROP
TABLE
</code>
</a>
is also supported with an
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
value
greater than 3.
<a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
<code class="literal">
DROP TABLE
</code>
</a>
is not
permitted with an
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
value
greater than 4.
</p>
<p>
If you know that a given table is causing an unexpected exit on
rollback, you can drop it. If you encounter a runaway rollback
caused by a failing mass import or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER
TABLE
</code>
</a>
, you can kill the
<a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
<span class="command">
<strong>
mysqld
</strong>
</span>
</a>
process and set
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
to
<code class="literal">
3
</code>
to bring the database up without the
rollback, and then
<code class="literal">
DROP
</code>
the table that is
causing the runaway rollback.
</p>
<p>
If corruption within the table data prevents you from dumping the
entire table contents, a query with an
<code class="literal">
ORDER BY
<em class="replaceable">
<code>
primary_key
</code>
</em>
DESC
</code>
clause might
be able to dump the portion of the table after the corrupted part.
</p>
<p>
If a high
<a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery">
<code class="literal">
innodb_force_recovery
</code>
</a>
value is required to start
<code class="literal">
InnoDB
</code>
, there may be
corrupted data structures that could cause complex queries
(queries containing
<code class="literal">
WHERE
</code>
,
<code class="literal">
ORDER
BY
</code>
, or other clauses) to fail. In this case, you may
only be able to run basic
<code class="literal">
SELECT * FROM t
</code>
queries.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/dynindex-operator.html | <div id="docs-body">
<div class="index">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="dynindex-operator">
</a>
Operator Index
</h2>
</div>
</div>
</div>
<p>
<a name="op-index-top">
</a>
<a class="link" href="dynindex-operator.html#op-index-Symbols" title="Symbols">
Symbols
</a>
|
<a class="link" href="dynindex-operator.html#op-index-A" title="A">
A
</a>
|
<a class="link" href="dynindex-operator.html#op-index-B" title="B">
B
</a>
|
<a class="link" href="dynindex-operator.html#op-index-C" title="C">
C
</a>
|
<a class="link" href="dynindex-operator.html#op-index-D" title="D">
D
</a>
|
<a class="link" href="dynindex-operator.html#op-index-E" title="E">
E
</a>
|
<a class="link" href="dynindex-operator.html#op-index-I" title="I">
I
</a>
|
<a class="link" href="dynindex-operator.html#op-index-L" title="L">
L
</a>
|
<a class="link" href="dynindex-operator.html#op-index-M" title="M">
M
</a>
|
<a class="link" href="dynindex-operator.html#op-index-N" title="N">
N
</a>
|
<a class="link" href="dynindex-operator.html#op-index-O" title="O">
O
</a>
|
<a class="link" href="dynindex-operator.html#op-index-R" title="R">
R
</a>
|
<a class="link" href="dynindex-operator.html#op-index-V" title="V">
V
</a>
|
<a class="link" href="dynindex-operator.html#op-index-X" title="X">
X
</a>
</p>
<div class="indexdiv">
<a name="op-index-Symbols">
</a>
<h3 class="title">
Symbols
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
-
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="cast-functions.html" title="14.10 Cast Functions and Operators">
Section 14.10, “Cast Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="numeric-type-syntax.html" title="13.1.1 Numeric Data Type Syntax">
Section 13.1.1, “Numeric Data Type Syntax”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
!
</h3>
<dl>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
!=
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
%
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
&
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
Section 15.1.20, “CREATE TABLE Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
&&
</h3>
<dl>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
>
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
->
</h3>
<dl>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="create-table-secondary-indexes.html" title="15.1.20.9 Secondary Indexes and Generated Columns">
Section 15.1.20.9, “Secondary Indexes and Generated Columns”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
>>
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
->>
</h3>
<dl>
<dt>
<a class="xref" href="create-index.html" title="15.1.15 CREATE INDEX Statement">
Section 15.1.15, “CREATE INDEX Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="create-table-secondary-indexes.html" title="15.1.20.9 Secondary Indexes and Generated Columns">
Section 15.1.20.9, “Secondary Indexes and Generated Columns”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
>=
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
<
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="working-with-null.html" title="5.3.4.6 Working with NULL Values">
Section 5.3.4.6, “Working with NULL Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
<>
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="working-with-null.html" title="5.3.4.6 Working with NULL Values">
Section 5.3.4.6, “Working with NULL Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
<<
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
<=
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
<=>
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="correlated-subqueries.html" title="15.2.15.7 Correlated Subqueries">
Section 15.2.15.7, “Correlated Subqueries”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="tracing-example.html" title="10.15.12 Example">
Section 10.15.12, “Example”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="type-conversion.html" title="14.3 Type Conversion in Expression Evaluation">
Section 14.3, “Type Conversion in Expression Evaluation”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
*
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="numeric-type-syntax.html" title="13.1.1 Numeric Data Type Syntax">
Section 13.1.1, “Numeric Data Type Syntax”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
+
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="cast-functions.html" title="14.10 Cast Functions and Operators">
Section 14.10, “Cast Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="numeric-type-syntax.html" title="13.1.1 Numeric Data Type Syntax">
Section 13.1.1, “Numeric Data Type Syntax”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
/
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
:=
</h3>
<dl>
<dt>
<a class="xref" href="assignment-operators.html" title="14.4.4 Assignment Operators">
Section 14.4.4, “Assignment Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment">
Section 15.7.6.1, “SET Syntax for Variable Assignment”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="user-variables.html" title="11.4 User-Defined Variables">
Section 11.4, “User-Defined Variables”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
=
</h3>
<dl>
<dt>
<a class="xref" href="assignment-operators.html" title="14.4.4 Assignment Operators">
Section 14.4.4, “Assignment Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="correlated-subqueries.html" title="15.2.15.7 Correlated Subqueries">
Section 15.2.15.7, “Correlated Subqueries”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="subquery-restrictions.html" title="15.2.15.12 Restrictions on Subqueries">
Section 15.2.15.12, “Restrictions on Subqueries”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment">
Section 15.7.6.1, “SET Syntax for Variable Assignment”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="user-variables.html" title="11.4 User-Defined Variables">
Section 11.4, “User-Defined Variables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="working-with-null.html" title="5.3.4.6 Working with NULL Values">
Section 5.3.4.6, “Working with NULL Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
^
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
|
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
||
</h3>
<dl>
<dt>
<a class="xref" href="string-functions-charset.html" title="14.8.3 Character Set and Collation of Function Results">
Section 14.8.3, “Character Set and Collation of Function Results”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="charset-collate-precedence.html" title="12.8.2 COLLATE Clause Precedence">
Section 12.8.2, “COLLATE Clause Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sql-mode.html" title="7.1.11 Server SQL Modes">
Section 7.1.11, “Server SQL Modes”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
~
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-A">
</a>
<h3 class="title">
A
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
AND
</h3>
<dl>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
Section 15.1.20, “CREATE TABLE Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-merge-optimization.html" title="10.2.1.3 Index Merge Optimization">
Section 10.2.1.3, “Index Merge Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="subquery-optimization-with-exists.html" title="10.2.2.3 Optimizing Subqueries with the EXISTS Strategy">
Section 10.2.2.3, “Optimizing Subqueries with the EXISTS Strategy”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="subquery-restrictions.html" title="15.2.15.12 Restrictions on Subqueries">
Section 15.2.15.12, “Restrictions on Subqueries”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="row-constructor-optimization.html" title="10.2.1.22 Row Constructor Expression Optimization">
Section 10.2.1.22, “Row Constructor Expression Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="searching-on-two-keys.html" title="5.6.7 Searching on Two Keys">
Section 5.6.7, “Searching on Two Keys”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-shell-tutorial-javascript-table-select.html" title="22.3.4.2 Select Tables">
Section 22.3.4.2, “Select Tables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-shell-tutorial-python-table-select.html" title="22.4.4.2 Select Tables">
Section 22.4.4.2, “Select Tables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="selecting-rows.html" title="5.3.4.2 Selecting Particular Rows">
Section 5.3.4.2, “Selecting Particular Rows”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="view-algorithms.html" title="27.5.2 View Processing Algorithms">
Section 27.5.2, “View Processing Algorithms”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-B">
</a>
<h3 class="title">
B
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
BETWEEN
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="condition-filtering.html" title="10.2.1.13 Condition Filtering">
Section 10.2.1.13, “Condition Filtering”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="prepare.html" title="15.5.1 PREPARE Statement">
Section 15.5.1, “PREPARE Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="type-conversion.html" title="14.3 Type Conversion in Expression Evaluation">
Section 14.3, “Type Conversion in Expression Evaluation”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
BINARY
</h3>
<dl>
<dt>
<a class="xref" href="bit-functions.html" title="14.12 Bit Functions and Operators">
Section 14.12, “Bit Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="cast-functions.html" title="14.10 Cast Functions and Operators">
Section 14.10, “Cast Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="optimize-character.html" title="10.4.2.2 Optimizing for Character and String Types">
Section 10.4.2.2, “Optimizing for Character and String Types”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="pattern-matching.html" title="5.3.4.7 Pattern Matching">
Section 5.3.4.7, “Pattern Matching”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sorting-rows.html" title="5.3.4.4 Sorting Rows">
Section 5.3.4.4, “Sorting Rows”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-C">
</a>
<h3 class="title">
C
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
CASE
</h3>
<dl>
<dt>
<a class="xref" href="case.html" title="15.6.5.1 CASE Statement">
Section 15.6.5.1, “CASE Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="flow-control-functions.html" title="14.5 Flow Control Functions">
Section 14.5, “Flow Control Functions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="prepare.html" title="15.5.1 PREPARE Statement">
Section 15.5.1, “PREPARE Statement”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
CASE value WHEN compare_value THEN result END
</h3>
<dl>
<dt>
<a class="xref" href="flow-control-functions.html" title="14.5 Flow Control Functions">
Section 14.5, “Flow Control Functions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
CASE WHEN condition THEN result END
</h3>
<dl>
<dt>
<a class="xref" href="flow-control-functions.html" title="14.5 Flow Control Functions">
Section 14.5, “Flow Control Functions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
CASE WHEN expr1 = expr2 THEN NULL ELSE expr1 END
</h3>
<dl>
<dt>
<a class="xref" href="flow-control-functions.html" title="14.5 Flow Control Functions">
Section 14.5, “Flow Control Functions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
column->>path
</h3>
<dl>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
column->path
</h3>
<dl>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-D">
</a>
<h3 class="title">
D
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
DIV
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="partitioning-limitations.html" title="26.6 Restrictions and Limitations on Partitioning">
Section 26.6, “Restrictions and Limitations on Partitioning”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-E">
</a>
<h3 class="title">
E
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
EXISTS
</h3>
<dl>
<dt>
<a class="xref" href="semijoins-antijoins.html" title="10.2.2.1 Optimizing IN and EXISTS Subquery Predicates with Semijoin and Antijoin Transformations">
Section 10.2.2.1, “Optimizing IN and EXISTS Subquery Predicates with Semijoin and Antijoin
Transformations”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
EXISTS()
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr BETWEEN min AND max
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr IN ()
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr LIKE pat
</h3>
<dl>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr NOT BETWEEN min AND max
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr NOT IN ()
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr NOT LIKE pat
</h3>
<dl>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr NOT REGEXP pat
</h3>
<dl>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr NOT RLIKE pat
</h3>
<dl>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr REGEXP pat
</h3>
<dl>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr RLIKE pat
</h3>
<dl>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
expr1 SOUNDS LIKE expr2
</h3>
<dl>
<dt>
<a class="xref" href="string-functions.html" title="14.8 String Functions and Operators">
Section 14.8, “String Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-I">
</a>
<h3 class="title">
I
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IN
</h3>
<dl>
<dt>
<a class="xref" href="semijoins-antijoins.html" title="10.2.2.1 Optimizing IN and EXISTS Subquery Predicates with Semijoin and Antijoin Transformations">
Section 10.2.2.1, “Optimizing IN and EXISTS Subquery Predicates with Semijoin and Antijoin
Transformations”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IN()
</h3>
<dl>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="generated-column-index-optimizations.html" title="10.3.11 Optimizer Use of Generated Column Indexes">
Section 10.3.11, “Optimizer Use of Generated Column Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="row-constructor-optimization.html" title="10.2.1.22 Row Constructor Expression Optimization">
Section 10.2.1.22, “Row Constructor Expression Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json.html" title="13.5 The JSON Data Type">
Section 13.5, “The JSON Data Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="type-conversion.html" title="14.3 Type Conversion in Expression Evaluation">
Section 14.3, “Type Conversion in Expression Evaluation”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-cluster-what-is-new.html" title="25.2.4 What is New in MySQL NDB Cluster 8.4">
Section 25.2.4, “What is New in MySQL NDB Cluster 8.4”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IS
</h3>
<dl>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IS boolean_value
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IS NOT boolean_value
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IS NOT NULL
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="problems-with-null.html" title="B.3.4.3 Problems with NULL Values">
Section B.3.4.3, “Problems with NULL Values”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="working-with-null.html" title="5.3.4.6 Working with NULL Values">
Section 5.3.4.6, “Working with NULL Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
IS NULL
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="is-null-optimization.html" title="10.2.1.15 IS NULL Optimization">
Section 10.2.1.15, “IS NULL Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="subquery-optimization-with-exists.html" title="10.2.2.3 Optimizing Subqueries with the EXISTS Strategy">
Section 10.2.2.3, “Optimizing Subqueries with the EXISTS Strategy”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="problems-with-null.html" title="B.3.4.3 Problems with NULL Values">
Section B.3.4.3, “Problems with NULL Values”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables">
Section 7.1.8, “Server System Variables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="working-with-null.html" title="5.3.4.6 Working with NULL Values">
Section 5.3.4.6, “Working with NULL Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-L">
</a>
<h3 class="title">
L
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
LIKE
</h3>
<dl>
<dt>
<a class="xref" href="request-access.html" title="8.2.7 Access Control, Stage 2: Request Verification">
Section 8.2.7, “Access Control, Stage 2: Request Verification”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="cast-functions.html" title="14.10 Cast Functions and Operators">
Section 14.10, “Cast Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="charset-mysql.html" title="12.2 Character Sets and Collations in MySQL">
Section 12.2, “Character Sets and Collations in MySQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-btree-hash.html" title="10.3.9 Comparison of B-Tree and Hash Indexes">
Section 10.3.9, “Comparison of B-Tree and Hash Indexes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="explain-output.html" title="10.8.2 EXPLAIN Output Format">
Section 10.8.2, “EXPLAIN Output Format”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements">
Section 28.8, “Extensions to SHOW Statements”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="help.html" title="15.8.3 HELP Statement">
Section 15.8.3, “HELP Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="faqs-cjk.html" title="A.11 MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets">
Section A.11, “MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean
Character Sets”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-server-side-help.html" title="6.5.1.4 mysql Client Server-Side Help">
Section 6.5.1.4, “mysql Client Server-Side Help”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-cluster-replication-schema.html" title="25.7.4 NDB Cluster Replication Schema and Tables">
Section 25.7.4, “NDB Cluster Replication Schema and Tables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="pattern-matching.html" title="5.3.4.7 Pattern Matching">
Section 5.3.4.7, “Pattern Matching”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="performance-schema-instrument-filtering.html" title="29.4.4 Pre-Filtering by Instrument">
Section 29.4.4, “Pre-Filtering by Instrument”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-cluster-sql-statements.html" title="25.6.20 Quick Reference: NDB Cluster SQL Statements">
Section 25.6.20, “Quick Reference: NDB Cluster SQL Statements”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="replication-options-replica.html" title="19.1.6.3 Replica Server Options and Variables">
Section 19.1.6.3, “Replica Server Options and Variables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="replication-rules-channel-based-filters.html" title="19.2.5.4 Replication Channel Based Filters">
Section 19.2.5.4, “Replication Channel Based Filters”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sql-mode.html" title="7.1.11 Server SQL Modes">
Section 7.1.11, “Server SQL Modes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement">
Section 15.7.7.4, “SHOW CHARACTER SET Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-collation.html" title="15.7.7.5 SHOW COLLATION Statement">
Section 15.7.7.5, “SHOW COLLATION Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement">
Section 15.7.7.6, “SHOW COLUMNS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement">
Section 15.7.7.15, “SHOW DATABASES Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-events.html" title="15.7.7.19 SHOW EVENTS Statement">
Section 15.7.7.19, “SHOW EVENTS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-open-tables.html" title="15.7.7.25 SHOW OPEN TABLES Statement">
Section 15.7.7.25, “SHOW OPEN TABLES Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement">
Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-status.html" title="15.7.7.37 SHOW STATUS Statement">
Section 15.7.7.37, “SHOW STATUS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement">
Section 15.7.7.38, “SHOW TABLE STATUS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement">
Section 15.7.7.39, “SHOW TABLES Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-triggers.html" title="15.7.7.40 SHOW TRIGGERS Statement">
Section 15.7.7.40, “SHOW TRIGGERS Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show-variables.html" title="15.7.7.41 SHOW VARIABLES Statement">
Section 15.7.7.41, “SHOW VARIABLES Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="account-names.html" title="8.2.4 Specifying Account Names">
Section 8.2.4, “Specifying Account Names”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-literals.html" title="11.1.1 String Literals">
Section 11.1.1, “String Literals”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="structured-system-variables.html" title="7.1.9.5 Structured System Variables">
Section 7.1.9.5, “Structured System Variables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="charset-binary-collations.html" title="12.8.5 The binary Collation Compared to _bin Collations">
Section 12.8.5, “The binary Collation Compared to _bin Collations”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sys-ps-setup-disable-consumer.html" title="30.4.4.5 The ps_setup_disable_consumer() Procedure">
Section 30.4.4.5, “The ps_setup_disable_consumer() Procedure”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sys-ps-setup-disable-instrument.html" title="30.4.4.6 The ps_setup_disable_instrument() Procedure">
Section 30.4.4.6, “The ps_setup_disable_instrument() Procedure”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sys-ps-setup-enable-consumer.html" title="30.4.4.9 The ps_setup_enable_consumer() Procedure">
Section 30.4.4.9, “The ps_setup_enable_consumer() Procedure”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sys-ps-setup-enable-instrument.html" title="30.4.4.10 The ps_setup_enable_instrument() Procedure">
Section 30.4.4.10, “The ps_setup_enable_instrument() Procedure”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="set.html" title="13.3.6 The SET Type">
Section 13.3.6, “The SET Type”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="using-system-variables.html" title="7.1.9 Using System Variables">
Section 7.1.9, “Using System Variables”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
LIKE '_A%'
</h3>
<dl>
<dt>
<a class="xref" href="faqs-cjk.html" title="A.11 MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets">
Section A.11, “MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean
Character Sets”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
LIKE 'pattern'
</h3>
<dl>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="show.html" title="15.7.7 SHOW Statements">
Section 15.7.7, “SHOW Statements”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-M">
</a>
<h3 class="title">
M
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
MEMBER OF()
</h3>
<dl>
<dt>
<a class="xref" href="create-index.html" title="15.1.15 CREATE INDEX Statement">
Section 15.1.15, “CREATE INDEX Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-N">
</a>
<h3 class="title">
N
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
N % M
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mathematical-functions.html" title="14.6.2 Mathematical Functions">
Section 14.6.2, “Mathematical Functions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
N MOD M
</h3>
<dl>
<dt>
<a class="xref" href="arithmetic-functions.html" title="14.6.1 Arithmetic Operators">
Section 14.6.1, “Arithmetic Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mathematical-functions.html" title="14.6.2 Mathematical Functions">
Section 14.6.2, “Mathematical Functions”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT
</h3>
<dl>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sql-mode.html" title="7.1.11 Server SQL Modes">
Section 7.1.11, “Server SQL Modes”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT EXISTS()
</h3>
<dl>
<dt>
<a class="xref" href="comparison-operators.html" title="14.4.2 Comparison Functions and Operators">
Section 14.4.2, “Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT IN()
</h3>
<dl>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT LIKE
</h3>
<dl>
<dt>
<a class="xref" href="pattern-matching.html" title="5.3.4.7 Pattern Matching">
Section 5.3.4.7, “Pattern Matching”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT REGEXP
</h3>
<dl>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
NOT RLIKE
</h3>
<dl>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-O">
</a>
<h3 class="title">
O
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
OR
</h3>
<dl>
<dt>
<a class="xref" href="expressions.html" title="11.5 Expressions">
Section 11.5, “Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="grant.html" title="15.7.1.6 GRANT Statement">
Section 15.7.1.6, “GRANT Statement”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="index-merge-optimization.html" title="10.2.1.3 Index Merge Optimization">
Section 10.2.1.3, “Index Merge Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="subquery-optimization-with-exists.html" title="10.2.2.3 Optimizing Subqueries with the EXISTS Strategy">
Section 10.2.2.3, “Optimizing Subqueries with the EXISTS Strategy”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization">
Section 10.2.1.2, “Range Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="row-constructor-optimization.html" title="10.2.1.22 Row Constructor Expression Optimization">
Section 10.2.1.22, “Row Constructor Expression Optimization”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="searching-on-two-keys.html" title="5.6.7 Searching on Two Keys">
Section 5.6.7, “Searching on Two Keys”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-shell-tutorial-javascript-table-select.html" title="22.3.4.2 Select Tables">
Section 22.3.4.2, “Select Tables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="mysql-shell-tutorial-python-table-select.html" title="22.4.4.2 Select Tables">
Section 22.4.4.2, “Select Tables”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="selecting-rows.html" title="5.3.4.2 Selecting Particular Rows">
Section 5.3.4.2, “Selecting Particular Rows”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="sql-mode.html" title="7.1.11 Server SQL Modes">
Section 7.1.11, “Server SQL Modes”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="string-comparison-functions.html" title="14.8.1 String Comparison Functions and Operators">
Section 14.8.1, “String Comparison Functions and Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-R">
</a>
<h3 class="title">
R
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
REGEXP
</h3>
<dl>
<dt>
<a class="xref" href="extensions-to-ansi.html" title="1.7.1 MySQL Extensions to Standard SQL">
Section 1.7.1, “MySQL Extensions to Standard SQL”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="operator-precedence.html" title="14.4.1 Operator Precedence">
Section 14.4.1, “Operator Precedence”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="pattern-matching.html" title="5.3.4.7 Pattern Matching">
Section 5.3.4.7, “Pattern Matching”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="charset-restrictions.html" title="12.11 Restrictions on Character Sets">
Section 12.11, “Restrictions on Character Sets”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
RLIKE
</h3>
<dl>
<dt>
<a class="xref" href="pattern-matching.html" title="5.3.4.7 Pattern Matching">
Section 5.3.4.7, “Pattern Matching”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="regexp.html" title="14.8.2 Regular Expressions">
Section 14.8.2, “Regular Expressions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="charset-restrictions.html" title="12.11 Restrictions on Character Sets">
Section 12.11, “Restrictions on Character Sets”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-V">
</a>
<h3 class="title">
V
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
value MEMBER OF()
</h3>
<dl>
<dt>
<a class="xref" href="json-search-functions.html" title="14.17.3 Functions That Search JSON Values">
Section 14.17.3, “Functions That Search JSON Values”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<a name="op-index-X">
</a>
<h3 class="title">
X
</h3>
<p>
[
<a class="link" href="dynindex-operator.html#op-index-top">
index top
</a>
]
</p>
<dl>
<dt>
</dt>
<dd>
</dd>
</dl>
</div>
<div class="indexdiv">
<h3 class="title">
XOR
</h3>
<dl>
<dt>
<a class="xref" href="aggregate-functions.html" title="14.19.1 Aggregate Function Descriptions">
Section 14.19.1, “Aggregate Function Descriptions”
</a>
</dt>
<dd>
</dd>
<dt>
<a class="xref" href="logical-operators.html" title="14.4.3 Logical Operators">
Section 14.4.3, “Logical Operators”
</a>
</dt>
<dd>
</dd>
</dl>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/constraint-primary-key.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="constraint-primary-key">
</a>
1.7.3.1 PRIMARY KEY and UNIQUE Index Constraints
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045333149440">
</a>
<a class="indexterm" name="idm46045333147984">
</a>
<a class="indexterm" name="idm46045333146496">
</a>
<p>
Normally, errors occur for data-change statements (such as
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
or
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
) that would violate
primary-key, unique-key, or foreign-key constraints. If you
are using a transactional storage engine such as
<code class="literal">
InnoDB
</code>
, MySQL automatically rolls back the
statement. If you are using a nontransactional storage engine,
MySQL stops processing the statement at the row for which the
error occurred and leaves any remaining rows unprocessed.
</p>
<p>
MySQL supports an
<code class="literal">
IGNORE
</code>
keyword for
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
, and so forth. If you
use it, MySQL ignores primary-key or unique-key violations and
continues processing with the next row. See the section for
the statement that you are using (
<a class="xref" href="insert.html" title="15.2.7 INSERT Statement">
Section 15.2.7, “INSERT Statement”
</a>
,
<a class="xref" href="update.html" title="15.2.17 UPDATE Statement">
Section 15.2.17, “UPDATE Statement”
</a>
, and so forth).
</p>
<p>
You can get information about the number of rows actually
inserted or updated with the
<a class="ulink" href="/doc/c-api/8.4/en/mysql-info.html" target="_top">
<code class="literal">
mysql_info()
</code>
</a>
C API function.
You can also use the
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW
WARNINGS
</code>
</a>
statement. See
<a class="ulink" href="/doc/c-api/8.4/en/mysql-info.html" target="_top">
mysql_info()
</a>
, and
<a class="xref" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
Section 15.7.7.42, “SHOW WARNINGS Statement”
</a>
.
</p>
<p>
<code class="literal">
InnoDB
</code>
and
<code class="literal">
NDB
</code>
tables
support foreign keys. See
<a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints">
Section 1.7.3.2, “FOREIGN KEY Constraints”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-threadstat.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-ndbinfo-threadstat">
</a>
25.6.17.64 The ndbinfo threadstat Table
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045087533696">
</a>
<p>
The
<code class="literal">
threadstat
</code>
table provides a rough
snapshot of statistics for threads running in the
<code class="literal">
NDB
</code>
kernel.
</p>
<p>
The
<code class="literal">
threadstat
</code>
table contains the following
columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
node_id
</code>
</p>
<p>
Node ID
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
thr_no
</code>
</p>
<p>
Thread ID
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
thr_nm
</code>
</p>
<p>
Thread name
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_loop
</code>
</p>
<p>
Number of loops in main loop
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_exec
</code>
</p>
<p>
Number of signals executed
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_wait
</code>
</p>
<p>
Number of times waiting for additional input
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_l_sent_prioa
</code>
</p>
<p>
Number of priority A signals sent to own node
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_l_sent_priob
</code>
</p>
<p>
Number of priority B signals sent to own node
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_r_sent_prioa
</code>
</p>
<p>
Number of priority A signals sent to remote node
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
c_r_sent_priob
</code>
</p>
<p>
Number of priority B signals sent to remote node
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_tid
</code>
</p>
<p>
OS thread ID
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_now
</code>
</p>
<p>
OS time (ms)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_utime
</code>
</p>
<p>
OS user CPU time (µs)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_stime
</code>
</p>
<p>
OS system CPU time (µs)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_minflt
</code>
</p>
<p>
OS page reclaims (soft page faults)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_majflt
</code>
</p>
<p>
OS page faults (hard page faults)
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_nvcsw
</code>
</p>
<p>
OS voluntary context switches
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
os_ru_nivcsw
</code>
</p>
<p>
OS involuntary context switches
</p>
</li>
</ul>
</div>
<h5>
<a name="idm46045087494320">
</a>
Notes
</h5>
<p>
<code class="literal">
os_time
</code>
uses the system
<code class="function">
gettimeofday()
</code>
call.
</p>
<p>
The values of the
<code class="literal">
os_ru_utime
</code>
,
<code class="literal">
os_ru_stime
</code>
,
<code class="literal">
os_ru_minflt
</code>
,
<code class="literal">
os_ru_majflt
</code>
,
<code class="literal">
os_ru_nvcsw
</code>
,
and
<code class="literal">
os_ru_nivcsw
</code>
columns are obtained using
the system
<code class="function">
getrusage()
</code>
call, or the
equivalent.
</p>
<p>
Since this table contains counts taken at a given point in time,
for best results it is necessary to query this table
periodically and store the results in an intermediate table or
tables. The MySQL Server's Event Scheduler can be employed
to automate such monitoring. For more information, see
<a class="xref" href="event-scheduler.html" title="27.4 Using the Event Scheduler">
Section 27.4, “Using the Event Scheduler”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-commands.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-commands">
</a>
6.5.1.2 mysql Client Commands
</h4>
</div>
</div>
</div>
<p>
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
sends each SQL statement that you issue
to the server to be executed. There is also a set of commands
that
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
itself interprets. For a list of
these commands, type
<code class="literal">
help
</code>
or
<code class="literal">
\h
</code>
at the
<code class="literal">
mysql>
</code>
prompt:
</p>
<a class="indexterm" name="idm46045317917632">
</a>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa36906371"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">mysql> help
List of all MySQL commands:
Note that all text commands must be first on line and end with ';'
? (\?) Synonym for `help'.
clear (\c) Clear the current input statement.
connect (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter.
edit (\e) Edit command with $EDITOR.
ego (\G) Send command to mysql server, display result vertically.
exit (\q) Exit mysql. Same as quit.
go (\g) Send command to mysql server.
help (\h) Display this help.
nopager (\n) Disable pager, print to stdout.
notee (\t) Don't write into outfile.
pager (\P) Set PAGER [to_pager]. Print the query results via PAGER.
print (\p) Print current command.
prompt (\R) Change your mysql prompt.
quit (\q) Quit mysql.
rehash (\#) Rebuild completion hash.
source (\.) Execute an SQL script file. Takes a file name as an argument.
status (\s) Get status information from the server.
system (\!) Execute a system shell command.
tee (\T) Set outfile [to_outfile]. Append everything into given
outfile.
use (\u) Use another database. Takes database name as argument.
charset (\C) Switch to another charset. Might be needed for processing
binlog with multi-byte charsets.
warnings (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.
resetconnection(\x) Clean session context.
query_attributes Sets string parameters (name1 value1 name2 value2 ...)
for the next query to pick up.
ssl_session_data_print Serializes the current SSL session data to stdout
or file.
For server side help, type 'help contents'</code></pre>
</div>
<p>
If
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
is invoked with the
<a class="link" href="mysql-command-options.html#option_mysql_binary-mode">
<code class="option">
--binary-mode
</code>
</a>
option, all
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
commands are disabled except
<code class="literal">
charset
</code>
and
<code class="literal">
delimiter
</code>
in
noninteractive mode (for input piped to
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
or loaded using the
<code class="literal">
source
</code>
command).
</p>
<p>
Each command has both a long and short form. The long form is
not case-sensitive; the short form is. The long form can be
followed by an optional semicolon terminator, but the short form
should not.
</p>
<p>
The use of short-form commands within multiple-line
<code class="literal">
/*
... */
</code>
comments is not supported. Short-form commands
do work within single-line
<code class="literal">
/*! ... */
</code>
version
comments, as do
<code class="literal">
/*+ ... */
</code>
optimizer-hint
comments, which are stored in object definitions. If there is a
concern that optimizer-hint comments may be stored in object
definitions so that dump files when reloaded with
<code class="literal">
mysql
</code>
would result in execution of such
commands, either invoke
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
with the
<a class="link" href="mysql-command-options.html#option_mysql_binary-mode">
<code class="option">
--binary-mode
</code>
</a>
option or use a
reload client other than
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
.
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317894480">
</a>
<a class="indexterm" name="idm46045317892992">
</a>
<code class="literal">
help [
<em class="replaceable">
<code>
arg
</code>
</em>
]
</code>
,
<code class="literal">
\h [
<em class="replaceable">
<code>
arg
</code>
</em>
]
</code>
,
<code class="literal">
\? [
<em class="replaceable">
<code>
arg
</code>
</em>
]
</code>
,
<code class="literal">
? [
<em class="replaceable">
<code>
arg
</code>
</em>
]
</code>
</p>
<p>
Display a help message listing the available
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
commands.
</p>
<p>
If you provide an argument to the
<code class="literal">
help
</code>
command,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
uses it as a search string
to access server-side help from the contents of the MySQL
Reference Manual. For more information, see
<a class="xref" href="mysql-server-side-help.html" title="6.5.1.4 mysql Client Server-Side Help">
Section 6.5.1.4, “mysql Client Server-Side Help”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317881296">
</a>
<a class="indexterm" name="idm46045317879808">
</a>
<code class="literal">
charset
<em class="replaceable">
<code>
charset_name
</code>
</em>
</code>
,
<code class="literal">
\C
<em class="replaceable">
<code>
charset_name
</code>
</em>
</code>
</p>
<p>
Change the default character set and issue a
<a class="link" href="set-names.html" title="15.7.6.3 SET NAMES Statement">
<code class="literal">
SET NAMES
</code>
</a>
statement. This
enables the character set to remain synchronized on the
client and server if
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
is run with
auto-reconnect enabled (which is not recommended), because
the specified character set is used for reconnects.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317872288">
</a>
<a class="indexterm" name="idm46045317870800">
</a>
<code class="literal">
clear
</code>
,
<code class="literal">
\c
</code>
</p>
<p>
Clear the current input. Use this if you change your mind
about executing the statement that you are entering.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317866656">
</a>
<a class="indexterm" name="idm46045317865168">
</a>
<code class="literal">
connect [
<em class="replaceable">
<code>
db_name
</code>
</em>
[
<em class="replaceable">
<code>
host_name
</code>
</em>
]]
</code>
,
<code class="literal">
\r [
<em class="replaceable">
<code>
db_name
</code>
</em>
[
<em class="replaceable">
<code>
host_name
</code>
</em>
]]
</code>
</p>
<p>
Reconnect to the server. The optional database name and host
name arguments may be given to specify the default database
or the host where the server is running. If omitted, the
current values are used.
</p>
<p>
If the
<code class="literal">
connect
</code>
command specifies a host
name argument, that host takes precedence over any
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
option given at
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
startup to specify a DNS SRV
record.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317855568">
</a>
<a class="indexterm" name="idm46045317854080">
</a>
<code class="literal">
delimiter
<em class="replaceable">
<code>
str
</code>
</em>
</code>
,
<code class="literal">
\d
<em class="replaceable">
<code>
str
</code>
</em>
</code>
</p>
<p>
Change the string that
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
interprets
as the separator between SQL statements. The default is the
semicolon character (
<code class="literal">
;
</code>
).
</p>
<p>
The delimiter string can be specified as an unquoted or
quoted argument on the
<code class="literal">
delimiter
</code>
command
line. Quoting can be done with either single quote
(
<code class="literal">
'
</code>
), double quote (
<code class="literal">
"
</code>
),
or backtick (
<code class="literal">
`
</code>
) characters. To include a
quote within a quoted string, either quote the string with a
different quote character or escape the quote with a
backslash (
<code class="literal">
\
</code>
) character. Backslash should
be avoided outside of quoted strings because it is the
escape character for MySQL. For an unquoted argument, the
delimiter is read up to the first space or end of line. For
a quoted argument, the delimiter is read up to the matching
quote on the line.
</p>
<p>
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
interprets instances of the
delimiter string as a statement delimiter anywhere it
occurs, except within quoted strings. Be careful about
defining a delimiter that might occur within other words.
For example, if you define the delimiter as
<code class="literal">
X
</code>
, it is not possible to use the word
<code class="literal">
INDEX
</code>
in statements.
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
interprets this as
<code class="literal">
INDE
</code>
followed by the delimiter
<code class="literal">
X
</code>
.
</p>
<p>
When the delimiter recognized by
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
is
set to something other than the default of
<code class="literal">
;
</code>
, instances of that character are sent
to the server without interpretation. However, the server
itself still interprets
<code class="literal">
;
</code>
as a statement
delimiter and processes statements accordingly. This
behavior on the server side comes into play for
multiple-statement execution (see
<a class="ulink" href="/doc/c-api/8.4/en/c-api-multiple-queries.html" target="_top">
Multiple Statement Execution Support
</a>
), and for parsing
the body of stored procedures and functions, triggers, and
events (see
<a class="xref" href="stored-programs-defining.html" title="27.1 Defining Stored Programs">
Section 27.1, “Defining Stored Programs”
</a>
).
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317831664">
</a>
<a class="indexterm" name="idm46045317830176">
</a>
<code class="literal">
edit
</code>
,
<code class="literal">
\e
</code>
</p>
<p>
Edit the current input statement.
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
checks the values of the
<code class="literal">
EDITOR
</code>
and
<code class="literal">
VISUAL
</code>
environment variables to determine
which editor to use. The default editor is
<span class="command">
<strong>
vi
</strong>
</span>
if neither variable is set.
</p>
<p>
The
<code class="literal">
edit
</code>
command works only in Unix.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317821504">
</a>
<a class="indexterm" name="idm46045317820016">
</a>
<code class="literal">
ego
</code>
,
<code class="literal">
\G
</code>
</p>
<p>
Send the current statement to the server to be executed and
display the result using vertical format.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317815856">
</a>
<a class="indexterm" name="idm46045317814368">
</a>
<code class="literal">
exit
</code>
,
<code class="literal">
\q
</code>
</p>
<p>
Exit
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317809120">
</a>
<a class="indexterm" name="idm46045317807632">
</a>
<code class="literal">
go
</code>
,
<code class="literal">
\g
</code>
</p>
<p>
Send the current statement to the server to be executed.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317803584">
</a>
<a class="indexterm" name="idm46045317802096">
</a>
<code class="literal">
nopager
</code>
,
<code class="literal">
\n
</code>
</p>
<p>
Disable output paging. See the description for
<code class="literal">
pager
</code>
.
</p>
<p>
The
<code class="literal">
nopager
</code>
command works only in Unix.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317796144">
</a>
<a class="indexterm" name="idm46045317794656">
</a>
<code class="literal">
notee
</code>
,
<code class="literal">
\t
</code>
</p>
<p>
Disable output copying to the tee file. See the description
for
<code class="literal">
tee
</code>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317789824">
</a>
<a class="indexterm" name="idm46045317788336">
</a>
<code class="literal">
nowarning
</code>
,
<code class="literal">
\w
</code>
</p>
<p>
Disable display of warnings after each statement.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317784208">
</a>
<a class="indexterm" name="idm46045317782720">
</a>
<code class="literal">
pager
[
<em class="replaceable">
<code>
command
</code>
</em>
]
</code>
,
<code class="literal">
\P
[
<em class="replaceable">
<code>
command
</code>
</em>
]
</code>
</p>
<p>
Enable output paging. By using the
<a class="link" href="mysql-command-options.html#option_mysql_pager">
<code class="option">
--pager
</code>
</a>
option when you invoke
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
, it is possible to browse or search
query results in interactive mode with Unix programs such as
<span class="command">
<strong>
less
</strong>
</span>
,
<span class="command">
<strong>
more
</strong>
</span>
, or any
other similar program. If you specify no value for the
option,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
checks the value of the
<code class="literal">
PAGER
</code>
environment variable and sets the
pager to that. Pager functionality works only in interactive
mode.
</p>
<p>
Output paging can be enabled interactively with the
<code class="literal">
pager
</code>
command and disabled with
<code class="literal">
nopager
</code>
. The command takes an optional
argument; if given, the paging program is set to that. With
no argument, the pager is set to the pager that was set on
the command line, or
<code class="literal">
stdout
</code>
if no pager
was specified.
</p>
<p>
Output paging works only in Unix because it uses the
<code class="literal">
popen()
</code>
function, which does not exist on
Windows. For Windows, the
<code class="literal">
tee
</code>
option can
be used instead to save query output, although it is not as
convenient as
<code class="literal">
pager
</code>
for browsing output
in some situations.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317766192">
</a>
<a class="indexterm" name="idm46045317764704">
</a>
<code class="literal">
print
</code>
,
<code class="literal">
\p
</code>
</p>
<p>
Print the current input statement without executing it.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317760576">
</a>
<a class="indexterm" name="idm46045317759088">
</a>
<code class="literal">
prompt [
<em class="replaceable">
<code>
str
</code>
</em>
]
</code>
,
<code class="literal">
\R [
<em class="replaceable">
<code>
str
</code>
</em>
]
</code>
</p>
<p>
Reconfigure the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
prompt to the given
string. The special character sequences that can be used in
the prompt are described later in this section.
</p>
<p>
If you specify the
<code class="literal">
prompt
</code>
command with no
argument,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
resets the prompt to the
default of
<code class="literal">
mysql>
</code>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317749696">
</a>
<a class="indexterm" name="idm46045317748192">
</a>
<code class="literal">
query_attributes
<em class="replaceable">
<code>
name
</code>
</em>
<em class="replaceable">
<code>
value
</code>
</em>
[
<em class="replaceable">
<code>
name
</code>
</em>
<em class="replaceable">
<code>
value
</code>
</em>
...]
</code>
</p>
<p>
Define query attributes that apply to the next query sent to
the server. For discussion of the purpose and use of query
attributes, see
<a class="xref" href="query-attributes.html" title="11.6 Query Attributes">
Section 11.6, “Query Attributes”
</a>
.
</p>
<p>
The
<code class="literal">
query_attributes
</code>
command follows
these rules:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The format and quoting rules for attribute names and
values are the same as for the
<code class="literal">
delimiter
</code>
command.
</p>
</li>
<li class="listitem">
<p>
The command permits up to 32 attribute name/value pairs.
Names and values may be up to 1024 characters long. If a
name is given without a value, an error occurs.
</p>
</li>
<li class="listitem">
<p>
If multiple
<code class="literal">
query_attributes
</code>
commands
are issued prior to query execution, only the last
command applies. After sending the query,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
clears the attribute set.
</p>
</li>
<li class="listitem">
<p>
If multiple attributes are defined with the same name,
attempts to retrieve the attribute value have an
undefined result.
</p>
</li>
<li class="listitem">
<p>
An attribute defined with an empty name cannot be
retrieved by name.
</p>
</li>
<li class="listitem">
<p>
If a reconnect occurs while
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
executes the query,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
restores
the attributes after reconnecting so the query can be
executed again with the same attributes.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317728752">
</a>
<a class="indexterm" name="idm46045317727264">
</a>
<code class="literal">
quit
</code>
,
<code class="literal">
\q
</code>
</p>
<p>
Exit
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317722016">
</a>
<a class="indexterm" name="idm46045317720528">
</a>
<code class="literal">
rehash
</code>
,
<code class="literal">
\#
</code>
</p>
<p>
Rebuild the completion hash that enables database, table,
and column name completion while you are entering
statements. (See the description for the
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
<code class="option">
--auto-rehash
</code>
</a>
option.)
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317715296">
</a>
<a class="indexterm" name="idm46045317713808">
</a>
<code class="literal">
resetconnection
</code>
,
<code class="literal">
\x
</code>
</p>
<p>
Reset the connection to clear the session state. This
includes clearing any current query attributes defined using
the
<code class="literal">
query_attributes
</code>
command.
</p>
<p>
Resetting a connection has effects similar to
<a class="ulink" href="/doc/c-api/8.4/en/mysql-change-user.html" target="_top">
<code class="literal">
mysql_change_user()
</code>
</a>
or an
auto-reconnect except that the connection is not closed and
reopened, and re-authentication is not done. See
<a class="ulink" href="/doc/c-api/8.4/en/mysql-change-user.html" target="_top">
mysql_change_user()
</a>
, and
<a class="ulink" href="/doc/c-api/8.4/en/c-api-auto-reconnect.html" target="_top">
Automatic Reconnection Control
</a>
.
</p>
<p>
This example shows how
<code class="literal">
resetconnection
</code>
clears a value maintained in the session state:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa71939571"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">LAST_INSERT_ID</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LAST_INSERT_ID(3) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">LAST_INSERT_ID</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LAST_INSERT_ID() <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> resetconnection<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">LAST_INSERT_ID</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> LAST_INSERT_ID() <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317700016">
</a>
<a class="indexterm" name="idm46045317698528">
</a>
<code class="literal">
source
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
,
<code class="literal">
\.
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</p>
<p>
Read the named file and executes the statements contained
therein. On Windows, specify path name separators as
<code class="literal">
/
</code>
or
<code class="literal">
\\
</code>
.
</p>
<p>
Quote characters are taken as part of the file name itself.
For best results, the name should not include space
characters.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317691824">
</a>
<a class="indexterm" name="idm46045317690320">
</a>
<code class="literal">
ssl_session_data_print
[
<em class="replaceable">
<code>
file_name
</code>
</em>
]
</code>
</p>
<p>
Fetches, serializes, and optionally stores the session data
of a successful connection. The optional file name and
arguments may be given to specify the file to store
serialized session data. If omitted, the session data is
printed to
<code class="literal">
stdout
</code>
.
</p>
<p>
If the MySQL session is configured for reuse, session data
from the file is deserialized and supplied to the
<code class="literal">
connect
</code>
command to reconnect. When the
session is reused successfully, the
<code class="literal">
status
</code>
command contains a row showing
<code class="literal">
SSL session reused: true
</code>
while the client
remains reconnected to the server.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317682608">
</a>
<a class="indexterm" name="idm46045317681120">
</a>
<code class="literal">
status
</code>
,
<code class="literal">
\s
</code>
</p>
<p>
Provide status information about the connection and the
server you are using. If you are running with
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--safe-updates
</code>
</a>
enabled,
<code class="literal">
status
</code>
also prints the values for the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
variables that affect your queries.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317673968">
</a>
<a class="indexterm" name="idm46045317672480">
</a>
<code class="literal">
system
<em class="replaceable">
<code>
command
</code>
</em>
</code>
,
<code class="literal">
\!
<em class="replaceable">
<code>
command
</code>
</em>
</code>
</p>
<p>
Execute the given command using your default command
interpreter.
</p>
<p>
In MySQL 8.4.3 and later, this command can be disabled by
starting the client with
<a class="link" href="mysql-command-options.html#option_mysql_system-command">
<code class="option">
--system-command=OFF
</code>
</a>
or
<a class="link" href="mysql-command-options.html#option_mysql_skip-system-command">
<code class="option">
--skip-system-command
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317665216">
</a>
<a class="indexterm" name="idm46045317663728">
</a>
<code class="literal">
tee
[
<em class="replaceable">
<code>
file_name
</code>
</em>
]
</code>
,
<code class="literal">
\T [
<em class="replaceable">
<code>
file_name
</code>
</em>
]
</code>
</p>
<p>
By using the
<a class="link" href="mysql-command-options.html#option_mysql_tee">
<code class="option">
--tee
</code>
</a>
option when
you invoke
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
, you can log statements
and their output. All the data displayed on the screen is
appended into a given file. This can be very useful for
debugging purposes also.
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
flushes
results to the file after each statement, just before it
prints its next prompt. Tee functionality works only in
interactive mode.
</p>
<p>
You can enable this feature interactively with the
<code class="literal">
tee
</code>
command. Without a parameter, the
previous file is used. The
<code class="literal">
tee
</code>
file can
be disabled with the
<code class="literal">
notee
</code>
command.
Executing
<code class="literal">
tee
</code>
again re-enables logging.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317651648">
</a>
<a class="indexterm" name="idm46045317650160">
</a>
<code class="literal">
use
<em class="replaceable">
<code>
db_name
</code>
</em>
</code>
,
<code class="literal">
\u
<em class="replaceable">
<code>
db_name
</code>
</em>
</code>
</p>
<p>
Use
<em class="replaceable">
<code>
db_name
</code>
</em>
as the default
database.
</p>
</li>
<li class="listitem">
<p>
<a class="indexterm" name="idm46045317645008">
</a>
<a class="indexterm" name="idm46045317643520">
</a>
<code class="literal">
warnings
</code>
,
<code class="literal">
\W
</code>
</p>
<p>
Enable display of warnings after each statement (if there
are any).
</p>
</li>
</ul>
</div>
<p>
Here are a few tips about the
<code class="literal">
pager
</code>
command:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
You can use it to write to a file and the results go only to
the file:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa92762626"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> pager cat <span class="token operator">></span> <span class="token operator">/</span>tmp<span class="token operator">/</span>log<span class="token punctuation">.</span>txt</code></pre>
</div>
<p>
You can also pass any options for the program that you want
to use as your pager:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa98188516"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> pager <span class="token keyword">less</span> <span class="token operator">-</span>n <span class="token operator">-</span>i <span class="token operator">-</span>S</code></pre>
</div>
</li>
<li class="listitem">
<p>
In the preceding example, note the
<code class="option">
-S
</code>
option. You may find it very useful for browsing wide query
results. Sometimes a very wide result set is difficult to
read on the screen. The
<code class="option">
-S
</code>
option to
<span class="command">
<strong>
less
</strong>
</span>
can make the result set much more
readable because you can scroll it horizontally using the
left-arrow and right-arrow keys. You can also use
<code class="option">
-S
</code>
interactively within
<span class="command">
<strong>
less
</strong>
</span>
to switch the horizontal-browse mode
on and off. For more information, read the
<span class="command">
<strong>
less
</strong>
</span>
manual page:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa39740461"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">man less</code></pre>
</div>
</li>
<li class="listitem">
<p>
The
<code class="option">
-F
</code>
and
<code class="option">
-X
</code>
options may
be used with
<span class="command">
<strong>
less
</strong>
</span>
to cause it to exit if
output fits on one screen, which is convenient when no
scrolling is necessary:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa47109329"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> pager <span class="token keyword">less</span> <span class="token operator">-</span>n <span class="token operator">-</span>i <span class="token operator">-</span>S <span class="token operator">-</span>F <span class="token operator">-</span>X</code></pre>
</div>
</li>
<li class="listitem">
<p>
You can specify very complex pager commands for handling
query output:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa98536622"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> pager cat <span class="token operator">|</span> tee <span class="token operator">/</span>dr1<span class="token operator">/</span>tmp<span class="token operator">/</span>res<span class="token punctuation">.</span>txt \
<span class="token operator">|</span> tee <span class="token operator">/</span>dr2<span class="token operator">/</span>tmp<span class="token operator">/</span>res2<span class="token punctuation">.</span>txt <span class="token operator">|</span> <span class="token keyword">less</span> <span class="token operator">-</span>n <span class="token operator">-</span>i <span class="token operator">-</span>S</code></pre>
</div>
<p>
In this example, the command would send query results to two
files in two different directories on two different file
systems mounted on
<code class="filename">
/dr1
</code>
and
<code class="filename">
/dr2
</code>
, yet still display the results
onscreen using
<span class="command">
<strong>
less
</strong>
</span>
.
</p>
</li>
</ul>
</div>
<p>
You can also combine the
<code class="literal">
tee
</code>
and
<code class="literal">
pager
</code>
functions. Have a
<code class="literal">
tee
</code>
file enabled and
<code class="literal">
pager
</code>
set to
<span class="command">
<strong>
less
</strong>
</span>
, and you are able to browse the
results using the
<span class="command">
<strong>
less
</strong>
</span>
program and still have
everything appended into a file the same time. The difference
between the Unix
<code class="literal">
tee
</code>
used with the
<code class="literal">
pager
</code>
command and the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
built-in
<code class="literal">
tee
</code>
command
is that the built-in
<code class="literal">
tee
</code>
works even if you do
not have the Unix
<span class="command">
<strong>
tee
</strong>
</span>
available. The built-in
<code class="literal">
tee
</code>
also logs everything that is printed on
the screen, whereas the Unix
<span class="command">
<strong>
tee
</strong>
</span>
used with
<code class="literal">
pager
</code>
does not log quite that much.
Additionally,
<code class="literal">
tee
</code>
file logging can be turned
on and off interactively from within
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
.
This is useful when you want to log some queries to a file, but
not others.
</p>
<a class="indexterm" name="idm46045317603792">
</a>
<p>
The
<code class="literal">
prompt
</code>
command reconfigures the default
<code class="literal">
mysql>
</code>
prompt. The string for defining the
prompt can contain the following special sequences.
</p>
<div class="informaltable">
<table summary="prompt command options that are used to configure the mysql> prompt.">
<colgroup>
<col style="width: 15%"/>
<col style="width: 75%"/>
</colgroup>
<thead>
<tr>
<th>
Option
</th>
<th>
Description
</th>
</tr>
</thead>
<tbody>
<tr>
<td>
<code class="literal">
\C
</code>
</td>
<td>
The current connection identifier
</td>
</tr>
<tr>
<td>
<code class="literal">
\c
</code>
</td>
<td>
A counter that increments for each statement you issue
</td>
</tr>
<tr>
<td>
<code class="literal">
\D
</code>
</td>
<td>
The full current date
</td>
</tr>
<tr>
<td>
<code class="literal">
\d
</code>
</td>
<td>
The default database
</td>
</tr>
<tr>
<td>
<code class="literal">
\h
</code>
</td>
<td>
The server host
</td>
</tr>
<tr>
<td>
<code class="literal">
\l
</code>
</td>
<td>
The current delimiter
</td>
</tr>
<tr>
<td>
<code class="literal">
\m
</code>
</td>
<td>
Minutes of the current time
</td>
</tr>
<tr>
<td>
<code class="literal">
\n
</code>
</td>
<td>
A newline character
</td>
</tr>
<tr>
<td>
<code class="literal">
\O
</code>
</td>
<td>
The current month in three-letter format (Jan, Feb, …)
</td>
</tr>
<tr>
<td>
<code class="literal">
\o
</code>
</td>
<td>
The current month in numeric format
</td>
</tr>
<tr>
<td>
<code class="literal">
\P
</code>
</td>
<td>
am/pm
</td>
</tr>
<tr>
<td>
<code class="literal">
\p
</code>
</td>
<td>
The current TCP/IP port or socket file
</td>
</tr>
<tr>
<td>
<code class="literal">
\R
</code>
</td>
<td>
The current time, in 24-hour military time (0–23)
</td>
</tr>
<tr>
<td>
<code class="literal">
\r
</code>
</td>
<td>
The current time, standard 12-hour time (1–12)
</td>
</tr>
<tr>
<td>
<code class="literal">
\S
</code>
</td>
<td>
Semicolon
</td>
</tr>
<tr>
<td>
<code class="literal">
\s
</code>
</td>
<td>
Seconds of the current time
</td>
</tr>
<tr>
<td>
<code class="literal">
\T
</code>
</td>
<td>
Print an asterisk (
<code class="literal">
*
</code>
) if the current session is
inside a transaction block
</td>
</tr>
<tr>
<td>
<code class="literal">
\t
</code>
</td>
<td>
A tab character
</td>
</tr>
<tr>
<td>
<code class="literal">
\U
</code>
</td>
<td>
<p>
Your full
<code class="literal">
<em class="replaceable">
<code>
user_name
</code>
</em>
@
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
account name
</p>
</td>
</tr>
<tr>
<td>
<code class="literal">
\u
</code>
</td>
<td>
Your user name
</td>
</tr>
<tr>
<td>
<code class="literal">
\v
</code>
</td>
<td>
The server version
</td>
</tr>
<tr>
<td>
<code class="literal">
\w
</code>
</td>
<td>
The current day of the week in three-letter format (Mon, Tue, …)
</td>
</tr>
<tr>
<td>
<code class="literal">
\Y
</code>
</td>
<td>
The current year, four digits
</td>
</tr>
<tr>
<td>
<code class="literal">
\y
</code>
</td>
<td>
The current year, two digits
</td>
</tr>
<tr>
<td>
<code class="literal">
\_
</code>
</td>
<td>
A space
</td>
</tr>
<tr>
<td>
<code class="literal">
\
</code>
</td>
<td>
A space (a space follows the backslash)
</td>
</tr>
<tr>
<td>
<code class="literal">
\'
</code>
</td>
<td>
Single quote
</td>
</tr>
<tr>
<td>
<code class="literal">
\"
</code>
</td>
<td>
Double quote
</td>
</tr>
<tr>
<td>
<code class="literal">
\\
</code>
</td>
<td>
A literal
<code class="literal">
\
</code>
backslash character
</td>
</tr>
<tr>
<td>
<code class="literal">
\
<em class="replaceable">
<code>
x
</code>
</em>
</code>
</td>
<td>
<p>
<em class="replaceable">
<code>
x
</code>
</em>
, for any
<span class="quote">
“
<span class="quote">
<em class="replaceable">
<code>
x
</code>
</em>
</span>
”
</span>
not listed
above
</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="informaltable">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 590px;">
<thead>
<tr>
<th style="width: 98.1094px;">
Option
</th>
<th style="width: 490.547px;">
Description
</th>
</tr>
</thead>
</table>
</div>
<p>
You can set the prompt in several ways:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="emphasis">
<em>
Use an environment variable.
</em>
</span>
You can
set the
<code class="literal">
MYSQL_PS1
</code>
environment variable to
a prompt string. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa98774392"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">export MYSQL_PS1=<span class="token atrule">"(\u@\h) [\d]> "</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<span class="emphasis">
<em>
Use a command-line option.
</em>
</span>
You can set
the
<a class="link" href="mysql-command-options.html#option_mysql_prompt">
<code class="option">
--prompt
</code>
</a>
option on the
command line to
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa21611396"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token constant">--prompt</span>=<span class="token atrule">"(\u@\h) [\d]> "</span>
<span class="token punctuation">(</span>user@host<span class="token punctuation">)</span> <span class="token punctuation">[</span>database<span class="token punctuation">]</span>></code></pre>
</div>
</li>
<li class="listitem">
<p>
<span class="emphasis">
<em>
Use an option file.
</em>
</span>
You can set the
<code class="literal">
prompt
</code>
option in the
<code class="literal">
[mysql]
</code>
group of any MySQL option file,
such as
<code class="filename">
/etc/my.cnf
</code>
or the
<code class="filename">
.my.cnf
</code>
file in your home directory.
For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa96201781"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysql]</span>
<span class="token constant">prompt</span><span class="token attr-value"><span class="token punctuation">=</span>(\\u@\\h) [\\d]>\\_</span></code></pre>
</div>
<p>
In this example, note that the backslashes are doubled. If
you set the prompt using the
<code class="literal">
prompt
</code>
option in an option file, it is advisable to double the
backslashes when using the special prompt options. There is
some overlap in the set of permissible prompt options and
the set of special escape sequences that are recognized in
option files. (The rules for escape sequences in option
files are listed in
<a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files">
Section 6.2.2.2, “Using Option Files”
</a>
.) The
overlap may cause you problems if you use single
backslashes. For example,
<code class="literal">
\s
</code>
is
interpreted as a space rather than as the current seconds
value. The following example shows how to define a prompt
within an option file to include the current time in
<code class="literal">
<em class="replaceable">
<code>
hh:mm:ss
</code>
</em>
>
</code>
format:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-ini"><div class="docs-select-all right" id="sa23724366"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysql]</span>
<span class="token constant">prompt</span><span class="token attr-value"><span class="token punctuation">=</span>"\\r:\\m:\\s> "</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<span class="emphasis">
<em>
Set the prompt interactively.
</em>
</span>
You can
change your prompt interactively by using the
<code class="literal">
prompt
</code>
(or
<code class="literal">
\R
</code>
)
command. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37341924"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> prompt <span class="token punctuation">(</span>\u@\h<span class="token punctuation">)</span> <span class="token punctuation">[</span>\d<span class="token punctuation">]</span><span class="token operator">></span>\_
PROMPT <span class="token keyword">set</span> <span class="token keyword">to</span> <span class="token string">'(\u@\h) [\d]>\_'</span>
<span class="token punctuation">(</span><span class="token keyword"><em class="replaceable">user</em></span><span class="token variable">@<em class="replaceable">host</em></span><span class="token punctuation">)</span> <span class="token punctuation">[</span><span class="token keyword"><em class="replaceable">database</em></span><span class="token punctuation">]</span><span class="token operator">></span>
<span class="token punctuation">(</span><span class="token keyword"><em class="replaceable">user</em></span><span class="token variable">@<em class="replaceable">host</em></span><span class="token punctuation">)</span> <span class="token punctuation">[</span><span class="token keyword"><em class="replaceable">database</em></span><span class="token punctuation">]</span><span class="token operator">></span> prompt
<span class="token keyword">Returning</span> <span class="token keyword">to</span> <span class="token keyword">default</span> PROMPT <span class="token keyword">of</span> mysql<span class="token operator">></span>
<span class="token prompt">mysql></span></code></pre>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/gis-class-point.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="gis-class-point">
</a>
13.4.2.3 Point Class
</h4>
</div>
</div>
</div>
<p>
A
<code class="literal">
Point
</code>
is a geometry that represents a
single location in coordinate space.
</p>
<p>
<span class="bold">
<strong>
<code class="literal">
Point
</code>
Examples
</strong>
</span>
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Imagine a large-scale map of the world with many cities. A
<code class="literal">
Point
</code>
object could represent each city.
</p>
</li>
<li class="listitem">
<p>
On a city map, a
<code class="literal">
Point
</code>
object could
represent a bus stop.
</p>
</li>
</ul>
</div>
<p>
<span class="bold">
<strong>
<code class="literal">
Point
</code>
Properties
</strong>
</span>
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
X-coordinate value.
</p>
</li>
<li class="listitem">
<p>
Y-coordinate value.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
Point
</code>
is defined as a zero-dimensional
geometry.
</p>
</li>
<li class="listitem">
<p>
The boundary of a
<code class="literal">
Point
</code>
is the empty
set.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-compression-syntax-warnings.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="innodb-compression-syntax-warnings">
</a>
17.9.1.7 SQL Compression Syntax Warnings and Errors
</h4>
</div>
</div>
</div>
<p>
This section describes syntax warnings and errors that you may
encounter when using the table compression feature with
<a class="link" href="glossary.html#glos_file_per_table" title="file-per-table">
file-per-table
</a>
tablespaces and
<a class="link" href="glossary.html#glos_general_tablespace" title="general tablespace">
general
tablespaces
</a>
.
</p>
<h5>
<a name="idm46045161324368">
</a>
SQL Compression Syntax Warnings and Errors for File-Per-Table
Tablespaces
</h5>
<p>
When
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is
enabled (the default), specifying
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
or
<code class="literal">
KEY_BLOCK_SIZE
</code>
in
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE
TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
statements produces the following error if
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
is
disabled.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa55171768"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token output">ERROR 1031 (HY000)<span class="token punctuation">:</span> Table storage engine for 't1' doesn't have this option</span></code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The table is not created if the current configuration does not
permit using compressed tables.
</p>
</div>
<p>
When
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is
disabled, specifying
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
or
<code class="literal">
KEY_BLOCK_SIZE
</code>
in
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE
TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
statements produces the following warnings if
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
is
disabled.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa83783905"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">WARNINGS</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Level <span class="token punctuation">|</span> Code <span class="token punctuation">|</span> Message <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> Warning <span class="token punctuation">|</span> 1478 <span class="token punctuation">|</span> InnoDB: KEY_BLOCK_SIZE requires innodb_file_per_table. <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Warning <span class="token punctuation">|</span> 1478 <span class="token punctuation">|</span> InnoDB: ignoring KEY_BLOCK_SIZE=4. <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Warning <span class="token punctuation">|</span> 1478 <span class="token punctuation">|</span> InnoDB: ROW_FORMAT=COMPRESSED requires innodb_file_per_table. <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> Warning <span class="token punctuation">|</span> 1478 <span class="token punctuation">|</span> InnoDB: assuming ROW_FORMAT=DYNAMIC. <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
These messages are only warnings, not errors, and the table is
created without compression, as if the options were not
specified.
</p>
</div>
<p>
The
<span class="quote">
“
<span class="quote">
non-strict
</span>
”
</span>
behavior lets you import a
<code class="literal">
mysqldump
</code>
file into a database that does not
support compressed tables, even if the source database contained
compressed tables. In that case, MySQL creates the table in
<code class="literal">
ROW_FORMAT=DYNAMIC
</code>
instead of preventing the
operation.
</p>
<p>
To import the dump file into a new database, and have the tables
re-created as they exist in the original database, ensure the
server has the proper setting for the
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
configuration parameter.
</p>
<p>
The attribute
<code class="literal">
KEY_BLOCK_SIZE
</code>
is permitted
only when
<code class="literal">
ROW_FORMAT
</code>
is specified as
<code class="literal">
COMPRESSED
</code>
or is omitted. Specifying a
<code class="literal">
KEY_BLOCK_SIZE
</code>
with any other
<code class="literal">
ROW_FORMAT
</code>
generates a warning that you can
view with
<code class="literal">
SHOW WARNINGS
</code>
. However, the table
is non-compressed; the specified
<code class="literal">
KEY_BLOCK_SIZE
</code>
is ignored).
</p>
<div class="informaltable">
<table summary="Warning level, error code, and message text for messages that could be generated when using conflicting clauses for InnoDB table compression.">
<colgroup>
<col style="width: 20%"/>
<col style="width: 20%"/>
<col style="width: 60%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Level
</th>
<th scope="col">
Code
</th>
<th scope="col">
Message
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
Warning
</th>
<td>
1478
</td>
<td>
<code class="literal">
InnoDB: ignoring KEY_BLOCK_SIZE=
<em class="replaceable">
<code>
n
</code>
</em>
unless ROW_FORMAT=COMPRESSED.
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
If you are running with
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
enabled, the
combination of a
<code class="literal">
KEY_BLOCK_SIZE
</code>
with any
<code class="literal">
ROW_FORMAT
</code>
other than
<code class="literal">
COMPRESSED
</code>
generates an error, not a warning,
and the table is not created.
</p>
<p>
<a class="xref" href="innodb-compression-syntax-warnings.html#innodb-compression-create-and-alter-options-table" title="Table 17.11 ROW_FORMAT and KEY_BLOCK_SIZE Options">
Table 17.11, “ROW_FORMAT and KEY_BLOCK_SIZE Options”
</a>
provides an overview the
<code class="literal">
ROW_FORMAT
</code>
and
<code class="literal">
KEY_BLOCK_SIZE
</code>
options that are used with
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
.
</p>
<div class="table">
<a name="innodb-compression-create-and-alter-options-table">
</a>
<p class="title">
<b>
Table 17.11 ROW_FORMAT and KEY_BLOCK_SIZE Options
</b>
</p>
<div class="table-contents">
<table summary="ROW_FORMAT and KEY_BLOCK_SIZE option usage notes and descriptions.">
<colgroup>
<col style="width: 20%"/>
<col style="width: 40%"/>
<col style="width: 40%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Option
</th>
<th scope="col">
Usage Notes
</th>
<th scope="col">
Description
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=REDUNDANT
</code>
</th>
<td>
Storage format used prior to MySQL 5.0.3
</td>
<td>
Less efficient than
<code class="literal">
ROW_FORMAT=COMPACT
</code>
; for backward
compatibility
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=COMPACT
</code>
</th>
<td>
Default storage format since MySQL 5.0.3
</td>
<td>
Stores a prefix of 768 bytes of long column values in the clustered
index page, with the remaining bytes stored in an overflow
page
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=DYNAMIC
</code>
</th>
<td>
</td>
<td>
Store values within the clustered index page if they fit; if not, stores
only a 20-byte pointer to an overflow page (no prefix)
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
</th>
<td>
</td>
<td>
Compresses the table and indexes using zlib
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
KEY_BLOCK_SIZE=
<em class="replaceable">
<code>
n
</code>
</em>
</code>
</th>
<td>
</td>
<td>
Specifies compressed page size of 1, 2, 4, 8 or 16 kilobytes; implies
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
. For general
tablespaces, a
<code class="literal">
KEY_BLOCK_SIZE
</code>
value
equal to the
<code class="literal">
InnoDB
</code>
page size is not
permitted.
</td>
</tr>
</tbody>
</table>
</div>
</div>
<br class="table-break"/>
<p>
<a class="xref" href="innodb-compression-syntax-warnings.html#innodb-compression-create-and-alter-errors-table" title="Table 17.12 CREATE/ALTER TABLE Warnings and Errors when InnoDB Strict Mode is OFF">
Table 17.12, “CREATE/ALTER TABLE Warnings and Errors when InnoDB Strict Mode is OFF”
</a>
summarizes error conditions that occur with certain combinations
of configuration parameters and options on the
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
or
<a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
<code class="literal">
ALTER TABLE
</code>
</a>
statements, and how
the options appear in the output of
<code class="literal">
SHOW TABLE
STATUS
</code>
.
</p>
<p>
When
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is
<code class="literal">
OFF
</code>
, MySQL creates or alters the table, but
ignores certain settings as shown below. You can see the warning
messages in the MySQL error log. When
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is
<code class="literal">
ON
</code>
, these specified combinations of options
generate errors, and the table is not created or altered. To see
the full description of the error condition, issue the
<code class="literal">
SHOW ERRORS
</code>
statement: example:
</p>
<pre class="screen">mysql> <strong class="userinput"><code>CREATE TABLE x (id INT PRIMARY KEY, c INT)</code></strong>
-> <strong class="userinput"><code>ENGINE=INNODB KEY_BLOCK_SIZE=33333;</code></strong>
ERROR 1005 (HY000): Can't create table 'test.x' (errno: 1478)
mysql> <strong class="userinput"><code>SHOW ERRORS;</code></strong>
+-------+------+-------------------------------------------+
| Level | Code | Message |
+-------+------+-------------------------------------------+
| Error | 1478 | InnoDB: invalid KEY_BLOCK_SIZE=33333. |
| Error | 1005 | Can't create table 'test.x' (errno: 1478) |
+-------+------+-------------------------------------------+
</pre>
<p>
</p>
<div class="table">
<a name="innodb-compression-create-and-alter-errors-table">
</a>
<p class="title">
<b>
Table 17.12 CREATE/ALTER TABLE Warnings and Errors when InnoDB Strict Mode is OFF
</b>
</p>
<div class="table-contents">
<table summary="CREATE and ALTER TABLE warnings and errors when InnoDB strict mode is OFF.">
<colgroup>
<col style="width: 33%"/>
<col style="width: 33%"/>
<col style="width: 33%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Syntax
</th>
<th scope="col">
Warning or Error Condition
</th>
<th scope="col">
Resulting
<code class="literal">
ROW_FORMAT
</code>
, as shown in
<code class="literal">
SHOW TABLE
STATUS
</code>
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=REDUNDANT
</code>
</th>
<td>
None
</td>
<td>
<code class="literal">
REDUNDANT
</code>
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=COMPACT
</code>
</th>
<td>
None
</td>
<td>
<code class="literal">
COMPACT
</code>
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
or
<code class="literal">
ROW_FORMAT=DYNAMIC
</code>
or
<code class="literal">
KEY_BLOCK_SIZE
</code>
is specified
</th>
<td>
Ignored for file-per-table tablespaces unless
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
is
enabled. General tablespaces support all row formats. See
<a class="xref" href="general-tablespaces.html" title="17.6.3.3 General Tablespaces">
Section 17.6.3.3, “General Tablespaces”
</a>
.
</td>
<td>
<code class="literal">
the default row format for file-per-table tablespaces; the
specified row format for general tablespaces
</code>
</td>
</tr>
<tr>
<th scope="row">
Invalid
<code class="literal">
KEY_BLOCK_SIZE
</code>
is specified (not 1, 2, 4, 8
or 16)
</th>
<td>
<code class="literal">
KEY_BLOCK_SIZE
</code>
is ignored
</td>
<td>
the specified row format, or the default row format
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT=COMPRESSED
</code>
and valid
<code class="literal">
KEY_BLOCK_SIZE
</code>
are specified
</th>
<td>
None;
<code class="literal">
KEY_BLOCK_SIZE
</code>
specified is used
</td>
<td>
<code class="literal">
COMPRESSED
</code>
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
KEY_BLOCK_SIZE
</code>
is specified with
<code class="literal">
REDUNDANT
</code>
,
<code class="literal">
COMPACT
</code>
or
<code class="literal">
DYNAMIC
</code>
row format
</th>
<td>
<code class="literal">
KEY_BLOCK_SIZE
</code>
is ignored
</td>
<td>
<code class="literal">
REDUNDANT
</code>
,
<code class="literal">
COMPACT
</code>
or
<code class="literal">
DYNAMIC
</code>
</td>
</tr>
<tr>
<th scope="row">
<code class="literal">
ROW_FORMAT
</code>
is not one of
<code class="literal">
REDUNDANT
</code>
,
<code class="literal">
COMPACT
</code>
,
<code class="literal">
DYNAMIC
</code>
or
<code class="literal">
COMPRESSED
</code>
</th>
<td>
Ignored if recognized by the MySQL parser. Otherwise, an error is
issued.
</td>
<td>
the default row format or N/A
</td>
</tr>
</tbody>
</table>
</div>
</div>
<br class="table-break"/>
<p>
When
<code class="literal">
innodb_strict_mode
</code>
is
<code class="literal">
ON
</code>
, MySQL rejects invalid
<code class="literal">
ROW_FORMAT
</code>
or
<code class="literal">
KEY_BLOCK_SIZE
</code>
parameters and issues errors.
Strict mode is
<code class="literal">
ON
</code>
by default. When
<code class="literal">
innodb_strict_mode
</code>
is
<code class="literal">
OFF
</code>
,
MySQL issues warnings instead of errors for ignored invalid
parameters.
</p>
<p>
It is not possible to see the chosen
<code class="literal">
KEY_BLOCK_SIZE
</code>
using
<code class="literal">
SHOW TABLE
STATUS
</code>
. The statement
<code class="literal">
SHOW CREATE
TABLE
</code>
displays the
<code class="literal">
KEY_BLOCK_SIZE
</code>
(even if it was ignored when creating the table). The real
compressed page size of the table cannot be displayed by MySQL.
</p>
<h5>
<a name="idm46045161169424">
</a>
SQL Compression Syntax Warnings and Errors for General Tablespaces
</h5>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
If
<code class="literal">
FILE_BLOCK_SIZE
</code>
was not defined for
the general tablespace when the tablespace was created, the
tablespace cannot contain compressed tables. If you attempt
to add a compressed table, an error is returned, as shown in
the following example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa16191071"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPRESSED</span>
<span class="token keyword">KEY_BLOCK_SIZE</span><span class="token operator">=</span><span class="token number">8</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1478 (HY000)<span class="token punctuation">:</span> InnoDB<span class="token punctuation">:</span> Tablespace `ts1` cannot contain a COMPRESSED table</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Attempting to add a table with an invalid
<code class="literal">
KEY_BLOCK_SIZE
</code>
to a general tablespace
returns an error, as shown in the following example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3489471"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts2<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts2.ibd'</span> <span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token number">8192</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts2 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPRESSED</span>
<span class="token keyword">KEY_BLOCK_SIZE</span><span class="token operator">=</span><span class="token number">4</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1478 (HY000)<span class="token punctuation">:</span> InnoDB<span class="token punctuation">:</span> Tablespace `ts2` uses block size 8192 and cannot
contain a table with physical page size 4096</span></code></pre>
</div>
<p>
For general tablespaces, the
<code class="literal">
KEY_BLOCK_SIZE
</code>
of the table must be equal
to the
<code class="literal">
FILE_BLOCK_SIZE
</code>
of the tablespace
divided by 1024. For example, if the
<code class="literal">
FILE_BLOCK_SIZE
</code>
of the tablespace is
8192, the
<code class="literal">
KEY_BLOCK_SIZE
</code>
of the table
must be 8.
</p>
</li>
<li class="listitem">
<p>
Attempting to add a table with an uncompressed row format to
a general tablespace configured to store compressed tables
returns an error, as shown in the following example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24810483"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts3<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts3.ibd'</span> <span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token number">8192</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span>
<span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts3 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPACT</span><span class="token punctuation">;</span>
<span class="token output">ERROR 1478 (HY000)<span class="token punctuation">:</span> InnoDB<span class="token punctuation">:</span> Tablespace `ts3` uses block size 8192 and cannot
contain a table with physical page size 16384</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
is not
applicable to general tablespaces. Tablespace management rules
for general tablespaces are strictly enforced independently of
<a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode">
<code class="literal">
innodb_strict_mode
</code>
</a>
. For more
information, see
<a class="xref" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement">
Section 15.1.21, “CREATE TABLESPACE Statement”
</a>
.
</p>
<p>
For more information about using compressed tables with general
tablespaces, see
<a class="xref" href="general-tablespaces.html" title="17.6.3.3 General Tablespaces">
Section 17.6.3.3, “General Tablespaces”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/explain-extended.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="explain-extended">
</a>
10.8.3 Extended EXPLAIN Output Format
</h3>
</div>
</div>
</div>
<p>
The
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
statement produces
extra (
<span class="quote">
“
<span class="quote">
extended
</span>
”
</span>
) information that is not part of
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
output but can be viewed
by issuing a
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW WARNINGS
</code>
</a>
statement following
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
.
Extended information is available for
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
,
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
,
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
, and
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statements.
</p>
<p>
The
<code class="literal">
Message
</code>
value in
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW WARNINGS
</code>
</a>
output displays how
the optimizer qualifies table and column names in the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statement, what the
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
looks like after the
application of rewriting and optimization rules, and possibly
other notes about the optimization process.
</p>
<p>
The extended information displayable with a
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW WARNINGS
</code>
</a>
statement following
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
is produced only for
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements.
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW WARNINGS
</code>
</a>
displays an empty
result for other explainable statements
(
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
,
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
,
<a class="link" href="replace.html" title="15.2.12 REPLACE Statement">
<code class="literal">
REPLACE
</code>
</a>
, and
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
).
</p>
<p>
Here is an example of extended
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
output:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa26569812"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">EXPLAIN</span>
<span class="token keyword">SELECT</span> t1<span class="token punctuation">.</span>a<span class="token punctuation">,</span> t1<span class="token punctuation">.</span>a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> t2<span class="token punctuation">.</span>a <span class="token keyword">FROM</span> t2<span class="token punctuation">)</span> <span class="token keyword">FROM</span> t1\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
id<span class="token punctuation">:</span> 1
select_type<span class="token punctuation">:</span> PRIMARY
table<span class="token punctuation">:</span> t1
type<span class="token punctuation">:</span> index
possible_keys<span class="token punctuation">:</span> NULL
key<span class="token punctuation">:</span> PRIMARY
key_len<span class="token punctuation">:</span> 4
ref<span class="token punctuation">:</span> NULL
rows<span class="token punctuation">:</span> 4
filtered<span class="token punctuation">:</span> 100.00
Extra<span class="token punctuation">:</span> Using index
<span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 2. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
id<span class="token punctuation">:</span> 2
select_type<span class="token punctuation">:</span> SUBQUERY
table<span class="token punctuation">:</span> t2
type<span class="token punctuation">:</span> index
possible_keys<span class="token punctuation">:</span> a
key<span class="token punctuation">:</span> a
key_len<span class="token punctuation">:</span> 5
ref<span class="token punctuation">:</span> NULL
rows<span class="token punctuation">:</span> 3
filtered<span class="token punctuation">:</span> 100.00
Extra<span class="token punctuation">:</span> Using index
</span><span class="token output">2 rows in set, 1 warning (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">WARNINGS</span>\G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
Level<span class="token punctuation">:</span> Note
Code<span class="token punctuation">:</span> 1003
Message<span class="token punctuation">:</span> /<span class="token punctuation">*</span> select#1 <span class="token punctuation">*</span>/ select `test`.`t1`.`a` AS `a`,
<in_optimizer>(`test`.`t1`.`a`,`test`.`t1`.`a` in
( <materialize> (/<span class="token punctuation">*</span> select#2 <span class="token punctuation">*</span>/ select `test`.`t2`.`a`
from `test`.`t2` where 1 having 1 ),
<primary_index_lookup>(`test`.`t1`.`a` in
<temporary table> on <auto_key>
where ((`test`.`t1`.`a` = `materialized-subquery`.`a`))))) AS `t1.a
IN (SELECT t2.a FROM t2)` from `test`.`t1`
</span><span class="token output">1 row in set (0.00 sec)</span></code></pre>
</div>
<p>
Because the statement displayed by
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW
WARNINGS
</code>
</a>
may contain special markers to provide
information about query rewriting or optimizer actions, the
statement is not necessarily valid SQL and is not intended to be
executed. The output may also include rows with
<code class="literal">
Message
</code>
values that provide additional
non-SQL explanatory notes about actions taken by the optimizer.
</p>
<p>
The following list describes special markers that can appear in
the extended output displayed by
<a class="link" href="show-warnings.html" title="15.7.7.42 SHOW WARNINGS Statement">
<code class="literal">
SHOW
WARNINGS
</code>
</a>
:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
<auto_key>
</code>
</p>
<p>
An automatically generated key for a temporary table.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<cache>(
<em class="replaceable">
<code>
expr
</code>
</em>
)
</code>
</p>
<p>
The expression (such as a scalar subquery) is executed once
and the resulting value is saved in memory for later use.
For results consisting of multiple values, a temporary table
may be created and
<code class="literal">
<temporary
table>
</code>
is shown instead.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<exists>(
<em class="replaceable">
<code>
query
fragment
</code>
</em>
)
</code>
</p>
<p>
The subquery predicate is converted to an
<code class="literal">
EXISTS
</code>
predicate and the subquery is
transformed so that it can be used together with the
<code class="literal">
EXISTS
</code>
predicate.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<in_optimizer>(
<em class="replaceable">
<code>
query
fragment
</code>
</em>
)
</code>
</p>
<p>
This is an internal optimizer object with no user
significance.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<index_lookup>(
<em class="replaceable">
<code>
query
fragment
</code>
</em>
)
</code>
</p>
<p>
The query fragment is processed using an index lookup to
find qualifying rows.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<if>(
<em class="replaceable">
<code>
condition
</code>
</em>
,
<em class="replaceable">
<code>
expr1
</code>
</em>
,
<em class="replaceable">
<code>
expr2
</code>
</em>
)
</code>
</p>
<p>
If the condition is true, evaluate to
<em class="replaceable">
<code>
expr1
</code>
</em>
, otherwise
<em class="replaceable">
<code>
expr2
</code>
</em>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<is_not_null_test>(
<em class="replaceable">
<code>
expr
</code>
</em>
)
</code>
</p>
<p>
A test to verify that the expression does not evaluate to
<code class="literal">
NULL
</code>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<materialize>(
<em class="replaceable">
<code>
query
fragment
</code>
</em>
)
</code>
</p>
<p>
Subquery materialization is used.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
`materialized-subquery`.
<em class="replaceable">
<code>
col_name
</code>
</em>
</code>
</p>
<p>
A reference to the column
<em class="replaceable">
<code>
col_name
</code>
</em>
in an internal temporary
table materialized to hold the result from evaluating a
subquery.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<primary_index_lookup>(
<em class="replaceable">
<code>
query
fragment
</code>
</em>
)
</code>
</p>
<p>
The query fragment is processed using a primary key lookup
to find qualifying rows.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<ref_null_helper>(
<em class="replaceable">
<code>
expr
</code>
</em>
)
</code>
</p>
<p>
This is an internal optimizer object with no user
significance.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
/* select#
<em class="replaceable">
<code>
N
</code>
</em>
*/
<em class="replaceable">
<code>
select_stmt
</code>
</em>
</code>
</p>
<p>
The
<code class="literal">
SELECT
</code>
is associated with the row in
non-extended
<a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement">
<code class="literal">
EXPLAIN
</code>
</a>
output
that has an
<code class="literal">
id
</code>
value of
<em class="replaceable">
<code>
N
</code>
</em>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<em class="replaceable">
<code>
outer_tables
</code>
</em>
semi join
(
<em class="replaceable">
<code>
inner_tables
</code>
</em>
)
</code>
</p>
<p>
A semijoin operation.
<em class="replaceable">
<code>
inner_tables
</code>
</em>
shows the tables
that were not pulled out. See
<a class="ulink" href="/doc/refman/8.0/en/semijoins.html" target="_top">
Optimizing IN and EXISTS Subquery Predicates with Semijoin Transformations
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
<temporary table>
</code>
</p>
<p>
This represents an internal temporary table created to cache
an intermediate result.
</p>
</li>
</ul>
</div>
<p>
When some tables are of
<a class="link" href="explain-output.html#jointype_const">
<code class="literal">
const
</code>
</a>
or
<a class="link" href="explain-output.html#jointype_system">
<code class="literal">
system
</code>
</a>
type, expressions
involving columns from these tables are evaluated early by the
optimizer and are not part of the displayed statement. However,
with
<code class="literal">
FORMAT=JSON
</code>
, some
<a class="link" href="explain-output.html#jointype_const">
<code class="literal">
const
</code>
</a>
table accesses are
displayed as a
<a class="link" href="explain-output.html#jointype_ref">
<code class="literal">
ref
</code>
</a>
access
that uses a const value.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/ddl-rewriter-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="ddl-rewriter-options">
</a>
7.6.5.2 ddl_rewriter Plugin Options
</h4>
</div>
</div>
</div>
<p>
This section describes the command options that control
operation of the
<code class="literal">
ddl_rewriter
</code>
plugin. If
values specified at startup time are incorrect, the
<code class="literal">
ddl_rewriter
</code>
plugin may fail to initialize
properly and the server does not load it.
</p>
<p>
To control activation of the
<code class="literal">
ddl_rewriter
</code>
plugin, use this option:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="option_mysqld_ddl-rewriter">
</a>
<a class="link" href="ddl-rewriter-options.html#option_mysqld_ddl-rewriter">
<code class="option">
--ddl-rewriter[=
<em class="replaceable">
<code>
value
</code>
</em>
]
</code>
</a>
</p>
<a class="indexterm" name="idm46045256158784">
</a>
<a class="indexterm" name="idm46045256157296">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for ddl-rewriter">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--ddl-rewriter[=value]
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Enumeration
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
ON
</code>
</td>
</tr>
<tr>
<th>
Valid Values
</th>
<td>
<p class="valid-value">
<code class="literal">
ON
</code>
</p>
<p class="valid-value">
<code class="literal">
OFF
</code>
</p>
<p class="valid-value">
<code class="literal">
FORCE
</code>
</p>
<p class="valid-value">
<code class="literal">
FORCE_PLUS_PERMANENT
</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<p>
This option controls how the server loads the
<code class="literal">
ddl_rewriter
</code>
plugin at startup. It is
available only if the plugin has been previously registered
with
<a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement">
<code class="literal">
INSTALL PLUGIN
</code>
</a>
or is
loaded with
<a class="link" href="server-options.html#option_mysqld_plugin-load">
<code class="option">
--plugin-load
</code>
</a>
or
<a class="link" href="server-options.html#option_mysqld_plugin-load-add">
<code class="option">
--plugin-load-add
</code>
</a>
. See
<a class="xref" href="ddl-rewriter-installation.html" title="7.6.5.1 Installing or Uninstalling ddl_rewriter">
Section 7.6.5.1, “Installing or Uninstalling ddl_rewriter”
</a>
.
</p>
<p>
The option value should be one of those available for
plugin-loading options, as described in
<a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins">
Section 7.6.1, “Installing and Uninstalling Plugins”
</a>
. For example,
<a class="link" href="ddl-rewriter-options.html#option_mysqld_ddl-rewriter">
<code class="option">
--ddl-rewriter=OFF
</code>
</a>
disables
the plugin at server startup.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-disk-data-storage-requirements.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-cluster-disk-data-storage-requirements">
</a>
25.6.11.2 NDB Cluster Disk Data Storage Requirements
</h4>
</div>
</div>
</div>
<p>
<a class="indexterm" name="idm46045091519280">
</a>
The following items apply to Disk Data storage requirements:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Variable-length columns of Disk Data tables take up a fixed
amount of space. For each row, this is equal to the space
required to store the largest possible value for that
column.
</p>
<p>
For general information about calculating these values, see
<a class="xref" href="storage-requirements.html" title="13.7 Data Type Storage Requirements">
Section 13.7, “Data Type Storage Requirements”
</a>
.
</p>
<p>
You can obtain an estimate the amount of space available in
data files and undo log files by querying the Information
Schema
<a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
<code class="literal">
FILES
</code>
</a>
table. For more
information and examples, see
<a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table">
Section 28.3.15, “The INFORMATION_SCHEMA FILES Table”
</a>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The
<a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement">
<code class="literal">
OPTIMIZE TABLE
</code>
</a>
statement does not have any effect on Disk Data tables.
</p>
</div>
</li>
<li class="listitem">
<p>
In a Disk Data table, the first 256 bytes of a
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
TEXT
</code>
</a>
or
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
BLOB
</code>
</a>
column are stored in
memory; only the remainder is stored on disk.
</p>
</li>
<li class="listitem">
<p>
Each row in a Disk Data table uses 8 bytes in memory to
point to the data stored on disk. This means that, in some
cases, converting an in-memory column to the disk-based
format can actually result in greater memory usage. For
example, converting a
<code class="literal">
CHAR(4)
</code>
column from
memory-based to disk-based format increases the amount of
<a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory">
<code class="literal">
DataMemory
</code>
</a>
used per
row from 4 to 8 bytes.
</p>
</li>
</ul>
</div>
<div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Important
</div>
<p>
Starting the cluster with the
<code class="option">
--initial
</code>
option does
<span class="emphasis">
<em>
not
</em>
</span>
remove Disk Data files.
You must remove these manually prior to performing an initial
restart of the cluster.
</p>
</div>
<p>
Performance of Disk Data tables can be improved by minimizing
the number of disk seeks by making sure that
<a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebuffermemory">
<code class="literal">
DiskPageBufferMemory
</code>
</a>
is
of sufficient size. You can query the
<a class="link" href="mysql-cluster-ndbinfo-diskpagebuffer.html" title="25.6.17.31 The ndbinfo diskpagebuffer Table">
<code class="literal">
diskpagebuffer
</code>
</a>
table to help
determine whether the value for this parameter needs to be
increased.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/what-is.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="what-is">
</a>
1.2 Overview of the MySQL Database Management System
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="what-is-mysql.html">
1.2.1 What is MySQL?
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="features.html">
1.2.2 The Main Features of MySQL
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="history.html">
1.2.3 History of MySQL
</a>
</span>
</dt>
</dl>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sys-ps-thread-id.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="sys-ps-thread-id">
</a>
30.4.5.15 The ps_thread_id() Function
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045060784384">
</a>
<a class="indexterm" name="idm46045060782928">
</a>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
<a class="link" href="sys-ps-thread-id.html" title="30.4.5.15 The ps_thread_id() Function">
<code class="literal">
ps_thread_id()
</code>
</a>
is deprecated,
and subject to removal in a future MySQL version.
Applications that use it should be migrated to use the
built-in
<a class="link" href="performance-schema-functions.html#function_ps-thread-id">
<code class="literal">
PS_THREAD_ID()
</code>
</a>
and
<a class="link" href="performance-schema-functions.html#function_ps-current-thread-id">
<code class="literal">
PS_CURRENT_THREAD_ID()
</code>
</a>
functions instead. See
<a class="xref" href="performance-schema-functions.html" title="14.21 Performance Schema Functions">
Section 14.21, “Performance Schema Functions”
</a>
</p>
</div>
<p>
Returns the Performance Schema thread ID assigned to a given
connection ID, or the thread ID for the current connection if
the connection ID is
<code class="literal">
NULL
</code>
.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="sys-ps-thread-id-parameters">
</a>
Parameters
</h5>
</div>
</div>
</div>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
in_connection_id BIGINT UNSIGNED
</code>
: The
ID of the connection for which to return the thread ID.
This is a value of the type given in the
<code class="literal">
PROCESSLIST_ID
</code>
column of the
Performance Schema
<a class="link" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table">
<code class="literal">
threads
</code>
</a>
table or the
<code class="literal">
Id
</code>
column of
<a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement">
<code class="literal">
SHOW PROCESSLIST
</code>
</a>
output.
</p>
</li>
</ul>
</div>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="sys-ps-thread-id-return-value">
</a>
Return Value
</h5>
</div>
</div>
</div>
<p>
A
<code class="literal">
BIGINT UNSIGNED
</code>
value.
</p>
</div>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="sys-ps-thread-id-example">
</a>
Example
</h5>
</div>
</div>
</div>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69682178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>ps_thread_id<span class="token punctuation">(</span><span class="token number">260</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> sys.ps_thread_id(260) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 285 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/replication-configuration.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="replication-configuration">
</a>
19.1 Configuring Replication
</h2>
</div>
</div>
</div>
<div class="toc">
<dl class="toc">
<dt>
<span class="section">
<a href="binlog-replication-configuration-overview.html">
19.1.1 Binary Log File Position Based Replication Configuration Overview
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-howto.html">
19.1.2 Setting Up Binary Log File Position Based Replication
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-gtids.html">
19.1.3 Replication with Global Transaction Identifiers
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-mode-change-online.html">
19.1.4 Changing GTID Mode on Online Servers
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-multi-source.html">
19.1.5 MySQL Multi-Source Replication
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-options.html">
19.1.6 Replication and Binary Logging Options and Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="replication-administration.html">
19.1.7 Common Replication Administration Tasks
</a>
</span>
</dt>
</dl>
</div>
<p>
This section describes how to configure the different types of
replication available in MySQL and includes the setup and
configuration required for a replication environment, including
step-by-step instructions for creating a new replication
environment. The major components of this section are:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
For a guide to setting up two or more servers for replication
using binary log file positions,
<a class="xref" href="replication-howto.html" title="19.1.2 Setting Up Binary Log File Position Based Replication">
Section 19.1.2, “Setting Up Binary Log File Position Based Replication”
</a>
, deals with the
configuration of the servers and provides methods for copying
data between the source and replicas.
</p>
</li>
<li class="listitem">
<p>
For a guide to setting up two or more servers for replication
using GTID transactions,
<a class="xref" href="replication-gtids.html" title="19.1.3 Replication with Global Transaction Identifiers">
Section 19.1.3, “Replication with Global Transaction Identifiers”
</a>
,
deals with the configuration of the servers.
</p>
</li>
<li class="listitem">
<p>
Events in the binary log are recorded using a number of formats.
These are referred to as statement-based replication (SBR) or
row-based replication (RBR). A third type, mixed-format
replication (MIXED), uses SBR or RBR replication automatically
to take advantage of the benefits of both SBR and RBR formats
when appropriate. The different formats are discussed in
<a class="xref" href="replication-formats.html" title="19.2.1 Replication Formats">
Section 19.2.1, “Replication Formats”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Detailed information on the different configuration options and
variables that apply to replication is provided in
<a class="xref" href="replication-options.html" title="19.1.6 Replication and Binary Logging Options and Variables">
Section 19.1.6, “Replication and Binary Logging Options and Variables”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Once started, the replication process should require little
administration or monitoring. However, for advice on common
tasks that you may want to execute, see
<a class="xref" href="replication-administration.html" title="19.1.7 Common Replication Administration Tasks">
Section 19.1.7, “Common Replication Administration Tasks”
</a>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sys-processlist.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="sys-processlist">
</a>
30.4.3.22 The processlist and x$processlist Views
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045062686944">
</a>
<a class="indexterm" name="idm46045062685488">
</a>
<a class="indexterm" name="idm46045062684000">
</a>
<a class="indexterm" name="idm46045062682512">
</a>
<p>
The MySQL process list indicates the operations currently
being performed by the set of threads executing within the
server. The
<a class="link" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views">
<code class="literal">
processlist
</code>
</a>
and
<a class="link" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views">
<code class="literal">
x$processlist
</code>
</a>
views summarize
process information. They provide more complete information
than the
<a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement">
<code class="literal">
SHOW PROCESSLIST
</code>
</a>
statement and the
<code class="literal">
INFORMATION_SCHEMA
</code>
<a class="link" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table">
<code class="literal">
PROCESSLIST
</code>
</a>
table, and are also
nonblocking. By default, rows are sorted by descending process
time and descending wait time. For a comparison of process
information sources, see
<a class="xref" href="processlist-access.html#processlist-sources" title="Sources of Process Information">
Sources of Process Information
</a>
.
</p>
<p>
The column descriptions here are brief. For additional
information, see the description of the Performance Schema
<a class="link" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table">
<code class="literal">
threads
</code>
</a>
table at
<a class="xref" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table">
Section 29.12.22.8, “The threads Table”
</a>
.
</p>
<p>
The
<a class="link" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views">
<code class="literal">
processlist
</code>
</a>
and
<a class="link" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views">
<code class="literal">
x$processlist
</code>
</a>
views have these
columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
thd_id
</code>
</p>
<p>
The thread ID.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
conn_id
</code>
</p>
<p>
The connection ID.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
user
</code>
</p>
<p>
The thread user or thread name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
db
</code>
</p>
<p>
The default database for the thread, or
<code class="literal">
NULL
</code>
if there is none.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
command
</code>
</p>
<p>
For foreground threads, the type of command the thread is
executing on behalf of the client, or
<code class="literal">
Sleep
</code>
if the session is idle.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
state
</code>
</p>
<p>
An action, event, or state that indicates what the thread
is doing.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
time
</code>
</p>
<p>
The time in seconds that the thread has been in its
current state.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
current_statement
</code>
</p>
<p>
The statement the thread is executing, or
<code class="literal">
NULL
</code>
if it is not executing any
statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
execution_engine
</code>
</p>
<p>
The query execution engine. The value is either
<code class="literal">
PRIMARY
</code>
or
<code class="literal">
SECONDARY
</code>
. For use with HeatWave Service and
HeatWave, where the
<code class="literal">
PRIMARY
</code>
engine is
<code class="literal">
InnoDB
</code>
and
<code class="literal">
SECONDARY
</code>
engine is HeatWave (
<code class="literal">
RAPID
</code>
). For MySQL Community Edition
Server, MySQL Enterprise Edition Server (on-premise), and HeatWave Service without
HeatWave, the value is always
<code class="literal">
PRIMARY
</code>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
statement_latency
</code>
</p>
<p>
How long the statement has been executing.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
progress
</code>
</p>
<p>
The percentage of work completed for stages that support
progress reporting. See
<a class="xref" href="sys-schema-progress-reporting.html" title="30.3 sys Schema Progress Reporting">
Section 30.3, “sys Schema Progress Reporting”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
lock_latency
</code>
</p>
<p>
The time spent waiting for locks by the current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
cpu_latency
</code>
</p>
<p>
The time spent on CPU for the current thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
rows_examined
</code>
</p>
<p>
The number of rows read from storage engines by the
current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
rows_sent
</code>
</p>
<p>
The number of rows returned by the current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
rows_affected
</code>
</p>
<p>
The number of rows affected by the current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
tmp_tables
</code>
</p>
<p>
The number of internal in-memory temporary tables created
by the current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
tmp_disk_tables
</code>
</p>
<p>
The number of internal on-disk temporary tables created by
the current statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
full_scan
</code>
</p>
<p>
The number of full table scans performed by the current
statement.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
last_statement
</code>
</p>
<p>
The last statement executed by the thread, if there is no
currently executing statement or wait.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
last_statement_latency
</code>
</p>
<p>
How long the last statement executed.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
current_memory
</code>
</p>
<p>
The number of bytes allocated by the thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
last_wait
</code>
</p>
<p>
The name of the most recent wait event for the thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
last_wait_latency
</code>
</p>
<p>
The wait time of the most recent wait event for the
thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
source
</code>
</p>
<p>
The source file and line number containing the
instrumented code that produced the event.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
trx_latency
</code>
</p>
<p>
The wait time of the current transaction for the thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
trx_state
</code>
</p>
<p>
The state for the current transaction for the thread.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
trx_autocommit
</code>
</p>
<p>
Whether autocommit mode was enabled when the current
transaction started.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
pid
</code>
</p>
<p>
The client process ID.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
program_name
</code>
</p>
<p>
The client program name.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/innodb-autocommit-commit-rollback.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="innodb-autocommit-commit-rollback">
</a>
17.7.2.2 autocommit, Commit, and Rollback
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045164266752">
</a>
<a class="indexterm" name="idm46045164265360">
</a>
<p>
In
<code class="literal">
InnoDB
</code>
, all user activity occurs inside a
transaction. If
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
mode
is enabled, each SQL statement forms a single transaction on its
own. By default, MySQL starts the session for each new
connection with
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
enabled, so MySQL does a commit after each SQL statement if that
statement did not return an error. If a statement returns an
error, the commit or rollback behavior depends on the error. See
<a class="xref" href="innodb-error-handling.html" title="17.20.5 InnoDB Error Handling">
Section 17.20.5, “InnoDB Error Handling”
</a>
.
</p>
<p>
A session that has
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
enabled can perform a multiple-statement transaction by starting
it with an explicit
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
START
TRANSACTION
</code>
</a>
or
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
BEGIN
</code>
</a>
statement and ending it with a
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
or
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement. See
<a class="xref" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
Section 15.3.1, “START TRANSACTION, COMMIT, and ROLLBACK Statements”
</a>
.
</p>
<p>
If
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
mode is disabled
within a session with
<code class="literal">
SET autocommit = 0
</code>
, the
session always has a transaction open. A
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
or
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement ends the current transaction and a new one starts.
</p>
<p>
If a session that has
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
disabled ends
without explicitly committing the final transaction, MySQL rolls
back that transaction.
</p>
<p>
Some statements implicitly end a transaction, as if you had done
a
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
before executing the
statement. For details, see
<a class="xref" href="implicit-commit.html" title="15.3.3 Statements That Cause an Implicit Commit">
Section 15.3.3, “Statements That Cause an Implicit Commit”
</a>
.
</p>
<p>
A
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
means that the changes
made in the current transaction are made permanent and become
visible to other sessions. A
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement, on the other hand, cancels all modifications made by
the current transaction. Both
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
and
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
release all
<code class="literal">
InnoDB
</code>
locks that were set during
the current transaction.
</p>
<div class="simplesect">
<div class="titlepage">
<div>
<div class="simple">
<h5 class="title">
<a name="innodb-transactions-with-different-apis">
</a>
Grouping DML Operations with Transactions
</h5>
</div>
</div>
</div>
<a class="indexterm" name="idm46045164238512">
</a>
<p>
By default, connection to the MySQL server begins with
<a class="link" href="glossary.html#glos_autocommit" title="autocommit">
autocommit
</a>
mode
enabled, which automatically commits every SQL statement as
you execute it. This mode of operation might be unfamiliar if
you have experience with other database systems, where it is
standard practice to issue a sequence of
<a class="link" href="glossary.html#glos_dml" title="DML">
DML
</a>
statements and commit them
or roll them back all together.
</p>
<p>
To use multiple-statement
<a class="link" href="glossary.html#glos_transaction" title="transaction">
transactions
</a>
, switch
autocommit off with the SQL statement
<code class="literal">
SET autocommit
= 0
</code>
and end each transaction with
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
or
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
as
appropriate. To leave autocommit on, begin each transaction
with
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
START
TRANSACTION
</code>
</a>
and end it with
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
or
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
.
The following example shows two transactions. The first is
committed; the second is rolled back.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa16846410"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> test</code></pre>
</div>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67721008"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> customer <span class="token punctuation">(</span>a <span class="token datatype">INT</span><span class="token punctuation">,</span> b <span class="token datatype">CHAR</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">INDEX</span> <span class="token punctuation">(</span>a<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token comment" spellcheck="true">-- Do a transaction with autocommit turned on.</span>
<span class="token prompt">mysql></span> <span class="token keyword">START</span> <span class="token keyword">TRANSACTION</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> customer <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token string">'Heikki'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">COMMIT</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token comment" spellcheck="true">-- Do another transaction with autocommit turned off.</span>
<span class="token prompt">mysql></span> <span class="token keyword">SET</span> autocommit<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> customer <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">15</span><span class="token punctuation">,</span> <span class="token string">'John'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> customer <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">,</span> <span class="token string">'Paul'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">DELETE</span> <span class="token keyword">FROM</span> customer <span class="token keyword">WHERE</span> b <span class="token operator">=</span> <span class="token string">'Heikki'</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 1 row affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token comment" spellcheck="true">-- Now we undo those last 2 inserts and the delete.</span>
<span class="token prompt">mysql></span> <span class="token keyword">ROLLBACK</span><span class="token punctuation">;</span>
<span class="token output">Query OK, 0 rows affected (0.00 sec)</span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> customer<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> Heikki <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output">1 row in set (0.00 sec)</span>
<span class="token prompt">mysql></span></code></pre>
</div>
<h6>
<a name="idm46045164213216">
</a>
Transactions in Client-Side Languages
</h6>
<p>
In APIs such as PHP, Perl DBI, JDBC, ODBC, or the standard C
call interface of MySQL, you can send transaction control
statements such as
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
to
the MySQL server as strings just like any other SQL statements
such as
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
or
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
. Some APIs also offer
separate special transaction commit and rollback functions or
methods.
</p>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/sys-schema-redundant-indexes.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="sys-schema-redundant-indexes">
</a>
30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045062502672">
</a>
<a class="indexterm" name="idm46045062501216">
</a>
<a class="indexterm" name="idm46045062499712">
</a>
<a class="indexterm" name="idm46045062498208">
</a>
<p>
The
<a class="link" href="sys-schema-redundant-indexes.html" title="30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views">
<code class="literal">
schema_redundant_indexes
</code>
</a>
view displays indexes that duplicate other indexes or are made
redundant by them. The
<a class="link" href="sys-schema-redundant-indexes.html" title="30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views">
<code class="literal">
x$schema_flattened_keys
</code>
</a>
view is a helper view for
<a class="link" href="sys-schema-redundant-indexes.html" title="30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views">
<code class="literal">
schema_redundant_indexes
</code>
</a>
.
</p>
<p>
In the following column descriptions, the dominant index is
the one that makes the redundant index redundant.
</p>
<p>
The
<a class="link" href="sys-schema-redundant-indexes.html" title="30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views">
<code class="literal">
schema_redundant_indexes
</code>
</a>
view has these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
table_schema
</code>
</p>
<p>
The schema that contains the table.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
table_name
</code>
</p>
<p>
The table that contains the index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redundant_index_name
</code>
</p>
<p>
The name of the redundant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redundant_index_columns
</code>
</p>
<p>
The names of the columns in the redundant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
redundant_index_non_unique
</code>
</p>
<p>
The number of nonunique columns in the redundant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
dominant_index_name
</code>
</p>
<p>
The name of the dominant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
dominant_index_columns
</code>
</p>
<p>
The names of the columns in the dominant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
dominant_index_non_unique
</code>
</p>
<p>
The number of nonunique columns in the dominant index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
subpart_exists
</code>
</p>
<p>
Whether the index indexes only part of a column.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
sql_drop_index
</code>
</p>
<p>
The statement to execute to drop the redundant index.
</p>
</li>
</ul>
</div>
<p>
The
<a class="link" href="sys-schema-redundant-indexes.html" title="30.4.3.27 The schema_redundant_indexes and x$schema_flattened_keys Views">
<code class="literal">
x$schema_flattened_keys
</code>
</a>
view has these columns:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<code class="literal">
table_schema
</code>
</p>
<p>
The schema that contains the table.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
table_name
</code>
</p>
<p>
The table that contains the index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
index_name
</code>
</p>
<p>
An index name.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
non_unique
</code>
</p>
<p>
The number of nonunique columns in the index.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
subpart_exists
</code>
</p>
<p>
Whether the index indexes only part of a column.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
index_columns
</code>
</p>
<p>
The name of the columns in the index.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/security-guidelines.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h3 class="title">
<a name="security-guidelines">
</a>
8.1.1 Security Guidelines
</h3>
</div>
</div>
</div>
<a class="indexterm" name="idm46045252947168">
</a>
<a class="indexterm" name="idm46045252946096">
</a>
<p>
Anyone using MySQL on a computer connected to the Internet should
read this section to avoid the most common security mistakes.
</p>
<p>
In discussing security, it is necessary to consider fully
protecting the entire server host (not just the MySQL server)
against all types of applicable attacks: eavesdropping, altering,
playback, and denial of service. We do not cover all aspects of
availability and fault tolerance here.
</p>
<p>
MySQL uses security based on Access Control Lists (ACLs) for all
connections, queries, and other operations that users can attempt
to perform. There is also support for SSL-encrypted connections
between MySQL clients and servers. Many of the concepts discussed
here are not specific to MySQL at all; the same general ideas
apply to almost all applications.
</p>
<p>
When running MySQL, follow these guidelines:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="bold">
<strong>
Do not ever give anyone (except MySQL
<code class="literal">
root
</code>
accounts) access to the
<code class="literal">
user
</code>
table in the
<code class="literal">
mysql
</code>
system database!
</strong>
</span>
This is critical.
</p>
</li>
<li class="listitem">
<p>
Learn how the MySQL access privilege system works (see
<a class="xref" href="access-control.html" title="8.2 Access Control and Account Management">
Section 8.2, “Access Control and Account Management”
</a>
). Use the
<a class="link" href="grant.html" title="15.7.1.6 GRANT Statement">
<code class="literal">
GRANT
</code>
</a>
and
<a class="link" href="revoke.html" title="15.7.1.8 REVOKE Statement">
<code class="literal">
REVOKE
</code>
</a>
statements to control
access to MySQL. Do not grant more privileges than necessary.
Never grant privileges to all hosts.
</p>
<p>
Checklist:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Try
<code class="literal">
mysql -u root
</code>
. If you are able to
connect successfully to the server without being asked for
a password, anyone can connect to your MySQL server as the
MySQL
<code class="literal">
root
</code>
user with full privileges!
Review the MySQL installation instructions, paying
particular attention to the information about setting a
<code class="literal">
root
</code>
password. See
<a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account">
Section 2.9.4, “Securing the Initial MySQL Account”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Use the
<a class="link" href="show-grants.html" title="15.7.7.22 SHOW GRANTS Statement">
<code class="literal">
SHOW GRANTS
</code>
</a>
statement to check which accounts have access to what.
Then use the
<a class="link" href="revoke.html" title="15.7.1.8 REVOKE Statement">
<code class="literal">
REVOKE
</code>
</a>
statement to remove those privileges that are not
necessary.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Do not store cleartext passwords in your database. If your
computer becomes compromised, the intruder can take the full
list of passwords and use them. Instead, use
<a class="link" href="encryption-functions.html#function_sha2">
<code class="literal">
SHA2()
</code>
</a>
or some other one-way
hashing function and store the hash value.
</p>
<p>
To prevent password recovery using rainbow tables, do not use
these functions on a plain password; instead, choose some
string to be used as a salt, and use hash(hash(password)+salt)
values.
</p>
</li>
<li class="listitem">
<p>
Assume that all passwords will be subject to automated
cracking attempts using lists of known passwords, and also to
targeted guessing using publicly available information about
you, such as social media posts. Do not choose passwords that
consist of easily cracked or guessed items such as a
dictionary word, proper name, sports team name, acronym, or
commonly known phrase, particularly if they are relevant to
you. The use of upper case letters, number substitutions and
additions, and special characters does not help if these are
used in predictable ways. Also do not choose any password you
have seen used as an example anywhere, or a variation on it,
even if it was presented as an example of a strong password.
</p>
<p>
Instead, choose passwords that are as long and as
unpredictable as possible. That does not mean the combination
needs to be a random string of characters that is difficult to
remember and reproduce, although this is a good approach if
you have, for example, password manager software that can
generate and fill such passwords and store them securely. A
passphrase containing multiple words is easy to create,
remember, and reproduce, and is much more secure than a
typical user-selected password consisting of a single modified
word or a predictable sequence of characters. To create a
secure passphrase, ensure that the words and other items in it
are not a known phrase or quotation, do not occur in a
predictable order, and preferably have no previous
relationship to each other at all.
</p>
</li>
<li class="listitem">
<p>
Invest in a firewall. This protects you from at least 50% of
all types of exploits in any software. Put MySQL behind the
firewall or in a demilitarized zone (DMZ).
</p>
<p>
Checklist:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
Try to scan your ports from the Internet using a tool such
as
<code class="literal">
nmap
</code>
. MySQL uses port 3306 by
default. This port should not be accessible from untrusted
hosts. As a simple way to check whether your MySQL port is
open, try the following command from some remote machine,
where
<em class="replaceable">
<code>
server_host
</code>
</em>
is the host
name or IP address of the host on which your MySQL server
runs:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa24074555"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">telnet</span> <em class="replaceable">server_host</em> 3306</code></pre>
</div>
<p>
If
<span class="command">
<strong>
telnet
</strong>
</span>
hangs or the connection is
refused, the port is blocked, which is how you want it to
be. If you get a connection and some garbage characters,
the port is open, and should be closed on your firewall or
router, unless you really have a good reason to keep it
open.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
Applications that access MySQL should not trust any data
entered by users, and should be written using proper defensive
programming techniques. See
<a class="xref" href="secure-client-programming.html" title="8.1.7 Client Programming Security Guidelines">
Section 8.1.7, “Client Programming Security Guidelines”
</a>
.
</p>
</li>
<li class="listitem">
<p>
Do not transmit plain (unencrypted) data over the Internet.
This information is accessible to everyone who has the time
and ability to intercept it and use it for their own purposes.
Instead, use an encrypted protocol such as SSL or SSH. MySQL
supports internal SSL connections. Another technique is to use
SSH port-forwarding to create an encrypted (and compressed)
tunnel for the communication.
</p>
</li>
<li class="listitem">
<p>
Learn to use the
<span class="command">
<strong>
tcpdump
</strong>
</span>
and
<span class="command">
<strong>
strings
</strong>
</span>
utilities. In most cases, you can
check whether MySQL data streams are unencrypted by issuing a
command like the following:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa30405908"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">tcpdump</span> <span class="token property">-l</span> <span class="token property">-i</span> eth0 <span class="token property">-w</span> - src or dst port 3306 | strings</code></pre>
</div>
<p>
This works under Linux and should work with small
modifications under other systems.
</p>
<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Warning
</div>
<p>
If you do not see cleartext data, this does not always mean
that the information actually is encrypted. If you need high
security, consult with a security expert.
</p>
</div>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-enterprise-firewall.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="mysql-enterprise-firewall">
</a>
32.5 MySQL Enterprise Firewall Overview
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045060206816">
</a>
<a class="indexterm" name="idm46045060205728">
</a>
<p>
MySQL Enterprise Edition includes MySQL Enterprise Firewall, an application-level firewall that enables
database administrators to permit or deny SQL statement execution
based on matching against allowlists of accepted statement
patterns. This helps harden MySQL Server against attacks such as
SQL injection or attempts to exploit applications by using them
outside of their legitimate query workload characteristics.
</p>
<p>
Each MySQL account registered with the firewall has its own
statement allowlist, enabling protection to be tailored per
account. For a given account, the firewall can operate in
recording or protecting mode, for training in the accepted
statement patterns or protection against unacceptable statements.
</p>
<p>
For more information, see
<a class="xref" href="firewall.html" title="8.4.7 MySQL Enterprise Firewall">
Section 8.4.7, “MySQL Enterprise Firewall”
</a>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/language-structure.html | <div id="docs-body">
<div class="chapter">
<div class="titlepage">
<div>
<div>
<h1 class="title">
<a name="language-structure">
</a>
Chapter 11 Language Structure
</h1>
</div>
</div>
</div>
<div class="toc">
<p>
<b>
Table of Contents
</b>
</p>
<dl class="toc">
<dt>
<span class="section">
<a href="literals.html">
11.1 Literal Values
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="string-literals.html">
11.1.1 String Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="number-literals.html">
11.1.2 Numeric Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="date-and-time-literals.html">
11.1.3 Date and Time Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="hexadecimal-literals.html">
11.1.4 Hexadecimal Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="bit-value-literals.html">
11.1.5 Bit-Value Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="boolean-literals.html">
11.1.6 Boolean Literals
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="null-values.html">
11.1.7 NULL Values
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="identifiers.html">
11.2 Schema Object Names
</a>
</span>
</dt>
<dd>
<dl>
<dt>
<span class="section">
<a href="identifier-length.html">
11.2.1 Identifier Length Limits
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="identifier-qualifiers.html">
11.2.2 Identifier Qualifiers
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="identifier-case-sensitivity.html">
11.2.3 Identifier Case Sensitivity
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="identifier-mapping.html">
11.2.4 Mapping of Identifiers to File Names
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="function-resolution.html">
11.2.5 Function Name Parsing and Resolution
</a>
</span>
</dt>
</dl>
</dd>
<dt>
<span class="section">
<a href="keywords.html">
11.3 Keywords and Reserved Words
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="user-variables.html">
11.4 User-Defined Variables
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="expressions.html">
11.5 Expressions
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="query-attributes.html">
11.6 Query Attributes
</a>
</span>
</dt>
<dt>
<span class="section">
<a href="comments.html">
11.7 Comments
</a>
</span>
</dt>
</dl>
</div>
<p>
This chapter discusses the rules for writing the following elements
of
<a class="link" href="glossary.html#glos_sql" title="SQL">
SQL
</a>
statements when using MySQL:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Literal values such as strings and numbers
</p>
</li>
<li class="listitem">
<p>
Identifiers such as database, table, and column names
</p>
</li>
<li class="listitem">
<p>
Keywords and reserved words
</p>
</li>
<li class="listitem">
<p>
User-defined and system variables
</p>
</li>
<li class="listitem">
<p>
Expressions
</p>
</li>
<li class="listitem">
<p>
Query attributes
</p>
</li>
<li class="listitem">
<p>
Comments
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-acid.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h2 class="title">
<a name="mysql-acid">
</a>
17.2 InnoDB and the ACID Model
</h2>
</div>
</div>
</div>
<a class="indexterm" name="idm46045167296288">
</a>
<p>
The
<a class="link" href="glossary.html#glos_acid" title="ACID">
ACID
</a>
model is a set of database
design principles that emphasize aspects of reliability that are
important for business data and mission-critical applications. MySQL
includes components such as the
<code class="literal">
InnoDB
</code>
storage
engine that adhere closely to the ACID model so that data is not
corrupted and results are not distorted by exceptional conditions
such as software crashes and hardware malfunctions. When you rely on
ACID-compliant features, you do not need to reinvent the wheel of
consistency checking and crash recovery mechanisms. In cases where
you have additional software safeguards, ultra-reliable hardware, or
an application that can tolerate a small amount of data loss or
inconsistency, you can adjust MySQL settings to trade some of the
ACID reliability for greater performance or throughput.
</p>
<p>
The following sections discuss how MySQL features, in particular the
<code class="literal">
InnoDB
</code>
storage engine, interact with the
categories of the ACID model:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<span class="bold">
<strong>
A
</strong>
</span>
: atomicity.
</p>
</li>
<li class="listitem">
<p>
<span class="bold">
<strong>
C
</strong>
</span>
: consistency.
</p>
</li>
<li class="listitem">
<p>
<span class="bold">
<strong>
I:
</strong>
</span>
: isolation.
</p>
</li>
<li class="listitem">
<p>
<span class="bold">
<strong>
D
</strong>
</span>
: durability.
</p>
</li>
</ul>
</div>
<h3>
<a name="idm46045167284784">
</a>
Atomicity
</h3>
<p>
The
<span class="bold">
<strong>
atomicity
</strong>
</span>
aspect of the ACID
model mainly involves
<code class="literal">
InnoDB
</code>
<a class="link" href="glossary.html#glos_transaction" title="transaction">
transactions
</a>
. Related MySQL
features include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
setting.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
COMMIT
</code>
</a>
statement.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="commit.html" title="15.3.1 START TRANSACTION, COMMIT, and ROLLBACK Statements">
<code class="literal">
ROLLBACK
</code>
</a>
statement.
</p>
</li>
</ul>
</div>
<h3>
<a name="idm46045167274880">
</a>
Consistency
</h3>
<p>
The
<span class="bold">
<strong>
consistency
</strong>
</span>
aspect of the ACID
model mainly involves internal
<code class="literal">
InnoDB
</code>
processing
to protect data from crashes. Related MySQL features include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<code class="literal">
InnoDB
</code>
doublewrite buffer. See
<a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer">
Section 17.6.4, “Doublewrite Buffer”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
InnoDB
</code>
crash recovery. See
<a class="xref" href="innodb-recovery.html#innodb-crash-recovery" title="InnoDB Crash Recovery">
InnoDB Crash Recovery
</a>
.
</p>
</li>
</ul>
</div>
<h3>
<a name="idm46045167267264">
</a>
Isolation
</h3>
<p>
The
<span class="bold">
<strong>
isolation
</strong>
</span>
aspect of the ACID
model mainly involves
<code class="literal">
InnoDB
</code>
<a class="link" href="glossary.html#glos_transaction" title="transaction">
transactions
</a>
, in particular
the
<a class="link" href="glossary.html#glos_isolation_level" title="isolation level">
isolation level
</a>
that
applies to each transaction. Related MySQL features include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<a class="link" href="server-system-variables.html#sysvar_autocommit">
<code class="literal">
autocommit
</code>
</a>
setting.
</p>
</li>
<li class="listitem">
<p>
Transaction isolation levels and the
<a class="link" href="set-transaction.html" title="15.3.7 SET TRANSACTION Statement">
<code class="literal">
SET
TRANSACTION
</code>
</a>
statement. See
<a class="xref" href="innodb-transaction-isolation-levels.html" title="17.7.2.1 Transaction Isolation Levels">
Section 17.7.2.1, “Transaction Isolation Levels”
</a>
.
</p>
</li>
<li class="listitem">
<p>
The low-level details of
<code class="literal">
InnoDB
</code>
<a class="link" href="glossary.html#glos_locking" title="locking">
locking
</a>
. Details can be
viewed in the
<code class="literal">
INFORMATION_SCHEMA
</code>
tables (see
<a class="xref" href="innodb-information-schema-transactions.html" title="17.15.2 InnoDB INFORMATION_SCHEMA Transaction and Locking Information">
Section 17.15.2, “InnoDB INFORMATION_SCHEMA Transaction and Locking Information”
</a>
) and
Performance Schema
<a class="link" href="performance-schema-data-locks-table.html" title="29.12.13.1 The data_locks Table">
<code class="literal">
data_locks
</code>
</a>
and
<a class="link" href="performance-schema-data-lock-waits-table.html" title="29.12.13.2 The data_lock_waits Table">
<code class="literal">
data_lock_waits
</code>
</a>
tables.
</p>
</li>
</ul>
</div>
<h3>
<a name="idm46045167250896">
</a>
Durability
</h3>
<p>
The
<span class="bold">
<strong>
durability
</strong>
</span>
aspect of the ACID
model involves MySQL software features interacting with your
particular hardware configuration. Because of the many possibilities
depending on the capabilities of your CPU, network, and storage
devices, this aspect is the most complicated to provide concrete
guidelines for. (And those guidelines might take the form of
<span class="quote">
“
<span class="quote">
buy new hardware
</span>
”
</span>
.) Related MySQL features include:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The
<code class="literal">
InnoDB
</code>
doublewrite buffer. See
<a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer">
Section 17.6.4, “Doublewrite Buffer”
</a>
.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit">
<code class="literal">
innodb_flush_log_at_trx_commit
</code>
</a>
variable.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="replication-options-binary-log.html#sysvar_sync_binlog">
<code class="literal">
sync_binlog
</code>
</a>
variable.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table">
<code class="literal">
innodb_file_per_table
</code>
</a>
variable.
</p>
</li>
<li class="listitem">
<p>
The write buffer in a storage device, such as a disk drive, SSD,
or RAID array.
</p>
</li>
<li class="listitem">
<p>
A battery-backed cache in a storage device.
</p>
</li>
<li class="listitem">
<p>
The operating system used to run MySQL, in particular its
support for the
<code class="literal">
fsync()
</code>
system call.
</p>
</li>
<li class="listitem">
<p>
An uninterruptible power supply (UPS) protecting the electrical
power to all computer servers and storage devices that run MySQL
servers and store MySQL data.
</p>
</li>
<li class="listitem">
<p>
Your backup strategy, such as frequency and types of backups,
and backup retention periods.
</p>
</li>
<li class="listitem">
<p>
For distributed or hosted data applications, the particular
characteristics of the data centers where the hardware for the
MySQL servers is located, and network connections between the
data centers.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/function-optimization.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="function-optimization">
</a>
10.2.1.20 Function Call Optimization
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045228576160">
</a>
<a class="indexterm" name="idm46045228574688">
</a>
<a class="indexterm" name="idm46045228573184">
</a>
<a class="indexterm" name="idm46045228571680">
</a>
<p>
MySQL functions are tagged internally as deterministic or
nondeterministic. A function is nondeterministic if, given
fixed values for its arguments, it can return different
results for different invocations. Examples of
nondeterministic functions:
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
,
<a class="link" href="miscellaneous-functions.html#function_uuid">
<code class="literal">
UUID()
</code>
</a>
.
</p>
<p>
If a function is tagged nondeterministic, a reference to it in
a
<code class="literal">
WHERE
</code>
clause is evaluated for every row
(when selecting from one table) or combination of rows (when
selecting from a multiple-table join).
</p>
<p>
MySQL also determines when to evaluate functions based on
types of arguments, whether the arguments are table columns or
constant values. A deterministic function that takes a table
column as argument must be evaluated whenever that column
changes value.
</p>
<p>
Nondeterministic functions may affect query performance. For
example, some optimizations may not be available, or more
locking might be required. The following discussion uses
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
but applies to other
nondeterministic functions as well.
</p>
<p>
Suppose that a table
<code class="literal">
t
</code>
has this definition:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa49956727"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t <span class="token punctuation">(</span>id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">,</span> col_a <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">100</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Consider these two queries:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa68297795"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t <span class="token keyword">WHERE</span> id <span class="token operator">=</span> <span class="token function">POW</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t <span class="token keyword">WHERE</span> id <span class="token operator">=</span> <span class="token function">FLOOR</span><span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">+</span> <span class="token function">RAND</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">49</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Both queries appear to use a primary key lookup because of the
equality comparison against the primary key, but that is true
only for the first of them:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
The first query always produces a maximum of one row
because
<a class="link" href="mathematical-functions.html#function_pow">
<code class="literal">
POW()
</code>
</a>
with constant
arguments is a constant value and is used for index
lookup.
</p>
</li>
<li class="listitem">
<p>
The second query contains an expression that uses the
nondeterministic function
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
, which is not
constant in the query but in fact has a new value for
every row of table
<code class="literal">
t
</code>
. Consequently, the
query reads every row of the table, evaluates the
predicate for each row, and outputs all rows for which the
primary key matches the random value. This might be zero,
one, or multiple rows, depending on the
<code class="literal">
id
</code>
column values and the values in the
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
sequence.
</p>
</li>
</ul>
</div>
<p>
The effects of nondeterminism are not limited to
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements. This
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
statement uses a
nondeterministic function to select rows to be modified:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa58408610"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> t <span class="token keyword">SET</span> col_a <span class="token operator">=</span> <em class="replaceable">some_expr</em> <span class="token keyword">WHERE</span> id <span class="token operator">=</span> <span class="token function">FLOOR</span><span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">+</span> <span class="token function">RAND</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">49</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
Presumably the intent is to update at most a single row for
which the primary key matches the expression. However, it
might update zero, one, or multiple rows, depending on the
<code class="literal">
id
</code>
column values and the values in the
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
sequence.
</p>
<p>
The behavior just described has implications for performance
and replication:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Because a nondeterministic function does not produce a
constant value, the optimizer cannot use strategies that
might otherwise be applicable, such as index lookups. The
result may be a table scan.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
InnoDB
</code>
might escalate to a range-key
lock rather than taking a single row lock for one matching
row.
</p>
</li>
<li class="listitem">
<p>
Updates that do not execute deterministically are unsafe
for replication.
</p>
</li>
</ul>
</div>
<p>
The difficulties stem from the fact that the
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
function is evaluated
once for every row of the table. To avoid multiple function
evaluations, use one of these techniques:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Move the expression containing the nondeterministic
function to a separate statement, saving the value in a
variable. In the original statement, replace the
expression with a reference to the variable, which the
optimizer can treat as a constant value:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28816932"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@keyval</span> <span class="token operator">=</span> <span class="token function">FLOOR</span><span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">+</span> <span class="token function">RAND</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">49</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">UPDATE</span> t <span class="token keyword">SET</span> col_a <span class="token operator">=</span> <em class="replaceable">some_expr</em> <span class="token keyword">WHERE</span> id <span class="token operator">=</span> <span class="token variable">@keyval</span><span class="token punctuation">;</span></code></pre>
</div>
</li>
<li class="listitem">
<p>
Assign the random value to a variable in a derived table.
This technique causes the variable to be assigned a value,
once, prior to its use in the comparison in the
<code class="literal">
WHERE
</code>
clause:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46802398"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> <span class="token comment" spellcheck="true">/*+ NO_MERGE(dt) */</span> t<span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token function">FLOOR</span><span class="token punctuation">(</span><span class="token number">1</span> <span class="token operator">+</span> <span class="token function">RAND</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">*</span> <span class="token number">49</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> r<span class="token punctuation">)</span> <span class="token keyword">AS</span> dt
<span class="token keyword">SET</span> col_a <span class="token operator">=</span> <em class="replaceable">some_expr</em> <span class="token keyword">WHERE</span> id <span class="token operator">=</span> dt<span class="token punctuation">.</span>r<span class="token punctuation">;</span></code></pre>
</div>
</li>
</ul>
</div>
<p>
As mentioned previously, a nondeterministic expression in the
<code class="literal">
WHERE
</code>
clause might prevent optimizations
and result in a table scan. However, it may be possible to
partially optimize the
<code class="literal">
WHERE
</code>
clause if
other expressions are deterministic. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa29088753"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t <span class="token keyword">WHERE</span> partial_key<span class="token operator">=</span><span class="token number">5</span> <span class="token operator">AND</span> some_column<span class="token operator">=</span><span class="token function">RAND</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
If the optimizer can use
<code class="literal">
partial_key
</code>
to
reduce the set of rows selected,
<a class="link" href="mathematical-functions.html#function_rand">
<code class="literal">
RAND()
</code>
</a>
is executed fewer times,
which diminishes the effect of nondeterminism on optimization.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/nested-join-optimization.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="nested-join-optimization">
</a>
10.2.1.8 Nested Join Optimization
</h4>
</div>
</div>
</div>
<p>
The syntax for expressing joins permits nested joins. The
following discussion refers to the join syntax described in
<a class="xref" href="join.html" title="15.2.13.2 JOIN Clause">
Section 15.2.13.2, “JOIN Clause”
</a>
.
</p>
<p>
The syntax of
<em class="replaceable">
<code>
table_factor
</code>
</em>
is
extended in comparison with the SQL Standard. The latter
accepts only
<em class="replaceable">
<code>
table_reference
</code>
</em>
, not a
list of them inside a pair of parentheses. This is a
conservative extension if we consider each comma in a list of
<em class="replaceable">
<code>
table_reference
</code>
</em>
items as equivalent
to an inner join. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa87664950"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2<span class="token punctuation">,</span> t3<span class="token punctuation">,</span> t4<span class="token punctuation">)</span>
<span class="token keyword">ON</span> <span class="token punctuation">(</span>t2<span class="token punctuation">.</span>a<span class="token operator">=</span>t1<span class="token punctuation">.</span>a <span class="token operator">AND</span> t3<span class="token punctuation">.</span>b<span class="token operator">=</span>t1<span class="token punctuation">.</span>b <span class="token operator">AND</span> t4<span class="token punctuation">.</span>c<span class="token operator">=</span>t1<span class="token punctuation">.</span>c<span class="token punctuation">)</span></code></pre>
</div>
<p>
Is equivalent to:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa19116309"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2 <span class="token keyword">CROSS</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">CROSS</span> <span class="token keyword">JOIN</span> t4<span class="token punctuation">)</span>
<span class="token keyword">ON</span> <span class="token punctuation">(</span>t2<span class="token punctuation">.</span>a<span class="token operator">=</span>t1<span class="token punctuation">.</span>a <span class="token operator">AND</span> t3<span class="token punctuation">.</span>b<span class="token operator">=</span>t1<span class="token punctuation">.</span>b <span class="token operator">AND</span> t4<span class="token punctuation">.</span>c<span class="token operator">=</span>t1<span class="token punctuation">.</span>c<span class="token punctuation">)</span></code></pre>
</div>
<p>
In MySQL,
<code class="literal">
CROSS JOIN
</code>
is syntactically
equivalent to
<code class="literal">
INNER JOIN
</code>
; they can replace
each other. In standard SQL, they are not equivalent.
<code class="literal">
INNER JOIN
</code>
is used with an
<code class="literal">
ON
</code>
clause;
<code class="literal">
CROSS JOIN
</code>
is
used otherwise.
</p>
<p>
In general, parentheses can be ignored in join expressions
containing only inner join operations. Consider this join
expression:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa31032284"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b <span class="token operator">OR</span> t2<span class="token punctuation">.</span>b <span class="token operator">IS</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span>
<span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a</code></pre>
</div>
<p>
After removing parentheses and grouping operations to the
left, that join expression transforms into this expression:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35093906"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span>t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t2 <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">)</span> <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3
<span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b <span class="token operator">OR</span> t2<span class="token punctuation">.</span>b <span class="token operator">IS</span> <span class="token boolean">NULL</span></code></pre>
</div>
<p>
Yet, the two expressions are not equivalent. To see this,
suppose that the tables
<code class="literal">
t1
</code>
,
<code class="literal">
t2
</code>
, and
<code class="literal">
t3
</code>
have the
following state:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
Table
<code class="literal">
t1
</code>
contains rows
<code class="literal">
(1)
</code>
,
<code class="literal">
(2)
</code>
</p>
</li>
<li class="listitem">
<p>
Table
<code class="literal">
t2
</code>
contains row
<code class="literal">
(1,101)
</code>
</p>
</li>
<li class="listitem">
<p>
Table
<code class="literal">
t3
</code>
contains row
<code class="literal">
(101)
</code>
</p>
</li>
</ul>
</div>
<p>
In this case, the first expression returns a result set
including the rows
<code class="literal">
(1,1,101,101)
</code>
,
<code class="literal">
(2,NULL,NULL,NULL)
</code>
, whereas the second
expression returns the rows
<code class="literal">
(1,1,101,101)
</code>
,
<code class="literal">
(2,NULL,NULL,101)
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa58147795"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span>
<span class="token keyword">FROM</span> t1
<span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span>
<span class="token punctuation">(</span>t2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b <span class="token operator">OR</span> t2<span class="token punctuation">.</span>b <span class="token operator">IS</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span>
<span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span>
<span class="token keyword">FROM</span> <span class="token punctuation">(</span>t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t2 <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">)</span>
<span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3
<span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b <span class="token operator">OR</span> t2<span class="token punctuation">.</span>b <span class="token operator">IS</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
In the following example, an outer join operation is used
together with an inner join operation:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa39842864"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2<span class="token punctuation">,</span> t3<span class="token punctuation">)</span> <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a</code></pre>
</div>
<p>
That expression cannot be transformed into the following
expression:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa16303848"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t2 <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">,</span> t3</code></pre>
</div>
<p>
For the given table states, the two expressions return
different sets of rows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa58551561"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span>
<span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2<span class="token punctuation">,</span> t3<span class="token punctuation">)</span> <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span>
<span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t2 <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a<span class="token punctuation">,</span> t3<span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> 101 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
<p>
Therefore, if we omit parentheses in a join expression with
outer join operators, we might change the result set for the
original expression.
</p>
<p>
More exactly, we cannot ignore parentheses in the right
operand of the left outer join operation and in the left
operand of a right join operation. In other words, we cannot
ignore parentheses for the inner table expressions of outer
join operations. Parentheses for the other operand (operand
for the outer table) can be ignored.
</p>
<p>
The following expression:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa28040457"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> P<span class="token punctuation">(</span>t2<span class="token punctuation">.</span>b<span class="token punctuation">,</span>t3<span class="token punctuation">.</span>b<span class="token punctuation">)</span></code></pre>
</div>
<p>
Is equivalent to this expression for any tables
<code class="literal">
t1,t2,t3
</code>
and any condition
<code class="literal">
P
</code>
over attributes
<code class="literal">
t2.b
</code>
and
<code class="literal">
t3.b
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa21609699"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">t1<span class="token punctuation">,</span> t2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> P<span class="token punctuation">(</span>t2<span class="token punctuation">.</span>b<span class="token punctuation">,</span>t3<span class="token punctuation">.</span>b<span class="token punctuation">)</span></code></pre>
</div>
<p>
Whenever the order of execution of join operations in a join
expression (
<em class="replaceable">
<code>
joined_table
</code>
</em>
) is not
from left to right, we talk about nested joins. Consider the
following queries:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25748256"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b<span class="token punctuation">)</span> <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a
<span class="token keyword">WHERE</span> t1<span class="token punctuation">.</span>a <span class="token operator">></span> <span class="token number">1</span>
<span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>t2<span class="token punctuation">,</span> t3<span class="token punctuation">)</span> <span class="token keyword">ON</span> t1<span class="token punctuation">.</span>a<span class="token operator">=</span>t2<span class="token punctuation">.</span>a
<span class="token keyword">WHERE</span> <span class="token punctuation">(</span>t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b <span class="token operator">OR</span> t2<span class="token punctuation">.</span>b <span class="token operator">IS</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span> <span class="token operator">AND</span> t1<span class="token punctuation">.</span>a <span class="token operator">></span> <span class="token number">1</span></code></pre>
</div>
<p>
Those queries are considered to contain these nested joins:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa76005027"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">t2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> t3 <span class="token keyword">ON</span> t2<span class="token punctuation">.</span>b<span class="token operator">=</span>t3<span class="token punctuation">.</span>b
t2<span class="token punctuation">,</span> t3</code></pre>
</div>
<p>
In the first query, the nested join is formed with a left join
operation. In the second query, it is formed with an inner
join operation.
</p>
<p>
In the first query, the parentheses can be omitted: The
grammatical structure of the join expression dictates the same
order of execution for join operations. For the second query,
the parentheses cannot be omitted, although the join
expression here can be interpreted unambiguously without them.
In our extended syntax, the parentheses in
<code class="literal">
(t2,
t3)
</code>
of the second query are required, although
theoretically the query could be parsed without them: We still
would have unambiguous syntactical structure for the query
because
<code class="literal">
LEFT JOIN
</code>
and
<code class="literal">
ON
</code>
play the role of the left and right delimiters for the
expression
<code class="literal">
(t2,t3)
</code>
.
</p>
<p>
The preceding examples demonstrate these points:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
For join expressions involving only inner joins (and not
outer joins), parentheses can be removed and joins
evaluated left to right. In fact, tables can be evaluated
in any order.
</p>
</li>
<li class="listitem">
<p>
The same is not true, in general, for outer joins or for
outer joins mixed with inner joins. Removal of parentheses
may change the result.
</p>
</li>
</ul>
</div>
<a class="indexterm" name="idm46045229506896">
</a>
<a class="indexterm" name="idm46045229505408">
</a>
<p>
Queries with nested outer joins are executed in the same
pipeline manner as queries with inner joins. More exactly, a
variation of the nested-loop join algorithm is exploited.
Recall the algorithm by which the nested-loop join executes a
query (see
<a class="xref" href="nested-loop-joins.html" title="10.2.1.7 Nested-Loop Join Algorithms">
Section 10.2.1.7, “Nested-Loop Join Algorithms”
</a>
). Suppose that
a join query over 3 tables
<code class="literal">
T1,T2,T3
</code>
has
this form:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa70881656"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> T1 <span class="token keyword">INNER</span> <span class="token keyword">JOIN</span> T2 <span class="token keyword">ON</span> P1<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">)</span>
<span class="token keyword">INNER</span> <span class="token keyword">JOIN</span> T3 <span class="token keyword">ON</span> P2<span class="token punctuation">(</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span>
<span class="token keyword">WHERE</span> P<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span></code></pre>
</div>
<p>
Here,
<code class="literal">
P1(T1,T2)
</code>
and
<code class="literal">
P2(T3,T3)
</code>
are some join conditions (on
expressions), whereas
<code class="literal">
P(T1,T2,T3)
</code>
is a
condition over columns of tables
<code class="literal">
T1,T2,T3
</code>
.
</p>
<p>
The nested-loop join algorithm would execute this query in the
following manner:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa95642955"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 <span class="token punctuation">{</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t3 <span class="token keyword">in</span> T3 such that <span class="token function">P2</span><span class="token punctuation">(</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
The notation
<code class="literal">
t1||t2||t3
</code>
indicates a row
constructed by concatenating the columns of rows
<code class="literal">
t1
</code>
,
<code class="literal">
t2
</code>
, and
<code class="literal">
t3
</code>
. In some of the following examples,
<code class="literal">
NULL
</code>
where a table name appears means a row
in which
<code class="literal">
NULL
</code>
is used for each column of
that table. For example,
<code class="literal">
t1||t2||NULL
</code>
indicates a row constructed by concatenating the columns of
rows
<code class="literal">
t1
</code>
and
<code class="literal">
t2
</code>
, and
<code class="literal">
NULL
</code>
for each column of
<code class="literal">
t3
</code>
. Such a row is said to be
<code class="literal">
NULL
</code>
-complemented.
</p>
<a class="indexterm" name="idm46045229486992">
</a>
<p>
Now consider a query with nested outer joins:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa23053414"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> T1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span>
<span class="token punctuation">(</span>T2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> T3 <span class="token keyword">ON</span> P2<span class="token punctuation">(</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">ON</span> P1<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">)</span>
<span class="token keyword">WHERE</span> P<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span></code></pre>
</div>
<p>
For this query, modify the nested-loop pattern to obtain:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa41827055"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 <span class="token punctuation">{</span>
BOOL f1<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
BOOL f2<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t3 <span class="token keyword">in</span> T3 such that <span class="token function">P2</span><span class="token punctuation">(</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f2<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
f1<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f1<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f1<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>NULL<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>NULL<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
In general, for any nested loop for the first inner table in
an outer join operation, a flag is introduced that is turned
off before the loop and is checked after the loop. The flag is
turned on when for the current row from the outer table a
match from the table representing the inner operand is found.
If at the end of the loop cycle the flag is still off, no
match has been found for the current row of the outer table.
In this case, the row is complemented by
<code class="literal">
NULL
</code>
values for the columns of the inner
tables. The result row is passed to the final check for the
output or into the next nested loop, but only if the row
satisfies the join condition of all embedded outer joins.
</p>
<p>
In the example, the outer join table expressed by the
following expression is embedded:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa36860968"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span>T2 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> T3 <span class="token keyword">ON</span> P2<span class="token punctuation">(</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span><span class="token punctuation">)</span></code></pre>
</div>
<p>
For the query with inner joins, the optimizer could choose a
different order of nested loops, such as this one:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa30785924"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t3 <span class="token keyword">in</span> T3 <span class="token punctuation">{</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P2</span><span class="token punctuation">(</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t1 <span class="token keyword">in</span> T1 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
For queries with outer joins, the optimizer can choose only
such an order where loops for outer tables precede loops for
inner tables. Thus, for our query with outer joins, only one
nesting order is possible. For the following query, the
optimizer evaluates two different nestings. In both nestings,
<code class="literal">
T1
</code>
must be processed in the outer loop
because it is used in an outer join.
<code class="literal">
T2
</code>
and
<code class="literal">
T3
</code>
are used in an inner join, so that join
must be processed in the inner loop. However, because the join
is an inner join,
<code class="literal">
T2
</code>
and
<code class="literal">
T3
</code>
can be processed in either order.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa98447144"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> T1 <span class="token keyword">LEFT</span> <span class="token keyword">JOIN</span> <span class="token punctuation">(</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span> <span class="token keyword">ON</span> P1<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">)</span> <span class="token operator">AND</span> P2<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T3<span class="token punctuation">)</span>
<span class="token keyword">WHERE</span> P<span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span></code></pre>
</div>
<p>
One nesting evaluates
<code class="literal">
T2
</code>
, then
<code class="literal">
T3
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa6597944"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 <span class="token punctuation">{</span>
BOOL f1<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t3 <span class="token keyword">in</span> T3 such that <span class="token function">P2</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f1<span class="token punctuation">:</span><span class="token operator">=</span>TRUE
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f1<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>NULL<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>NULL<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
The other nesting evaluates
<code class="literal">
T3
</code>
, then
<code class="literal">
T2
</code>
:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa79320099"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 <span class="token punctuation">{</span>
BOOL f1<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t3 <span class="token keyword">in</span> T3 such that <span class="token function">P2</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f1<span class="token punctuation">:</span><span class="token operator">=</span>TRUE
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f1<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>NULL<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>NULL<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
When discussing the nested-loop algorithm for inner joins, we
omitted some details whose impact on the performance of query
execution may be huge. We did not mention so-called
<span class="quote">
“
<span class="quote">
pushed-down
</span>
”
</span>
conditions. Suppose that our
<code class="literal">
WHERE
</code>
condition
<code class="literal">
P(T1,T2,T3)
</code>
can be represented by a
conjunctive formula:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-clike"><div class="docs-select-all right" id="sa46103278"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike"><span class="token function">P</span><span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">,</span>T2<span class="token punctuation">)</span> <span class="token operator">=</span> <span class="token function">C1</span><span class="token punctuation">(</span>T1<span class="token punctuation">)</span> AND <span class="token function">C2</span><span class="token punctuation">(</span>T2<span class="token punctuation">)</span> AND <span class="token function">C3</span><span class="token punctuation">(</span>T3<span class="token punctuation">)</span><span class="token punctuation">.</span></code></pre>
</div>
<p>
In this case, MySQL actually uses the following nested-loop
algorithm for the execution of the query with inner joins:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa61551975"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 such that <span class="token function">C1</span><span class="token punctuation">(</span>t1<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t2 <span class="token keyword">in</span> T2 such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> AND <span class="token function">C2</span><span class="token punctuation">(</span>t2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
FOR each row t3 <span class="token keyword">in</span> T3 such that <span class="token function">P2</span><span class="token punctuation">(</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> AND <span class="token function">C3</span><span class="token punctuation">(</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
You see that each of the conjuncts
<code class="literal">
C1(T1)
</code>
,
<code class="literal">
C2(T2)
</code>
,
<code class="literal">
C3(T3)
</code>
are
pushed out of the most inner loop to the most outer loop where
it can be evaluated. If
<code class="literal">
C1(T1)
</code>
is a very
restrictive condition, this condition pushdown may greatly
reduce the number of rows from table
<code class="literal">
T1
</code>
passed to the inner loops. As a result, the execution time for
the query may improve immensely.
</p>
<p>
For a query with outer joins, the
<code class="literal">
WHERE
</code>
condition is to be checked only after it has been found that
the current row from the outer table has a match in the inner
tables. Thus, the optimization of pushing conditions out of
the inner nested loops cannot be applied directly to queries
with outer joins. Here we must introduce conditional
pushed-down predicates guarded by the flags that are turned on
when a match has been encountered.
</p>
<p>
Recall this example with outer joins:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-clike"><div class="docs-select-all right" id="sa75761356"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike"><span class="token function">P</span><span class="token punctuation">(</span>T1<span class="token punctuation">,</span>T2<span class="token punctuation">,</span>T3<span class="token punctuation">)</span><span class="token operator">=</span><span class="token function">C1</span><span class="token punctuation">(</span>T1<span class="token punctuation">)</span> AND <span class="token function">C</span><span class="token punctuation">(</span>T2<span class="token punctuation">)</span> AND <span class="token function">C3</span><span class="token punctuation">(</span>T3<span class="token punctuation">)</span></code></pre>
</div>
<p>
For that example, the nested-loop algorithm using guarded
pushed-down conditions looks like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-clike"><div class="docs-select-all right" id="sa94400307"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-clike">FOR each row t1 <span class="token keyword">in</span> T1 such that <span class="token function">C1</span><span class="token punctuation">(</span>t1<span class="token punctuation">)</span> <span class="token punctuation">{</span>
BOOL f1<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t2 <span class="token keyword">in</span> T2
such that <span class="token function">P1</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">)</span> AND <span class="token punctuation">(</span>f1<span class="token operator">?</span><span class="token function">C2</span><span class="token punctuation">(</span>t2<span class="token punctuation">)</span><span class="token punctuation">:</span>TRUE<span class="token punctuation">)</span> <span class="token punctuation">{</span>
BOOL f2<span class="token punctuation">:</span><span class="token operator">=</span>FALSE<span class="token punctuation">;</span>
FOR each row t3 <span class="token keyword">in</span> T3
such that <span class="token function">P2</span><span class="token punctuation">(</span>t2<span class="token punctuation">,</span>t3<span class="token punctuation">)</span> AND <span class="token punctuation">(</span>f1<span class="token operator">&&</span>f2<span class="token operator">?</span><span class="token function">C3</span><span class="token punctuation">(</span>t3<span class="token punctuation">)</span><span class="token punctuation">:</span>TRUE<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token punctuation">(</span>f1<span class="token operator">&&</span>f2<span class="token operator">?</span>TRUE<span class="token punctuation">:</span><span class="token punctuation">(</span><span class="token function">C2</span><span class="token punctuation">(</span>t2<span class="token punctuation">)</span> AND <span class="token function">C3</span><span class="token punctuation">(</span>t3<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>t3<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f2<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
f1<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f2<span class="token punctuation">)</span> <span class="token punctuation">{</span>
IF <span class="token punctuation">(</span>f1<span class="token operator">?</span>TRUE<span class="token punctuation">:</span><span class="token function">C2</span><span class="token punctuation">(</span>t2<span class="token punctuation">)</span> <span class="token operator">&&</span> <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>t2<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>t2<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
f1<span class="token operator">=</span>TRUE<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
IF <span class="token punctuation">(</span><span class="token operator">!</span>f1 <span class="token operator">&&</span> <span class="token function">P</span><span class="token punctuation">(</span>t1<span class="token punctuation">,</span>NULL<span class="token punctuation">,</span>NULL<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">:</span><span class="token operator">=</span>t1<span class="token operator">||</span>NULL<span class="token operator">||</span>NULL<span class="token punctuation">;</span> OUTPUT t<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span></code></pre>
</div>
<p>
In general, pushed-down predicates can be extracted from join
conditions such as
<code class="literal">
P1(T1,T2)
</code>
and
<code class="literal">
P(T2,T3)
</code>
. In this case, a pushed-down
predicate is guarded also by a flag that prevents checking the
predicate for the
<code class="literal">
NULL
</code>
-complemented row
generated by the corresponding outer join operation.
</p>
<p>
Access by key from one inner table to another in the same
nested join is prohibited if it is induced by a predicate from
the
<code class="literal">
WHERE
</code>
condition.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/using-date.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="using-date">
</a>
B.3.4.2 Problems Using DATE Columns
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045053677248">
</a>
<a class="indexterm" name="idm46045053676208">
</a>
<a class="indexterm" name="idm46045053674720">
</a>
<p>
The format of a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
value is
<code class="literal">
'
<em class="replaceable">
<code>
YYYY-MM-DD
</code>
</em>
'
</code>
.
According to standard SQL, no other format is permitted. You
should use this format in
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
expressions and in the
<code class="literal">
WHERE
</code>
clause of
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements. For example:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa50930392"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> <span class="token datatype">date</span> <span class="token operator">>=</span> <span class="token string">'2003-05-05'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
As a convenience, MySQL automatically converts a date to a
number if the date is used in numeric context and vice versa.
MySQL also permits a
<span class="quote">
“
<span class="quote">
relaxed
</span>
”
</span>
string format when
updating and in a
<code class="literal">
WHERE
</code>
clause that
compares a date to a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
,
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
, or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
column.
<span class="quote">
“
<span class="quote">
Relaxed
</span>
”
</span>
format means that any punctuation
character may be used as the separator between parts. For
example,
<code class="literal">
'2004-08-15'
</code>
and
<code class="literal">
'2004#08#15'
</code>
are equivalent. MySQL can also
convert a string containing no separators (such as
<code class="literal">
'20040815'
</code>
), provided it makes sense as a
date.
</p>
<p>
When you compare a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
,
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
,
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
, or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
to a constant string
with the
<code class="literal">
<
</code>
,
<code class="literal">
<=
</code>
,
<code class="literal">
=
</code>
,
<code class="literal">
>=
</code>
,
<code class="literal">
>
</code>
, or
<code class="literal">
BETWEEN
</code>
operators, MySQL normally converts the string to an internal
long integer for faster comparison (and also for a bit more
<span class="quote">
“
<span class="quote">
relaxed
</span>
”
</span>
string checking). However, this
conversion is subject to the following exceptions:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
When you compare two columns
</p>
</li>
<li class="listitem">
<p>
When you compare a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
,
<a class="link" href="time.html" title="13.2.3 The TIME Type">
<code class="literal">
TIME
</code>
</a>
,
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATETIME
</code>
</a>
, or
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
TIMESTAMP
</code>
</a>
column to an
expression
</p>
</li>
<li class="listitem">
<p>
When you use any comparison method other than those just
listed, such as
<code class="literal">
IN
</code>
or
<a class="link" href="string-comparison-functions.html#function_strcmp">
<code class="literal">
STRCMP()
</code>
</a>
.
</p>
</li>
</ul>
</div>
<p>
For those exceptions, the comparison is done by converting the
objects to strings and performing a string comparison.
</p>
<p>
To be on the safe side, assume that strings are compared as
strings and use the appropriate string functions if you want
to compare a temporal value to a string.
</p>
<p>
The special
<span class="quote">
“
<span class="quote">
zero
</span>
”
</span>
date
<code class="literal">
'0000-00-00'
</code>
can be stored and retrieved as
<code class="literal">
'0000-00-00'.
</code>
When a
<code class="literal">
'0000-00-00'
</code>
date is used through
Connector/ODBC, it is automatically converted to
<code class="literal">
NULL
</code>
because ODBC cannot handle that kind
of date.
</p>
<p>
Because MySQL performs the conversions just described, the
following statements work (assume that
<code class="literal">
idate
</code>
is a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
column):
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78882864"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token number">19970505</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'19970505'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'97-05-05'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'1997.05.05'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'1997 05 05'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>idate<span class="token punctuation">)</span> <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token string">'0000-00-00'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> idate <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> idate <span class="token operator">>=</span> <span class="token string">'1997-05-05'</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> idate <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> idate <span class="token operator">>=</span> <span class="token number">19970505</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> <span class="token function">MOD</span><span class="token punctuation">(</span>idate<span class="token punctuation">,</span><span class="token number">100</span><span class="token punctuation">)</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> idate <span class="token operator">>=</span> <span class="token number">19970505</span><span class="token punctuation">;</span>
<span class="token keyword">SELECT</span> idate <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> idate <span class="token operator">>=</span> <span class="token string">'19970505'</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
However, the following statement does not work:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa79543227"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> idate <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> <span class="token function">STRCMP</span><span class="token punctuation">(</span>idate<span class="token punctuation">,</span><span class="token string">'20030505'</span><span class="token punctuation">)</span><span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
<a class="link" href="string-comparison-functions.html#function_strcmp">
<code class="literal">
STRCMP()
</code>
</a>
is a string function,
so it converts
<code class="literal">
idate
</code>
to a string in
<code class="literal">
'
<em class="replaceable">
<code>
YYYY-MM-DD
</code>
</em>
'
</code>
format and performs a string comparison. It does not convert
<code class="literal">
'20030505'
</code>
to the date
<code class="literal">
'2003-05-05'
</code>
and perform a date comparison.
</p>
<p>
If you enable the
<a class="link" href="sql-mode.html#sqlmode_allow_invalid_dates">
<code class="literal">
ALLOW_INVALID_DATES
</code>
</a>
SQL
mode, MySQL permits you to store dates that are given only
limited checking: MySQL requires only that the day is in the
range from 1 to 31 and the month is in the range from 1 to 12.
This makes MySQL very convenient for Web applications where
you obtain year, month, and day in three different fields and
you want to store exactly what the user inserted (without date
validation).
</p>
<p>
MySQL permits you to store dates where the day or month and
day are zero. This is convenient if you want to store a
birthdate in a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
column and
you know only part of the date. To disallow zero month or day
parts in dates, enable the
<a class="link" href="sql-mode.html#sqlmode_no_zero_in_date">
<code class="literal">
NO_ZERO_IN_DATE
</code>
</a>
mode.
</p>
<p>
MySQL permits you to store a
<span class="quote">
“
<span class="quote">
zero
</span>
”
</span>
value of
<code class="literal">
'0000-00-00'
</code>
as a
<span class="quote">
“
<span class="quote">
dummy
date.
</span>
”
</span>
This is in some cases more convenient than using
<code class="literal">
NULL
</code>
values. If a date to be stored in a
<a class="link" href="datetime.html" title="13.2.2 The DATE, DATETIME, and TIMESTAMP Types">
<code class="literal">
DATE
</code>
</a>
column cannot be converted
to any reasonable value, MySQL stores
<code class="literal">
'0000-00-00'
</code>
. To disallow
<code class="literal">
'0000-00-00'
</code>
, enable the
<a class="link" href="sql-mode.html#sqlmode_no_zero_date">
<code class="literal">
NO_ZERO_DATE
</code>
</a>
mode.
</p>
<p>
To have MySQL check all dates and accept only legal dates
(unless overridden by
<code class="literal">
IGNORE
</code>
), set the
<a class="link" href="server-system-variables.html#sysvar_sql_mode">
<code class="literal">
sql_mode
</code>
</a>
system variable to
<code class="literal">
"NO_ZERO_IN_DATE,NO_ZERO_DATE"
</code>
.
</p>
</div>
<br/>
</div>
|
https://dev.mysql.com/doc/refman/8.4/en/mysql-command-options.html | <div id="docs-body">
<div class="section">
<div class="titlepage">
<div>
<div>
<h4 class="title">
<a name="mysql-command-options">
</a>
6.5.1.1 mysql Client Options
</h4>
</div>
</div>
</div>
<a class="indexterm" name="idm46045320152032">
</a>
<a class="indexterm" name="idm46045320150960">
</a>
<a class="indexterm" name="idm46045320149472">
</a>
<a class="indexterm" name="idm46045320147568">
</a>
<p>
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
supports the following options, which
can be specified on the command line or in the
<code class="literal">
[mysql]
</code>
and
<code class="literal">
[client]
</code>
groups of an option file. For information about option files
used by MySQL programs, see
<a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files">
Section 6.2.2.2, “Using Option Files”
</a>
.
</p>
<div class="table">
<a name="idm46045320142176">
</a>
<p class="title">
<b>
Table 6.10 mysql Client Options
</b>
</p>
<div class="table-contents">
<table frame="box" rules="all" summary="Command-line options available for the mysql client.">
<colgroup>
<col style="width: 31%"/>
<col style="width: 56%"/>
<col style="width: 12%"/>
</colgroup>
<thead>
<tr>
<th scope="col">
Option Name
</th>
<th scope="col">
Description
</th>
<th scope="col">
Introduced
</th>
</tr>
</thead>
<tbody>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
--auto-rehash
</a>
</th>
<td>
Enable automatic rehashing
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_auto-vertical-output">
--auto-vertical-output
</a>
</th>
<td>
Enable automatic vertical result set display
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_batch">
--batch
</a>
</th>
<td>
Do not use history file
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
--binary-as-hex
</a>
</th>
<td>
Display binary values in hexadecimal notation
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_binary-mode">
--binary-mode
</a>
</th>
<td>
Disable \r\n - to - \n translation and treatment of \0 as end-of-query
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_bind-address">
--bind-address
</a>
</th>
<td>
Use specified network interface to connect to MySQL Server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_character-sets-dir">
--character-sets-dir
</a>
</th>
<td>
Directory where character sets are installed
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_column-names">
--column-names
</a>
</th>
<td>
Write column names in results
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_column-type-info">
--column-type-info
</a>
</th>
<td>
Display result set metadata
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_comments">
--comments
</a>
</th>
<td>
Whether to retain or strip comments in statements sent to the server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_compress">
--compress
</a>
</th>
<td>
Compress all information sent between client and server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_compression-algorithms">
--compression-algorithms
</a>
</th>
<td>
Permitted compression algorithms for connections to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_connect-expired-password">
--connect-expired-password
</a>
</th>
<td>
Indicate to server that client can handle expired-password sandbox mode
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_connect-timeout">
--connect-timeout
</a>
</th>
<td>
Number of seconds before connection timeout
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_database">
--database
</a>
</th>
<td>
The database to use
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_debug">
--debug
</a>
</th>
<td>
Write debugging log; supported only if MySQL was built with debugging support
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_debug-check">
--debug-check
</a>
</th>
<td>
Print debugging information when program exits
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_debug-info">
--debug-info
</a>
</th>
<td>
Print debugging information, memory, and CPU statistics when program exits
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_default-auth">
--default-auth
</a>
</th>
<td>
Authentication plugin to use
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_default-character-set">
--default-character-set
</a>
</th>
<td>
Specify default character set
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_defaults-extra-file">
--defaults-extra-file
</a>
</th>
<td>
Read named option file in addition to usual option files
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_defaults-file">
--defaults-file
</a>
</th>
<td>
Read only named option file
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_defaults-group-suffix">
--defaults-group-suffix
</a>
</th>
<td>
Option group suffix value
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_delimiter">
--delimiter
</a>
</th>
<td>
Set the statement delimiter
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
--dns-srv-name
</a>
</th>
<td>
Use DNS SRV lookup for host information
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_enable-cleartext-plugin">
--enable-cleartext-plugin
</a>
</th>
<td>
Enable cleartext authentication plugin
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_execute">
--execute
</a>
</th>
<td>
Execute the statement and quit
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_force">
--force
</a>
</th>
<td>
Continue even if an SQL error occurs
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_get-server-public-key">
--get-server-public-key
</a>
</th>
<td>
Request RSA public key from server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_help">
--help
</a>
</th>
<td>
Display help message and exit
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_histignore">
--histignore
</a>
</th>
<td>
Patterns specifying which statements to ignore for logging
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_host">
--host
</a>
</th>
<td>
Host on which MySQL server is located
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_html">
--html
</a>
</th>
<td>
Produce HTML output
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ignore-spaces">
--ignore-spaces
</a>
</th>
<td>
Ignore spaces after function names
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_init-command">
--init-command
</a>
</th>
<td>
SQL statement to execute after connecting
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_init-command-add">
--init-command-add
</a>
</th>
<td>
Add an additional SQL statement to execute after connecting or re-connecting to MySQL server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_line-numbers">
--line-numbers
</a>
</th>
<td>
Write line numbers for errors
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
--load-data-local-dir
</a>
</th>
<td>
Directory for files named in LOAD DATA LOCAL statements
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
--local-infile
</a>
</th>
<td>
Enable or disable for LOCAL capability for LOAD DATA
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_login-path">
--login-path
</a>
</th>
<td>
Read login path options from .mylogin.cnf
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_max-allowed-packet">
--max-allowed-packet
</a>
</th>
<td>
Maximum packet length to send to or receive from server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_max-join-size">
--max-join-size
</a>
</th>
<td>
The automatic limit for rows in a join when using --safe-updates
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_named-commands">
--named-commands
</a>
</th>
<td>
Enable named mysql commands
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_net-buffer-length">
--net-buffer-length
</a>
</th>
<td>
Buffer size for TCP/IP and socket communication
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_network-namespace">
--network-namespace
</a>
</th>
<td>
Specify network namespace
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_no-auto-rehash">
--no-auto-rehash
</a>
</th>
<td>
Disable automatic rehashing
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_no-beep">
--no-beep
</a>
</th>
<td>
Do not beep when errors occur
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_no-defaults">
--no-defaults
</a>
</th>
<td>
Read no option files
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_no-login-paths">
--no-login-paths
</a>
</th>
<td>
Do not read login paths from the login path file
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_oci-config-file">
--oci-config-file
</a>
</th>
<td>
Defines an alternate location for the Oracle Cloud Infrastructure CLI configuration file.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_one-database">
--one-database
</a>
</th>
<td>
Ignore statements except those for the default database named on the command line
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_pager">
--pager
</a>
</th>
<td>
Use the given command for paging query output
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_password">
--password
</a>
</th>
<td>
Password to use when connecting to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_password1">
--password1
</a>
</th>
<td>
First multifactor authentication password to use when connecting to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_password2">
--password2
</a>
</th>
<td>
Second multifactor authentication password to use when connecting to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_password3">
--password3
</a>
</th>
<td>
Third multifactor authentication password to use when connecting to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_pipe">
--pipe
</a>
</th>
<td>
Connect to server using named pipe (Windows only)
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_plugin-authentication-kerberos-client-mode">
--plugin-authentication-kerberos-client-mode
</a>
</th>
<td>
Permit GSSAPI pluggable authentication through the MIT Kerberos library on Windows
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_plugin-authentication-webauthn-client-preserve-privacy">
--plugin-authentication-webauthn-client-preserve-privacy
</a>
</th>
<td>
Permit user to choose a key to be used for assertion
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_plugin-dir">
--plugin-dir
</a>
</th>
<td>
Directory where plugins are installed
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_port">
--port
</a>
</th>
<td>
TCP/IP port number for connection
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_print-defaults">
--print-defaults
</a>
</th>
<td>
Print default options
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_prompt">
--prompt
</a>
</th>
<td>
Set the prompt to the specified format
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_protocol">
--protocol
</a>
</th>
<td>
Transport protocol to use
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_quick">
--quick
</a>
</th>
<td>
Do not cache each query result
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_raw">
--raw
</a>
</th>
<td>
Write column values without escape conversion
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_reconnect">
--reconnect
</a>
</th>
<td>
If the connection to the server is lost, automatically try to reconnect
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_register-factor">
--register-factor
</a>
</th>
<td>
Multifactor authentication factors for which registration must be done
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
--safe-updates
</a>
,
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
--i-am-a-dummy
</a>
</th>
<td>
Allow only UPDATE and DELETE statements that specify key values
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_select-limit">
--select-limit
</a>
</th>
<td>
The automatic limit for SELECT statements when using --safe-updates
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_server-public-key-path">
--server-public-key-path
</a>
</th>
<td>
Path name to file containing RSA public key
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_shared-memory-base-name">
--shared-memory-base-name
</a>
</th>
<td>
Shared-memory name for shared-memory connections (Windows only)
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_show-warnings">
--show-warnings
</a>
</th>
<td>
Show warnings after each statement if there are any
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_sigint-ignore">
--sigint-ignore
</a>
</th>
<td>
Ignore SIGINT signals (typically the result of typing Control+C)
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_silent">
--silent
</a>
</th>
<td>
Silent mode
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
--skip-auto-rehash
</a>
</th>
<td>
Disable automatic rehashing
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_skip-column-names">
--skip-column-names
</a>
</th>
<td>
Do not write column names in results
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_skip-line-numbers">
--skip-line-numbers
</a>
</th>
<td>
Skip line numbers for errors
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_named-commands">
--skip-named-commands
</a>
</th>
<td>
Disable named mysql commands
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_pager">
--skip-pager
</a>
</th>
<td>
Disable paging
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_reconnect">
--skip-reconnect
</a>
</th>
<td>
Disable reconnecting
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_skip-system-command">
--skip-system-command
</a>
</th>
<td>
Disable system (\!) command
</td>
<td>
8.4.3
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_socket">
--socket
</a>
</th>
<td>
Unix socket file or Windows named pipe to use
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-ca
</a>
</th>
<td>
File that contains list of trusted SSL Certificate Authorities
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-capath
</a>
</th>
<td>
Directory that contains trusted SSL Certificate Authority certificate files
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-cert
</a>
</th>
<td>
File that contains X.509 certificate
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-cipher
</a>
</th>
<td>
Permissible ciphers for connection encryption
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-crl
</a>
</th>
<td>
File that contains certificate revocation lists
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-crlpath
</a>
</th>
<td>
Directory that contains certificate revocation-list files
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
--ssl-fips-mode
</a>
</th>
<td>
Whether to enable FIPS mode on client side
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-key
</a>
</th>
<td>
File that contains X.509 key
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-mode
</a>
</th>
<td>
Desired security state of connection to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-session-data
</a>
</th>
<td>
File that contains SSL session data
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_ssl">
--ssl-session-data-continue-on-failed-reuse
</a>
</th>
<td>
Whether to establish connections if session reuse fails
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_syslog">
--syslog
</a>
</th>
<td>
Log interactive statements to syslog
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_system-command">
--system-command
</a>
</th>
<td>
Enable or disable system (\!) command
</td>
<td>
8.4.3
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_table">
--table
</a>
</th>
<td>
Display output in tabular format
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_tee">
--tee
</a>
</th>
<td>
Append a copy of output to named file
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_telemetry_client">
--telemetry_client
</a>
</th>
<td>
Enables the telemetry client.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_bsp_max_export_batch_size">
--otel_bsp_max_export_batch_size
</a>
</th>
<td>
See variable OTEL_BSP_MAX_EXPORT_BATCH_SIZE.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_bsp_max_queue_size">
--otel_bsp_max_queue_size
</a>
</th>
<td>
See variable OTEL_BSP_MAX_QUEUE_SIZE.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_bsp_schedule_delay">
--otel_bsp_schedule_delay
</a>
</th>
<td>
See variable OTEL_BSP_SCHEDULE_DELAY.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_certificates">
--otel_exporter_otlp_traces_certificates
</a>
</th>
<td>
Not in use at this time. Reserved for future development.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_client_certificates">
--otel_exporter_otlp_traces_client_certificates
</a>
</th>
<td>
Not in use at this time. Reserved for future development.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_client_key">
--otel_exporter_otlp_traces_client_key
</a>
</th>
<td>
Not in use at this time. Reserved for future development.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_compression">
--otel_exporter_otlp_traces_compression
</a>
</th>
<td>
Compression type
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_endpoint">
--otel_exporter_otlp_traces_endpoint
</a>
</th>
<td>
The trace export endpoint
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_headers">
--otel_exporter_otlp_traces_headers
</a>
</th>
<td>
Key-value pairs to be used as headers associated with HTTP requests
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_protocol">
--otel_exporter_otlp_traces_protocol
</a>
</th>
<td>
The OTLP transport protocol
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_exporter_otlp_traces_timeout">
--otel_exporter_otlp_traces_timeout
</a>
</th>
<td>
Time OLTP exporter waits for each batch export
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel-help">
--otel-help
</a>
</th>
<td>
When enabled, prints help about telemetry_client options.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_log_level">
--otel_log_level
</a>
</th>
<td>
Controls which opentelemetry logs are printed in the server logs
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel_resource_attributes">
--otel_resource_attributes
</a>
</th>
<td>
See corresponding OpenTelemetry variable OTEL_RESOURCE_ATTRIBUTES.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="telemetry-trace-configuration.html#option_mysql_telemetry_client.otel-trace">
--otel-trace
</a>
</th>
<td>
This system variable controls whether telemetry traces are collected or not.
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_tls-ciphersuites">
--tls-ciphersuites
</a>
</th>
<td>
Permissible TLSv1.3 ciphersuites for encrypted connections
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_tls-sni-servername">
--tls-sni-servername
</a>
</th>
<td>
Server name supplied by the client
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_tls-version">
--tls-version
</a>
</th>
<td>
Permissible TLS protocols for encrypted connections
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_unbuffered">
--unbuffered
</a>
</th>
<td>
Flush the buffer after each query
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_user">
--user
</a>
</th>
<td>
MySQL user name to use when connecting to server
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_verbose">
--verbose
</a>
</th>
<td>
Verbose mode
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_version">
--version
</a>
</th>
<td>
Display version information and exit
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_vertical">
--vertical
</a>
</th>
<td>
Print query output rows vertically (one line per column value)
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_wait">
--wait
</a>
</th>
<td>
If the connection cannot be established, wait and retry instead of aborting
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_xml">
--xml
</a>
</th>
<td>
Produce XML output
</td>
<td>
</td>
</tr>
<tr>
<th scope="row">
<a class="link" href="mysql-command-options.html#option_mysql_zstd-compression-level">
--zstd-compression-level
</a>
</th>
<td>
Compression level for connections to server that use zstd compression
</td>
<td>
</td>
</tr>
</tbody>
</table>
</div>
<div class="table-contents">
<table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;">
<thead>
<tr>
<th scope="col" style="width: 318.25px;">
Option Name
</th>
<th scope="col" style="width: 332.672px;">
Description
</th>
<th scope="col" style="width: 87.0781px;">
Introduced
</th>
</tr>
</thead>
</table>
</div>
</div>
<br class="table-break"/>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p>
<a name="option_mysql_help">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_help">
<code class="option">
--help
</code>
</a>
,
<code class="option">
-?
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for help">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--help
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319662432">
</a>
<a class="indexterm" name="idm46045319660944">
</a>
<p>
Display a help message and exit.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_auto-rehash">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
<code class="option">
--auto-rehash
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for auto-rehash">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--auto-rehash
</code>
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-auto-rehash
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319648832">
</a>
<a class="indexterm" name="idm46045319647344">
</a>
<p>
Enable automatic rehashing. This option is on by default,
which enables database, table, and column name completion.
Use
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
<code class="option">
--disable-auto-rehash
</code>
</a>
to disable rehashing. That causes
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
to start faster, but you must issue the
<code class="literal">
rehash
</code>
command or its
<code class="literal">
\#
</code>
shortcut if you want to use name
completion.
</p>
<p>
To complete a name, enter the first part and press Tab. If
the name is unambiguous,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
completes
it. Otherwise, you can press Tab again to see the possible
names that begin with what you have typed so far. Completion
does not occur if there is no default database.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
This feature requires a MySQL client that is compiled with
the
<span class="bold">
<strong>
readline
</strong>
</span>
library.
Typically, the
<span class="bold">
<strong>
readline
</strong>
</span>
library is not available on Windows.
</p>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_auto-vertical-output">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_auto-vertical-output">
<code class="option">
--auto-vertical-output
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for auto-vertical-output">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--auto-vertical-output
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319629456">
</a>
<a class="indexterm" name="idm46045319627952">
</a>
<p>
Cause result sets to be displayed vertically if they are too
wide for the current window, and using normal tabular format
otherwise. (This applies to statements terminated by
<code class="literal">
;
</code>
or
<code class="literal">
\G
</code>
.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_batch">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_batch">
<code class="option">
--batch
</code>
</a>
,
<code class="option">
-B
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for batch">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--batch
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319616448">
</a>
<a class="indexterm" name="idm46045319614960">
</a>
<p>
Print results using tab as the column separator, with each
row on a new line. With this option,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
does not use the history file.
</p>
<p>
Batch mode results in nontabular output format and escaping
of special characters. Escaping may be disabled by using raw
mode; see the description for the
<a class="link" href="mysql-command-options.html#option_mysql_raw">
<code class="option">
--raw
</code>
</a>
option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_binary-as-hex">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for binary-as-hex">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--binary-as-hex
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE in noninteractive mode
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319597888">
</a>
<a class="indexterm" name="idm46045319596400">
</a>
<p>
When this option is given,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
displays
binary data using hexadecimal notation
(
<code class="literal">
0x
<em class="replaceable">
<code>
value
</code>
</em>
</code>
).
This occurs whether the overall output display format is
tabular, vertical, HTML, or XML.
</p>
<p>
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
when enabled
affects display of all binary strings, including those
returned by functions such as
<a class="link" href="string-functions.html#function_char">
<code class="literal">
CHAR()
</code>
</a>
and
<a class="link" href="string-functions.html#function_unhex">
<code class="literal">
UNHEX()
</code>
</a>
. The following
example demonstrates this using the ASCII code for
<code class="literal">
A
</code>
(65 decimal, 41 hexadecimal):
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
disabled:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa71423711"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">0x41</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">UNHEX</span><span class="token punctuation">(</span><span class="token string">'41'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CHAR(0x41) <span class="token punctuation">|</span> UNHEX('41') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> A <span class="token punctuation">|</span> A <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
enabled:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa919940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">0x41</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">UNHEX</span><span class="token punctuation">(</span><span class="token string">'41'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CHAR(0x41) <span class="token punctuation">|</span> UNHEX('41') <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 0x41 <span class="token punctuation">|</span> 0x41 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
</ul>
</div>
<p>
To write a binary string expression so that it displays as a
character string regardless of whether
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--binary-as-hex
</code>
</a>
is enabled,
use these techniques:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The
<a class="link" href="string-functions.html#function_char">
<code class="literal">
CHAR()
</code>
</a>
function has a
<code class="literal">
USING
<em class="replaceable">
<code>
charset
</code>
</em>
</code>
clause:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa50743476"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">0x41</span> <span class="token keyword">USING</span> utf8mb4<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CHAR(0x41 USING utf8mb4) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> A <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
More generally, use
<a class="link" href="cast-functions.html#function_convert">
<code class="literal">
CONVERT()
</code>
</a>
to convert an
expression to a given character set:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa31394599"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">CONVERT</span><span class="token punctuation">(</span><span class="token function">UNHEX</span><span class="token punctuation">(</span><span class="token string">'41'</span><span class="token punctuation">)</span> <span class="token keyword">USING</span> utf8mb4<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CONVERT(UNHEX('41') USING utf8mb4) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> A <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
</ul>
</div>
<p>
When
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
operates in interactive mode,
this option is enabled by default. In addition, output from
the
<code class="literal">
status
</code>
(or
<code class="literal">
\s
</code>
)
command includes this line when the option is enabled
implicitly or explicitly:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa99496713"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">Binary data as: Hexadecimal</code></pre>
</div>
<p>
To disable hexadecimal notation, use
<a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex">
<code class="option">
--skip-binary-as-hex
</code>
</a>
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_binary-mode">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_binary-mode">
<code class="option">
--binary-mode
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for binary-mode">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--binary-mode
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319555248">
</a>
<a class="indexterm" name="idm46045319553760">
</a>
<p>
This option helps when processing
<a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files">
<span class="command">
<strong>
mysqlbinlog
</strong>
</span>
</a>
output that may contain
<a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types">
<code class="literal">
BLOB
</code>
</a>
values. By default,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
translates
<code class="literal">
\r\n
</code>
in statement strings to
<code class="literal">
\n
</code>
and interprets
<code class="literal">
\0
</code>
as the statement terminator.
<a class="link" href="mysql-command-options.html#option_mysql_binary-mode">
<code class="option">
--binary-mode
</code>
</a>
disables both
features. It also disables all
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
commands except
<code class="literal">
charset
</code>
and
<code class="literal">
delimiter
</code>
in noninteractive mode (for
input piped to
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
or loaded using the
<code class="literal">
source
</code>
command).
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_bind-address">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_bind-address">
<code class="option">
--bind-address=
<em class="replaceable">
<code>
ip_address
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for bind-address">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--bind-address=ip_address
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319532160">
</a>
<a class="indexterm" name="idm46045319530672">
</a>
<p>
On a computer having multiple network interfaces, use this
option to select which interface to use for connecting to
the MySQL server.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_character-sets-dir">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_character-sets-dir">
<code class="option">
--character-sets-dir=
<em class="replaceable">
<code>
dir_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for character-sets-dir">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--character-sets-dir=dir_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Directory name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319518544">
</a>
<a class="indexterm" name="idm46045319517040">
</a>
<p>
The directory where character sets are installed. See
<a class="xref" href="charset-configuration.html" title="12.15 Character Set Configuration">
Section 12.15, “Character Set Configuration”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_column-names">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_column-names">
<code class="option">
--column-names
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for column-names">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--column-names
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319506544">
</a>
<a class="indexterm" name="idm46045319505056">
</a>
<p>
Write column names in results.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_column-type-info">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_column-type-info">
<code class="option">
--column-type-info
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for column-type-info">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--column-type-info
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319495408">
</a>
<a class="indexterm" name="idm46045319493920">
</a>
<p>
Display result set metadata. This information corresponds to
the contents of C API
<code class="literal">
MYSQL_FIELD
</code>
data
structures. See
<a class="ulink" href="/doc/c-api/8.4/en/c-api-data-structures.html" target="_top">
C API Basic Data Structures
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_comments">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_comments">
<code class="option">
--comments
</code>
</a>
,
<code class="option">
-c
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for comments">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--comments
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
TRUE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319477856">
</a>
<a class="indexterm" name="idm46045319476368">
</a>
<p>
Whether to preserve or strip comments in statements sent to
the server. The default is to preserve them; to strip them,
start
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
with
<code class="option">
--skip-comments
</code>
.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
The
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client always passes
optimizer hints to the server, regardless of whether this
option is given.
</p>
<p>
Comment stripping is deprecated. Expect this feature and
the options to control it to be removed in a future MySQL
release.
</p>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_compress">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_compress">
<code class="option">
--compress
</code>
</a>
,
<code class="option">
-C
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for compress">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--compress[={OFF|ON}]
</code>
</td>
</tr>
<tr>
<th>
Deprecated
</th>
<td>
Yes
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
OFF
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319455440">
</a>
<a class="indexterm" name="idm46045319453952">
</a>
<p>
Compress all information sent between the client and the
server if possible. See
<a class="xref" href="connection-compression-control.html" title="6.2.8 Connection Compression Control">
Section 6.2.8, “Connection Compression Control”
</a>
.
</p>
<p>
This option is deprecated. Expect it to be removed in a
future version of MySQL. See
<a class="xref" href="connection-compression-control.html#connection-compression-legacy-configuration" title="Configuring Legacy Connection Compression">
Configuring Legacy Connection Compression
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_compression-algorithms">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_compression-algorithms">
<code class="option">
--compression-algorithms=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for compression-algorithms">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--compression-algorithms=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Set
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
uncompressed
</code>
</td>
</tr>
<tr>
<th>
Valid Values
</th>
<td>
<p class="valid-value">
<code class="literal">
zlib
</code>
</p>
<p class="valid-value">
<code class="literal">
zstd
</code>
</p>
<p class="valid-value">
<code class="literal">
uncompressed
</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319432720">
</a>
<a class="indexterm" name="idm46045319431216">
</a>
<p>
The permitted compression algorithms for connections to the
server. The available algorithms are the same as for the
<a class="link" href="server-system-variables.html#sysvar_protocol_compression_algorithms">
<code class="literal">
protocol_compression_algorithms
</code>
</a>
system variable. The default value is
<code class="literal">
uncompressed
</code>
.
</p>
<p>
For more information, see
<a class="xref" href="connection-compression-control.html" title="6.2.8 Connection Compression Control">
Section 6.2.8, “Connection Compression Control”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_connect-expired-password">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_connect-expired-password">
<code class="option">
--connect-expired-password
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for connect-expired-password">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--connect-expired-password
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319418208">
</a>
<a class="indexterm" name="idm46045319416704">
</a>
<p>
Indicate to the server that the client can handle sandbox
mode if the account used to connect has an expired password.
This can be useful for noninteractive invocations of
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
because normally the server
disconnects noninteractive clients that attempt to connect
using an account with an expired password. (See
<a class="xref" href="expired-password-handling.html" title="8.2.16 Server Handling of Expired Passwords">
Section 8.2.16, “Server Handling of Expired Passwords”
</a>
.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_connect-timeout">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_connect-timeout">
<code class="option">
--connect-timeout=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for connect-timeout">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--connect-timeout=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
0
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319399888">
</a>
<a class="indexterm" name="idm46045319398400">
</a>
<p>
The number of seconds before connection timeout. (Default
value is
<code class="literal">
0
</code>
.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_database">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_database">
<code class="option">
--database=
<em class="replaceable">
<code>
db_name
</code>
</em>
</code>
</a>
,
<code class="option">
-D
<em class="replaceable">
<code>
db_name
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for database">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--database=dbname
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319385056">
</a>
<a class="indexterm" name="idm46045319383568">
</a>
<p>
The database to use. This is useful primarily in an option
file.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_debug">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_debug">
<code class="option">
--debug[=
<em class="replaceable">
<code>
debug_options
</code>
</em>
]
</code>
</a>
,
<code class="option">
-#
[
<em class="replaceable">
<code>
debug_options
</code>
</em>
]
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for debug">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--debug[=debug_options]
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
d:t:o,/tmp/mysql.trace
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319368176">
</a>
<a class="indexterm" name="idm46045319366688">
</a>
<p>
Write a debugging log. A typical
<em class="replaceable">
<code>
debug_options
</code>
</em>
string is
<code class="literal">
d:t:o,
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
.
The default is
<code class="literal">
d:t:o,/tmp/mysql.trace
</code>
.
</p>
<p>
This option is available only if MySQL was built using
<a class="link" href="source-configuration-options.html#option_cmake_with_debug">
<code class="option">
WITH_DEBUG
</code>
</a>
. MySQL release
binaries provided by Oracle are
<span class="emphasis">
<em>
not
</em>
</span>
built using this option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_debug-check">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_debug-check">
<code class="option">
--debug-check
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for debug-check">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--debug-check
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319348400">
</a>
<a class="indexterm" name="idm46045319346912">
</a>
<p>
Print some debugging information when the program exits.
</p>
<p>
This option is available only if MySQL was built using
<a class="link" href="source-configuration-options.html#option_cmake_with_debug">
<code class="option">
WITH_DEBUG
</code>
</a>
. MySQL release
binaries provided by Oracle are
<span class="emphasis">
<em>
not
</em>
</span>
built using this option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_debug-info">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_debug-info">
<code class="option">
--debug-info
</code>
</a>
,
<code class="option">
-T
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for debug-info">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--debug-info
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319330448">
</a>
<a class="indexterm" name="idm46045319328960">
</a>
<p>
Print debugging information and memory and CPU usage
statistics when the program exits.
</p>
<p>
This option is available only if MySQL was built using
<a class="link" href="source-configuration-options.html#option_cmake_with_debug">
<code class="option">
WITH_DEBUG
</code>
</a>
. MySQL release
binaries provided by Oracle are
<span class="emphasis">
<em>
not
</em>
</span>
built using this option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_default-auth">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_default-auth">
<code class="option">
--default-auth=
<em class="replaceable">
<code>
plugin
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for default-auth">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--default-auth=plugin
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319314960">
</a>
<a class="indexterm" name="idm46045319313472">
</a>
<p>
A hint about which client-side authentication plugin to use.
See
<a class="xref" href="pluggable-authentication.html" title="8.2.17 Pluggable Authentication">
Section 8.2.17, “Pluggable Authentication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_default-character-set">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_default-character-set">
<code class="option">
--default-character-set=
<em class="replaceable">
<code>
charset_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for default-character-set">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--default-character-set=charset_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319300704">
</a>
<a class="indexterm" name="idm46045319299200">
</a>
<p>
Use
<em class="replaceable">
<code>
charset_name
</code>
</em>
as the default
character set for the client and connection.
</p>
<p>
This option can be useful if the operating system uses one
character set and the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client by
default uses another. In this case, output may be formatted
incorrectly. You can usually fix such issues by using this
option to force the client to use the system character set
instead.
</p>
<p>
For more information, see
<a class="xref" href="charset-connection.html" title="12.4 Connection Character Sets and Collations">
Section 12.4, “Connection Character Sets and Collations”
</a>
, and
<a class="xref" href="charset-configuration.html" title="12.15 Character Set Configuration">
Section 12.15, “Character Set Configuration”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_defaults-extra-file">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_defaults-extra-file">
<code class="option">
--defaults-extra-file=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for defaults-extra-file">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--defaults-extra-file=file_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
File name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319282816">
</a>
<a class="indexterm" name="idm46045319281312">
</a>
<p>
Read this option file after the global option file but (on
Unix) before the user option file. If the file does not
exist or is otherwise inaccessible, an error occurs. If
<em class="replaceable">
<code>
file_name
</code>
</em>
is not an absolute path
name, it is interpreted relative to the current directory.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_defaults-file">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_defaults-file">
<code class="option">
--defaults-file=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for defaults-file">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--defaults-file=file_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
File name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319267408">
</a>
<a class="indexterm" name="idm46045319265920">
</a>
<p>
Use only the given option file. If the file does not exist
or is otherwise inaccessible, an error occurs. If
<em class="replaceable">
<code>
file_name
</code>
</em>
is not an absolute path
name, it is interpreted relative to the current directory.
</p>
<p>
Exception: Even with
<a class="link" href="option-file-options.html#option_general_defaults-file">
<code class="option">
--defaults-file
</code>
</a>
, client
programs read
<code class="filename">
.mylogin.cnf
</code>
.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_defaults-group-suffix">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_defaults-group-suffix">
<code class="option">
--defaults-group-suffix=
<em class="replaceable">
<code>
str
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for defaults-group-suffix">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--defaults-group-suffix=str
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319249952">
</a>
<a class="indexterm" name="idm46045319248448">
</a>
<p>
Read not only the usual option groups, but also groups with
the usual names and a suffix of
<em class="replaceable">
<code>
str
</code>
</em>
. For example,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
normally reads the
<code class="literal">
[client]
</code>
and
<code class="literal">
[mysql]
</code>
groups. If this option is given as
<a class="link" href="mysql-command-options.html#option_mysql_defaults-group-suffix">
<code class="option">
--defaults-group-suffix=_other
</code>
</a>
,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
also reads the
<code class="literal">
[client_other]
</code>
and
<code class="literal">
[mysql_other]
</code>
groups.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_delimiter">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_delimiter">
<code class="option">
--delimiter=
<em class="replaceable">
<code>
str
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for delimiter">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--delimiter=str
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
;
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319226016">
</a>
<a class="indexterm" name="idm46045319224528">
</a>
<p>
Set the statement delimiter. The default is the semicolon
character (
<code class="literal">
;
</code>
).
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_disable-named-commands">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_disable-named-commands">
<code class="option">
--disable-named-commands
</code>
</a>
</p>
<a class="indexterm" name="idm46045319219472">
</a>
<a class="indexterm" name="idm46045319217984">
</a>
<p>
Disable named commands. Use the
<code class="literal">
\*
</code>
form
only, or use named commands only at the beginning of a line
ending with a semicolon (
<code class="literal">
;
</code>
).
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
starts with this option
<span class="emphasis">
<em>
enabled
</em>
</span>
by default. However, even with
this option, long-format commands still work from the first
line. See
<a class="xref" href="mysql-commands.html" title="6.5.1.2 mysql Client Commands">
Section 6.5.1.2, “mysql Client Commands”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_dns-srv-name">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name=
<em class="replaceable">
<code>
name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for dns-srv-name">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--dns-srv-name=name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319202000">
</a>
<a class="indexterm" name="idm46045319200512">
</a>
<a class="indexterm" name="idm46045319199024">
</a>
<p>
Specifies the name of a DNS SRV record that determines the
candidate hosts to use for establishing a connection to a
MySQL server. For information about DNS SRV support in
MySQL, see
<a class="xref" href="connecting-using-dns-srv.html" title="6.2.6 Connecting to the Server Using DNS SRV Records">
Section 6.2.6, “Connecting to the Server Using DNS SRV Records”
</a>
.
</p>
<p>
Suppose that DNS is configured with this SRV information for
the
<code class="literal">
example.com
</code>
domain:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-simple"><div class="docs-select-all right" id="sa51594832"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">Name TTL Class Priority Weight Port Target
_mysql<span class="token punctuation">.</span>_tcp<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com<span class="token punctuation">.</span> 86400 IN SRV 0 5 3306 host1<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com
_mysql<span class="token punctuation">.</span>_tcp<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com<span class="token punctuation">.</span> 86400 IN SRV 0 10 3306 host2<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com
_mysql<span class="token punctuation">.</span>_tcp<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com<span class="token punctuation">.</span> 86400 IN SRV 10 5 3306 host3<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com
_mysql<span class="token punctuation">.</span>_tcp<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com<span class="token punctuation">.</span> 86400 IN SRV 20 5 3306 host4<span class="token punctuation">.</span>example<span class="token punctuation">.</span>com</code></pre>
</div>
<p>
To use that DNS SRV record, invoke
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa44568528"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--dns-srv-name</span><span class="token attr-value"><span class="token punctuation">=</span>_mysql._tcp.example.com</span></code></pre>
</div>
<p>
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
then attempts a connection to each
server in the group until a successful connection is
established. A failure to connect occurs only if a
connection cannot be established to any of the servers. The
priority and weight values in the DNS SRV record determine
the order in which servers should be tried.
</p>
<p>
When invoked with
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
attempts to establish TCP
connections only.
</p>
<p>
The
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
option
takes precedence over the
<a class="link" href="mysql-command-options.html#option_mysql_host">
<code class="option">
--host
</code>
</a>
option if both are
given.
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
causes
connection establishment to use the
<a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect-dns-srv.html" target="_top">
<code class="literal">
mysql_real_connect_dns_srv()
</code>
</a>
C API function rather than
<a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top">
<code class="literal">
mysql_real_connect()
</code>
</a>
.
However, if the
<code class="literal">
connect
</code>
command is
subsequently used at runtime and specifies a host name
argument, that host name takes precedence over any
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
option given at
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
startup to specify a DNS SRV
record.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_enable-cleartext-plugin">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_enable-cleartext-plugin">
<code class="option">
--enable-cleartext-plugin
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for enable-cleartext-plugin">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--enable-cleartext-plugin
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319165632">
</a>
<a class="indexterm" name="idm46045319164128">
</a>
<p>
Enable the
<code class="literal">
mysql_clear_password
</code>
cleartext
authentication plugin. (See
<a class="xref" href="cleartext-pluggable-authentication.html" title="8.4.1.4 Client-Side Cleartext Pluggable Authentication">
Section 8.4.1.4, “Client-Side Cleartext Pluggable Authentication”
</a>
.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_execute">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_execute">
<code class="option">
--execute=
<em class="replaceable">
<code>
statement
</code>
</em>
</code>
</a>
,
<code class="option">
-e
<em class="replaceable">
<code>
statement
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for execute">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--execute=statement
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319149984">
</a>
<a class="indexterm" name="idm46045319148496">
</a>
<p>
Execute the statement and quit. The default output format is
like that produced with
<a class="link" href="mysql-command-options.html#option_mysql_batch">
<code class="option">
--batch
</code>
</a>
. See
<a class="xref" href="command-line-options.html" title="6.2.2.1 Using Options on the Command Line">
Section 6.2.2.1, “Using Options on the Command Line”
</a>
, for some examples.
With this option,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
does not use the
history file.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_force">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_force">
<code class="option">
--force
</code>
</a>
,
<code class="option">
-f
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for force">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--force
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319135488">
</a>
<a class="indexterm" name="idm46045319134000">
</a>
<p>
Continue even if an SQL error occurs.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_get-server-public-key">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_get-server-public-key">
<code class="option">
--get-server-public-key
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for get-server-public-key">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--get-server-public-key
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319122288">
</a>
<a class="indexterm" name="idm46045319120784">
</a>
<p>
Request from the server the public key required for RSA key
pair-based password exchange. This option applies to clients
that authenticate with the
<code class="literal">
caching_sha2_password
</code>
authentication
plugin. For that plugin, the server does not send the public
key unless requested. This option is ignored for accounts
that do not authenticate with that plugin. It is also
ignored if RSA-based password exchange is not used, as is
the case when the client connects to the server using a
secure connection.
</p>
<p>
If
<a class="link" href="mysql-command-options.html#option_mysql_server-public-key-path">
<code class="option">
--server-public-key-path=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
is given and specifies a valid public key file, it takes
precedence over
<a class="link" href="mysql-command-options.html#option_mysql_get-server-public-key">
<code class="option">
--get-server-public-key
</code>
</a>
.
</p>
<p>
For information about the
<code class="literal">
caching_sha2_password
</code>
plugin, see
<a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication">
Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_histignore">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_histignore">
<code class="option">
--histignore
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for histignore">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--histignore=pattern_list
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319103168">
</a>
<a class="indexterm" name="idm46045319101680">
</a>
<p>
A list of one or more colon-separated patterns specifying
statements to ignore for logging purposes. These patterns
are added to the default pattern list
(
<code class="literal">
"*IDENTIFIED*:*PASSWORD*"
</code>
). The value
specified for this option affects logging of statements
written to the history file, and to
<code class="literal">
syslog
</code>
if the
<a class="link" href="mysql-command-options.html#option_mysql_syslog">
<code class="option">
--syslog
</code>
</a>
option is given. For
more information, see
<a class="xref" href="mysql-logging.html" title="6.5.1.3 mysql Client Logging">
Section 6.5.1.3, “mysql Client Logging”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_host">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_host">
<code class="option">
--host=
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
</a>
,
<code class="option">
-h
<em class="replaceable">
<code>
host_name
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for host">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--host=host_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
localhost
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319083200">
</a>
<a class="indexterm" name="idm46045319081712">
</a>
<p>
Connect to the MySQL server on the given host.
</p>
<p>
The
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
option
takes precedence over the
<a class="link" href="mysql-command-options.html#option_mysql_host">
<code class="option">
--host
</code>
</a>
option if both are
given.
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
causes
connection establishment to use the
<a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect-dns-srv.html" target="_top">
<code class="literal">
mysql_real_connect_dns_srv()
</code>
</a>
C API function rather than
<a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top">
<code class="literal">
mysql_real_connect()
</code>
</a>
.
However, if the
<code class="literal">
connect
</code>
command is
subsequently used at runtime and specifies a host name
argument, that host name takes precedence over any
<a class="link" href="mysql-command-options.html#option_mysql_dns-srv-name">
<code class="option">
--dns-srv-name
</code>
</a>
option given at
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
startup to specify a DNS SRV
record.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_html">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_html">
<code class="option">
--html
</code>
</a>
,
<code class="option">
-H
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for html">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--html
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319062672">
</a>
<a class="indexterm" name="idm46045319061184">
</a>
<p>
Produce HTML output.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_ignore-spaces">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_ignore-spaces">
<code class="option">
--ignore-spaces
</code>
</a>
,
<code class="option">
-i
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for ignore-spaces">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--ignore-spaces
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319051072">
</a>
<a class="indexterm" name="idm46045319049584">
</a>
<p>
Ignore spaces after function names. The effect of this is
described in the discussion for the
<a class="link" href="sql-mode.html#sqlmode_ignore_space">
<code class="literal">
IGNORE_SPACE
</code>
</a>
SQL mode (see
<a class="xref" href="sql-mode.html" title="7.1.11 Server SQL Modes">
Section 7.1.11, “Server SQL Modes”
</a>
).
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_init-command">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_init-command">
<code class="option">
--init-command=str
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for init-command">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--init-command=str
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319037808">
</a>
<a class="indexterm" name="idm46045319036320">
</a>
<p>
Single SQL statement to execute after connecting to the
server. If auto-reconnect is enabled, the statement is
executed again after reconnection occurs. The definition
resets existing statements defined by it or
<a class="link" href="mysql-command-options.html#option_mysql_init-command-add">
<code class="option">
init-command-add
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_init-command-add">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_init-command-add">
<code class="option">
--init-command-add=str
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for init-command-add">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--init-command-add=str
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319025456">
</a>
<a class="indexterm" name="idm46045319023968">
</a>
<p>
Add an additional SQL statement to execute after connecting
or reconnecting to the MySQL server. It's usable without
<a class="link" href="mysql-command-options.html#option_mysql_init-command">
<code class="option">
--init-command
</code>
</a>
but has no
effect if used before it because
<a class="link" href="mysql-command-options.html#option_mysql_init-command">
<code class="option">
init-command
</code>
</a>
resets the list
of commands to call.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_line-numbers">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_line-numbers">
<code class="option">
--line-numbers
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for line-numbers">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--line-numbers
</code>
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-line-numbers
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045319009680">
</a>
<a class="indexterm" name="idm46045319008192">
</a>
<p>
Write line numbers for errors. Disable this with
<a class="link" href="mysql-command-options.html#option_mysql_skip-line-numbers">
<code class="option">
--skip-line-numbers
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_load-data-local-dir">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir=
<em class="replaceable">
<code>
dir_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for load-data-local-dir">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--load-data-local-dir=dir_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Directory name
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
empty string
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318992720">
</a>
<a class="indexterm" name="idm46045318991216">
</a>
<p>
This option affects the client-side
<code class="literal">
LOCAL
</code>
capability for
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
operations. It specifies the directory in which files named
in
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
LOCAL
</code>
</a>
statements must be located. The effect of
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
depends
on whether
<code class="literal">
LOCAL
</code>
data loading is enabled
or disabled:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
If
<code class="literal">
LOCAL
</code>
data loading is enabled,
either by default in the MySQL client library or by
specifying
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile[=1]
</code>
</a>
, the
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
option is ignored.
</p>
</li>
<li class="listitem">
<p>
If
<code class="literal">
LOCAL
</code>
data loading is disabled,
either by default in the MySQL client library or by
specifying
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile=0
</code>
</a>
, the
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
option applies.
</p>
</li>
</ul>
</div>
<p>
When
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
applies, the option value designates the directory in which
local data files must be located. Comparison of the
directory path name and the path name of files to be loaded
is case-sensitive regardless of the case sensitivity of the
underlying file system. If the option value is the empty
string, it names no directory, with the result that no files
are permitted for local data loading.
</p>
<p>
For example, to explicitly disable local data loading except
for files located in the
<code class="filename">
/my/local/data
</code>
directory, invoke
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
like this:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa67815738"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--local-infile</span><span class="token attr-value"><span class="token punctuation">=</span>0</span> <span class="token constant">--load-data-local-dir</span><span class="token attr-value"><span class="token punctuation">=</span>/my/local/data</span></code></pre>
</div>
<p>
When both
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile
</code>
</a>
and
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
are
given, the order in which they are given does not matter.
</p>
<p>
Successful use of
<code class="literal">
LOCAL
</code>
load operations
within
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
also requires that the
server permits local loading; see
<a class="xref" href="load-data-local-security.html" title="8.1.6 Security Considerations for LOAD DATA LOCAL">
Section 8.1.6, “Security Considerations for LOAD DATA LOCAL”
</a>
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_local-infile">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile[={0|1}]
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for local-infile">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--local-infile[={0|1}]
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318953280">
</a>
<a class="indexterm" name="idm46045318951792">
</a>
<p>
By default,
<code class="literal">
LOCAL
</code>
capability for
<a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement">
<code class="literal">
LOAD DATA
</code>
</a>
is determined by
the default compiled into the MySQL client library. To
enable or disable
<code class="literal">
LOCAL
</code>
data loading
explicitly, use the
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile
</code>
</a>
option. When
given with no value, the option enables
<code class="literal">
LOCAL
</code>
data loading. When given as
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile=0
</code>
</a>
or
<a class="link" href="mysql-command-options.html#option_mysql_local-infile">
<code class="option">
--local-infile=1
</code>
</a>
, the option
disables or enables
<code class="literal">
LOCAL
</code>
data loading.
</p>
<p>
If
<code class="literal">
LOCAL
</code>
capability is disabled, the
<a class="link" href="mysql-command-options.html#option_mysql_load-data-local-dir">
<code class="option">
--load-data-local-dir
</code>
</a>
option
can be used to permit restricted local loading of files
located in a designated directory.
</p>
<p>
Successful use of
<code class="literal">
LOCAL
</code>
load operations
within
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
also requires that the
server permits local loading; see
<a class="xref" href="load-data-local-security.html" title="8.1.6 Security Considerations for LOAD DATA LOCAL">
Section 8.1.6, “Security Considerations for LOAD DATA LOCAL”
</a>
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_login-path">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_login-path">
<code class="option">
--login-path=
<em class="replaceable">
<code>
name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for login-path">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--login-path=name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318927088">
</a>
<a class="indexterm" name="idm46045318925600">
</a>
<p>
Read options from the named login path in the
<code class="filename">
.mylogin.cnf
</code>
login path file. A
<span class="quote">
“
<span class="quote">
login path
</span>
”
</span>
is an option group containing
options that specify which MySQL server to connect to and
which account to authenticate as. To create or modify a
login path file, use the
<a class="link" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility">
<span class="command">
<strong>
mysql_config_editor
</strong>
</span>
</a>
utility. See
<a class="xref" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility">
Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”
</a>
.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_no-login-paths">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_no-login-paths">
<code class="option">
--no-login-paths
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for no-login-paths">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--no-login-paths
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318911456">
</a>
<a class="indexterm" name="idm46045318909968">
</a>
<p>
Skips reading options from the login path file.
</p>
<p>
See
<a class="link" href="mysql-command-options.html#option_mysql_login-path">
<code class="option">
--login-path
</code>
</a>
for related
information.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_max-allowed-packet">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_max-allowed-packet">
<code class="option">
--max-allowed-packet=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for max-allowed-packet">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--max-allowed-packet=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
16777216
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318892928">
</a>
<a class="indexterm" name="idm46045318891424">
</a>
<p>
The maximum size of the buffer for client/server
communication. The default is 16MB, the maximum is 1GB.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_max-join-size">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_max-join-size">
<code class="option">
--max-join-size=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for max-join-size">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--max-join-size=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
1000000
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318876880">
</a>
<a class="indexterm" name="idm46045318875392">
</a>
<p>
The automatic limit for rows in a join when using
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--safe-updates
</code>
</a>
. (Default value
is 1,000,000.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_named-commands">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_named-commands">
<code class="option">
--named-commands
</code>
</a>
,
<code class="option">
-G
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for named-commands">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--named-commands
</code>
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-named-commands
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318861824">
</a>
<a class="indexterm" name="idm46045318860336">
</a>
<p>
Enable named
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
commands. Long-format
commands are permitted, not just short-format commands. For
example,
<code class="literal">
quit
</code>
and
<code class="literal">
\q
</code>
both are recognized. Use
<a class="link" href="mysql-command-options.html#option_mysql_named-commands">
<code class="option">
--skip-named-commands
</code>
</a>
to disable named commands. See
<a class="xref" href="mysql-commands.html" title="6.5.1.2 mysql Client Commands">
Section 6.5.1.2, “mysql Client Commands”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_net-buffer-length">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_net-buffer-length">
<code class="option">
--net-buffer-length=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for net-buffer-length">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--net-buffer-length=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
16384
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318841424">
</a>
<a class="indexterm" name="idm46045318839920">
</a>
<p>
The buffer size for TCP/IP and socket communication.
(Default value is 16KB.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_network-namespace">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_network-namespace">
<code class="option">
--network-namespace=
<em class="replaceable">
<code>
name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for network-namespace">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--network-namespace=name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318827840">
</a>
<a class="indexterm" name="idm46045318826336">
</a>
<p>
The network namespace to use for TCP/IP connections. If
omitted, the connection uses the default (global) namespace.
For information about network namespaces, see
<a class="xref" href="network-namespace-support.html" title="7.1.14 Network Namespace Support">
Section 7.1.14, “Network Namespace Support”
</a>
.
</p>
<p>
This option is available only on platforms that implement
network namespace support.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_no-auto-rehash">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
<code class="option">
--no-auto-rehash
</code>
</a>
,
<code class="option">
-A
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for no-auto-rehash">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--no-auto-rehash
</code>
</td>
</tr>
<tr>
<th>
Deprecated
</th>
<td>
Yes
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318812720">
</a>
<a class="indexterm" name="idm46045318811232">
</a>
<p>
This has the same effect as
<code class="option">
--skip-auto-rehash
</code>
.
See the description for
<a class="link" href="mysql-command-options.html#option_mysql_auto-rehash">
<code class="option">
--auto-rehash
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_no-beep">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_no-beep">
<code class="option">
--no-beep
</code>
</a>
,
<code class="option">
-b
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for no-beep">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--no-beep
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318799536">
</a>
<a class="indexterm" name="idm46045318798048">
</a>
<p>
Do not beep when errors occur.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_no-defaults">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_no-defaults">
<code class="option">
--no-defaults
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for no-defaults">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--no-defaults
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318788400">
</a>
<a class="indexterm" name="idm46045318786912">
</a>
<p>
Do not read any option files. If program startup fails due
to reading unknown options from an option file,
<a class="link" href="mysql-command-options.html#option_mysql_no-defaults">
<code class="option">
--no-defaults
</code>
</a>
can be used to
prevent them from being read.
</p>
<p>
The exception is that the
<code class="filename">
.mylogin.cnf
</code>
file is read in all cases, if it exists. This permits
passwords to be specified in a safer way than on the command
line even when
<a class="link" href="mysql-command-options.html#option_mysql_no-defaults">
<code class="option">
--no-defaults
</code>
</a>
is used. To create
<code class="filename">
.mylogin.cnf
</code>
, use
the
<a class="link" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility">
<span class="command">
<strong>
mysql_config_editor
</strong>
</span>
</a>
utility. See
<a class="xref" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility">
Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility”
</a>
.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_oci-config-file">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_oci-config-file">
<code class="option">
--oci-config-file=
<em class="replaceable">
<code>
PATH
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for oci-config-file">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--oci-config-file
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318765392">
</a>
<a class="indexterm" name="idm46045318763904">
</a>
<p>
Alternate path to the Oracle Cloud Infrastructure CLI configuration file. Specify
the location of the configuration file. If your existing
default profile is the correct one, you do not need to
specify this option. However, if you have an existing
configuration file, with multiple profiles or a different
default from the tenancy of the user you want to connect
with, specify this option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_one-database">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_one-database">
<code class="option">
--one-database
</code>
</a>
,
<code class="option">
-o
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for one-database">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--one-database
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318753360">
</a>
<a class="indexterm" name="idm46045318751872">
</a>
<p>
Ignore statements except those that occur while the default
database is the one named on the command line. This option
is rudimentary and should be used with care. Statement
filtering is based only on
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
</code>
</a>
statements.
</p>
<p>
Initially,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
executes statements in
the input because specifying a database
<em class="replaceable">
<code>
db_name
</code>
</em>
on the command line is
equivalent to inserting
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
<em class="replaceable">
<code>
db_name
</code>
</em>
</code>
</a>
at the
beginning of the input. Then, for each
<a class="link" href="use.html" title="15.8.4 USE Statement">
<code class="literal">
USE
</code>
</a>
statement encountered,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
accepts or rejects following
statements depending on whether the database named is the
one on the command line. The content of the statements is
immaterial.
</p>
<p>
Suppose that
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
is invoked to process
this set of statements:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa18514311"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">DELETE</span> <span class="token keyword">FROM</span> db2<span class="token punctuation">.</span>t2<span class="token punctuation">;</span>
<span class="token keyword">USE</span> db2<span class="token punctuation">;</span>
<span class="token keyword">DROP</span> <span class="token keyword">TABLE</span> db1<span class="token punctuation">.</span>t1<span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> db1<span class="token punctuation">.</span>t1 <span class="token punctuation">(</span>i <span class="token datatype">INT</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">USE</span> db1<span class="token punctuation">;</span>
<span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> t1 <span class="token punctuation">(</span>i<span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> db2<span class="token punctuation">.</span>t1 <span class="token punctuation">(</span>j <span class="token datatype">INT</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
</div>
<p>
If the command line is
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql --force --one-database
db1
</strong>
</span>
</a>
,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
handles the input as
follows:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
The
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statement is
executed because the default database is
<code class="literal">
db1
</code>
, even though the statement names
a table in a different database.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement">
<code class="literal">
DROP TABLE
</code>
</a>
and
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statements
are not executed because the default database is not
<code class="literal">
db1
</code>
, even though the statements name
a table in
<code class="literal">
db1
</code>
.
</p>
</li>
<li class="listitem">
<p>
The
<a class="link" href="insert.html" title="15.2.7 INSERT Statement">
<code class="literal">
INSERT
</code>
</a>
and
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statements
are executed because the default database is
<code class="literal">
db1
</code>
, even though the
<a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
<code class="literal">
CREATE TABLE
</code>
</a>
statement
names a table in a different database.
</p>
</li>
</ul>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_pager">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_pager">
<code class="option">
--pager[=
<em class="replaceable">
<code>
command
</code>
</em>
]
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for pager">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--pager[=command]
</code>
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-pager
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318710560">
</a>
<a class="indexterm" name="idm46045318709072">
</a>
<p>
Use the given command for paging query output. If the
command is omitted, the default pager is the value of your
<code class="literal">
PAGER
</code>
environment variable. Valid pagers
are
<span class="command">
<strong>
less
</strong>
</span>
,
<span class="command">
<strong>
more
</strong>
</span>
,
<span class="command">
<strong>
cat [> filename]
</strong>
</span>
, and so forth. This
option works only on Unix and only in interactive mode. To
disable paging, use
<a class="link" href="mysql-command-options.html#option_mysql_pager">
<code class="option">
--skip-pager
</code>
</a>
.
<a class="xref" href="mysql-commands.html" title="6.5.1.2 mysql Client Commands">
Section 6.5.1.2, “mysql Client Commands”
</a>
, discusses output paging
further.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_password">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_password">
<code class="option">
--password[=
<em class="replaceable">
<code>
password
</code>
</em>
]
</code>
</a>
,
<code class="option">
-p[
<em class="replaceable">
<code>
password
</code>
</em>
]
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for password">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--password[=password]
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318691392">
</a>
<a class="indexterm" name="idm46045318689904">
</a>
<p>
The password of the MySQL account used for connecting to the
server. The password value is optional. If not given,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
prompts for one. If given, there
must be
<span class="emphasis">
<em>
no space
</em>
</span>
between
<a class="link" href="mysql-command-options.html#option_mysql_password">
<code class="option">
--password=
</code>
</a>
or
<code class="option">
-p
</code>
and the password following it. If no
password option is specified, the default is to send no
password.
</p>
<p>
Specifying a password on the command line should be
considered insecure. To avoid giving the password on the
command line, use an option file. See
<a class="xref" href="password-security-user.html" title="8.1.2.1 End-User Guidelines for Password Security">
Section 8.1.2.1, “End-User Guidelines for Password Security”
</a>
.
</p>
<p>
To explicitly specify that there is no password and that
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
should not prompt for one, use the
<a class="link" href="mysql-command-options.html#option_mysql_password">
<code class="option">
--skip-password
</code>
</a>
option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_password1">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--password1[=
<em class="replaceable">
<code>
pass_val
</code>
</em>
]
</code>
</a>
</p>
<a class="indexterm" name="idm46045318678112">
</a>
<p>
The password for multifactor authentication factor 1 of the
MySQL account used for connecting to the server. The
password value is optional. If not given,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
prompts for one. If given, there
must be
<span class="emphasis">
<em>
no space
</em>
</span>
between
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--password1=
</code>
</a>
and the password
following it. If no password option is specified, the
default is to send no password.
</p>
<p>
Specifying a password on the command line should be
considered insecure. To avoid giving the password on the
command line, use an option file. See
<a class="xref" href="password-security-user.html" title="8.1.2.1 End-User Guidelines for Password Security">
Section 8.1.2.1, “End-User Guidelines for Password Security”
</a>
.
</p>
<p>
To explicitly specify that there is no password and that
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
should not prompt for one, use the
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--skip-password1
</code>
</a>
option.
</p>
<p>
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--password1
</code>
</a>
and
<a class="link" href="mysql-command-options.html#option_mysql_password">
<code class="option">
--password
</code>
</a>
are synonymous, as
are
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--skip-password1
</code>
</a>
and
<a class="link" href="mysql-command-options.html#option_mysql_password">
<code class="option">
--skip-password
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_password2">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_password2">
<code class="option">
--password2[=
<em class="replaceable">
<code>
pass_val
</code>
</em>
]
</code>
</a>
</p>
<a class="indexterm" name="idm46045318662832">
</a>
<p>
The password for multifactor authentication factor 2 of the
MySQL account used for connecting to the server. The
semantics of this option are similar to the semantics for
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--password1
</code>
</a>
; see the
description of that option for details.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_password3">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_password3">
<code class="option">
--password3[=
<em class="replaceable">
<code>
pass_val
</code>
</em>
]
</code>
</a>
</p>
<a class="indexterm" name="idm46045318657568">
</a>
<p>
The password for multifactor authentication factor 3 of the
MySQL account used for connecting to the server. The
semantics of this option are similar to the semantics for
<a class="link" href="mysql-command-options.html#option_mysql_password1">
<code class="option">
--password1
</code>
</a>
; see the
description of that option for details.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_pipe">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_pipe">
<code class="option">
--pipe
</code>
</a>
,
<code class="option">
-W
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for pipe">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--pipe
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318644784">
</a>
<a class="indexterm" name="idm46045318643296">
</a>
<p>
On Windows, connect to the server using a named pipe. This
option applies only if the server was started with the
<a class="link" href="server-system-variables.html#sysvar_named_pipe">
<code class="literal">
named_pipe
</code>
</a>
system variable
enabled to support named-pipe connections. In addition, the
user making the connection must be a member of the Windows
group specified by the
<a class="link" href="server-system-variables.html#sysvar_named_pipe_full_access_group">
<code class="literal">
named_pipe_full_access_group
</code>
</a>
system variable.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_plugin-authentication-kerberos-client-mode">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_plugin-authentication-kerberos-client-mode">
<code class="option">
--plugin-authentication-kerberos-client-mode=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for plugin-authentication-kerberos-client-mode">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--plugin-authentication-kerberos-client-mode
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
SSPI
</code>
</td>
</tr>
<tr>
<th>
Valid Values
</th>
<td>
<p class="valid-value">
<code class="literal">
GSSAPI
</code>
</p>
<p class="valid-value">
<code class="literal">
SSPI
</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318622064">
</a>
<a class="indexterm" name="idm46045318620544">
</a>
<p>
On Windows, the
<code class="literal">
authentication_kerberos_client
</code>
authentication plugin supports this plugin option. It
provides two possible values that the client user can set at
runtime:
<code class="literal">
SSPI
</code>
and
<code class="literal">
GSSAPI
</code>
.
</p>
<p>
The default value for the client-side plugin option uses
Security Support Provider Interface (SSPI), which is capable
of acquiring credentials from the Windows in-memory cache.
Alternatively, the client user can select a mode that
supports Generic Security Service Application Program
Interface (GSSAPI) through the MIT Kerberos library on
Windows. GSSAPI is capable of acquiring cached credentials
previously generated by using the
<span class="command">
<strong>
kinit
</strong>
</span>
command.
</p>
<p>
For more information, see
<a class="link" href="kerberos-pluggable-authentication.html#kerberos-usage-win-gssapi-client-commands">
Commands
for Windows Clients in GSSAPI Mode
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_plugin-authentication-webauthn-client-preserve-privacy">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_plugin-authentication-webauthn-client-preserve-privacy">
<code class="option">
--plugin-authentication-webauthn-client-preserve-privacy={OFF|ON}
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for plugin-authentication-webauthn-client-preserve-privacy">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--plugin-authentication-webauthn-client-preserve-privacy
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
OFF
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318600672">
</a>
<a class="indexterm" name="idm46045318599136">
</a>
<p>
Determines how assertions are sent to server in case there
is more than one discoverable credential stored for a given
RP ID (a unique name given to the relying-party server,
which is the MySQL server). If the FIDO2 device contains
multiple resident keys for a given RP ID, this option allows
the user to choose a key to be used for assertion. It
provides two possible values that the client user can set.
The default value is
<code class="literal">
OFF
</code>
. If set to
<code class="literal">
OFF
</code>
, the challenge is signed by all
credentials available for a given RP ID and all signatures
are sent to server. If set to
<code class="literal">
ON
</code>
, the
user is prompted to choose the credential to be used for
signature.
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
This option has no effect if the device does not support
the resident-key feature.
</p>
</div>
<p>
For more information, see
<a class="xref" href="webauthn-pluggable-authentication.html" title="8.4.1.11 WebAuthn Pluggable Authentication">
Section 8.4.1.11, “WebAuthn Pluggable Authentication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_plugin-dir">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_plugin-dir">
<code class="option">
--plugin-dir=
<em class="replaceable">
<code>
dir_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for plugin-dir">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--plugin-dir=dir_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Directory name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318582320">
</a>
<a class="indexterm" name="idm46045318580832">
</a>
<p>
The directory in which to look for plugins. Specify this
option if the
<a class="link" href="mysql-command-options.html#option_mysql_default-auth">
<code class="option">
--default-auth
</code>
</a>
option is used to specify an authentication plugin but
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
does not find it. See
<a class="xref" href="pluggable-authentication.html" title="8.2.17 Pluggable Authentication">
Section 8.2.17, “Pluggable Authentication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_port">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_port">
<code class="option">
--port=
<em class="replaceable">
<code>
port_num
</code>
</em>
</code>
</a>
,
<code class="option">
-P
<em class="replaceable">
<code>
port_num
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for port">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--port=port_num
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
3306
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318562720">
</a>
<a class="indexterm" name="idm46045318561232">
</a>
<a class="indexterm" name="idm46045318559744">
</a>
<p>
For TCP/IP connections, the port number to use.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_print-defaults">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_print-defaults">
<code class="option">
--print-defaults
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for print-defaults">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--print-defaults
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318550496">
</a>
<a class="indexterm" name="idm46045318549008">
</a>
<p>
Print the program name and all options that it gets from
option files.
</p>
<p>
For additional information about this and other option-file
options, see
<a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling">
Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_prompt">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_prompt">
<code class="option">
--prompt=
<em class="replaceable">
<code>
format_str
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for prompt">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--prompt=format_str
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
mysql>
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318533424">
</a>
<a class="indexterm" name="idm46045318531936">
</a>
<p>
Set the prompt to the specified format. The default is
<code class="literal">
mysql>
</code>
. The special sequences that the
prompt can contain are described in
<a class="xref" href="mysql-commands.html" title="6.5.1.2 mysql Client Commands">
Section 6.5.1.2, “mysql Client Commands”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_protocol">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_protocol">
<code class="option">
--protocol={TCP|SOCKET|PIPE|MEMORY}
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for protocol">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--protocol=type
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
[see text]
</code>
</td>
</tr>
<tr>
<th>
Valid Values
</th>
<td>
<p class="valid-value">
<code class="literal">
TCP
</code>
</p>
<p class="valid-value">
<code class="literal">
SOCKET
</code>
</p>
<p class="valid-value">
<code class="literal">
PIPE
</code>
</p>
<p class="valid-value">
<code class="literal">
MEMORY
</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318510720">
</a>
<a class="indexterm" name="idm46045318509232">
</a>
<p>
The transport protocol to use for connecting to the server.
It is useful when the other connection parameters normally
result in use of a protocol other than the one you want. For
details on the permissible values, see
<a class="xref" href="transport-protocols.html" title="6.2.7 Connection Transport Protocols">
Section 6.2.7, “Connection Transport Protocols”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_quick">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_quick">
<code class="option">
--quick
</code>
</a>
,
<code class="option">
-q
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for quick">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--quick
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318498368">
</a>
<a class="indexterm" name="idm46045318496880">
</a>
<p>
Do not cache each query result, print each row as it is
received. This may slow down the server if the output is
suspended. With this option,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
does
not use the history file.
</p>
<p>
By default,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
fetches all result rows
before producing any output; while storing these, it
calculates a running maximum column length from the actual
value of each column in succession. When printing the
output, it uses this maximum to format it. When
<code class="option">
--quick
</code>
is specified,
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
does not have the rows for which to
calculate the length before starting, and so uses the
maximum length. In the following example, table
<code class="literal">
t1
</code>
has a single column of type
<a class="link" href="integer-types.html" title="13.1.2 Integer Types (Exact Value) - INTEGER, INT, SMALLINT, TINYINT, MEDIUMINT, BIGINT">
<code class="literal">
BIGINT
</code>
</a>
and containing 4 rows.
The default output is 9 characters wide; this width is equal
the maximum number of characters in any of the column values
in the rows returned (5), plus 2 characters each for the
spaces used as padding and the
<code class="literal">
|
</code>
characters used as column delimiters). The output when using
the
<code class="option">
--quick
</code>
option is 25 characters wide;
this is equal to the number of characters needed to
represent
<code class="literal">
-9223372036854775808
</code>
, which is
the longest possible value that can be stored in a (signed)
<code class="literal">
BIGINT
</code>
column, or 19 characters, plus the
4 characters used for padding and column delimiters. The
difference can be seen here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa93620902"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-t</span> test <span class="token property">-e</span> <span class="token atrule">"SELECT * FROM t1"</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 100 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 1000 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 10000 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">--quick</span> <span class="token property">-t</span> test <span class="token property">-e</span> <span class="token atrule">"SELECT * FROM t1"</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> 100 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 1000 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 10000 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_raw">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_raw">
<code class="option">
--raw
</code>
</a>
,
<code class="option">
-r
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for raw">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--raw
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318473728">
</a>
<a class="indexterm" name="idm46045318472240">
</a>
<p>
For tabular output, the
<span class="quote">
“
<span class="quote">
boxing
</span>
”
</span>
around columns
enables one column value to be distinguished from another.
For nontabular output (such as is produced in batch mode or
when the
<a class="link" href="mysql-command-options.html#option_mysql_batch">
<code class="option">
--batch
</code>
</a>
or
<a class="link" href="mysql-command-options.html#option_mysql_silent">
<code class="option">
--silent
</code>
</a>
option is given),
special characters are escaped in the output so they can be
identified easily. Newline, tab,
<code class="literal">
NUL
</code>
, and
backslash are written as
<code class="literal">
\n
</code>
,
<code class="literal">
\t
</code>
,
<code class="literal">
\0
</code>
, and
<code class="literal">
\\
</code>
. The
<a class="link" href="mysql-command-options.html#option_mysql_raw">
<code class="option">
--raw
</code>
</a>
option disables this
character escaping.
</p>
<p>
The following example demonstrates tabular versus nontabular
output and the use of raw mode to disable escaping:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92588213"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token operator">%</span> mysql
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">92</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> CHAR(92) <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> \ <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token operator">%</span> mysql <span class="token operator">-</span>s
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">92</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">92</span><span class="token punctuation">)</span>
\\
<span class="token operator">%</span> mysql <span class="token operator">-</span>s <span class="token operator">-</span>r
<span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">92</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token datatype">CHAR</span><span class="token punctuation">(</span><span class="token number">92</span><span class="token punctuation">)</span>
\</code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_reconnect">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_reconnect">
<code class="option">
--reconnect
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for reconnect">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--reconnect
</code>
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-reconnect
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318449120">
</a>
<a class="indexterm" name="idm46045318447632">
</a>
<p>
If the connection to the server is lost, automatically try
to reconnect. A single reconnect attempt is made each time
the connection is lost. To suppress reconnection behavior,
use
<a class="link" href="mysql-command-options.html#option_mysql_reconnect">
<code class="option">
--skip-reconnect
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_register-factor">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_register-factor">
<code class="option">
--register-factor=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for register-factor">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--register-factor=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318434496">
</a>
<a class="indexterm" name="idm46045318433008">
</a>
<p>
The factor or factors for which FIDO/FIDO2 device
registration must be performed before WebAuthn device-based
authentication can be used. This option value must be a
single value, or two values separated by commas. Each value
must be 2 or 3, so the permitted option values are
<code class="literal">
'2'
</code>
,
<code class="literal">
'3'
</code>
,
<code class="literal">
'2,3'
</code>
and
<code class="literal">
'3,2'
</code>
.
</p>
<p>
For example, an account that requires registration for a
third authentication factor invokes the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client as follows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa26471070"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">user_name</em></span> <span class="token constant">--register-factor</span><span class="token attr-value"><span class="token punctuation">=</span>3</span></code></pre>
</div>
<p>
An account that requires registration for second and third
authentication factors invokes the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
client as follows:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa53474"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">user_name</em></span> <span class="token constant">--register-factor</span><span class="token attr-value"><span class="token punctuation">=</span>2,3</span></code></pre>
</div>
<p>
If registration is successful, a connection is established.
If there is an authentication factor with a pending
registration, a connection is placed into pending
registration mode when attempting to connect to the server.
In this case, disconnect and reconnect with the correct
<a class="link" href="mysql-command-options.html#option_mysql_register-factor">
<code class="option">
--register-factor
</code>
</a>
value to
complete the registration.
</p>
<p>
Registration is a two-step process comprising
<span class="emphasis">
<em>
initiate registration
</em>
</span>
and
<span class="emphasis">
<em>
finish registration
</em>
</span>
steps. The initiate
registration step executes this statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa73890961"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">USER</span> <span class="token keyword"><em class="replaceable">user</em></span> <em class="replaceable">factor</em> INITIATE REGISTRATION</code></pre>
</div>
<p>
The statement returns a result set containing a 32 byte
challenge, the user name, and the relying party ID (see
<a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_webauthn_rp_id">
<code class="literal">
authentication_webauthn_rp_id
</code>
</a>
).
</p>
<p>
The finish registration step executes this statement:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa69137336"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">USER</span> <span class="token keyword"><em class="replaceable">user</em></span> <em class="replaceable">factor</em> FINISH REGISTRATION <span class="token keyword">SET</span> CHALLENGE_RESPONSE <span class="token keyword">AS</span> <span class="token string">'<em class="replaceable">auth_string</em>'</span></code></pre>
</div>
<p>
The statement completes the registration and sends the
following information to the server as part of the
<em class="replaceable">
<code>
auth_string
</code>
</em>
: authenticator data,
an optional attestation certificate in X.509 format, and a
signature.
</p>
<p>
The initiate and registration steps must be performed in a
single connection, as the challenge received by the client
during the initiate step is saved to the client connection
handler. Registration would fail if the registration step
was performed by a different connection. The
<a class="link" href="mysql-command-options.html#option_mysql_register-factor">
<code class="option">
--register-factor
</code>
</a>
option
executes both the initiate and registration steps, which
avoids the failure scenario described above and prevents
having to execute the
<a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement">
<code class="literal">
ALTER
USER
</code>
</a>
initiate and registration statements
manually.
</p>
<p>
The
<a class="link" href="mysql-command-options.html#option_mysql_register-factor">
<code class="option">
--register-factor
</code>
</a>
option
is only available for the
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
and
MySQL Shell clients. Other MySQL client programs do not
support it.
</p>
<p>
For related information, see
<a class="xref" href="webauthn-pluggable-authentication.html#webauthn-pluggable-authentication-usage" title="Using WebAuthn Authentication">
Using WebAuthn Authentication
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_safe-updates">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--safe-updates
</code>
</a>
,
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--i-am-a-dummy
</code>
</a>
,
<code class="option">
-U
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for safe-updates">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<p class="valid-value">
<code class="literal">
--safe-updates
</code>
</p>
<p class="valid-value">
<code class="literal">
--i-am-a-dummy
</code>
</p>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
FALSE
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318388624">
</a>
<a class="indexterm" name="idm46045318387136">
</a>
<a class="indexterm" name="idm46045318385648">
</a>
<a class="indexterm" name="idm46045318384160">
</a>
<p>
If this option is enabled,
<a class="link" href="update.html" title="15.2.17 UPDATE Statement">
<code class="literal">
UPDATE
</code>
</a>
and
<a class="link" href="delete.html" title="15.2.2 DELETE Statement">
<code class="literal">
DELETE
</code>
</a>
statements that do not
use a key in the
<code class="literal">
WHERE
</code>
clause or a
<code class="literal">
LIMIT
</code>
clause produce an error. In
addition, restrictions are placed on
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements that
produce (or are estimated to produce) very large result
sets. If you have set this option in an option file, you can
use
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--skip-safe-updates
</code>
</a>
on the command line to override it. For more information
about this option, see
<a class="xref" href="mysql-tips.html#safe-updates" title="Using Safe-Updates Mode (--safe-updates)">
Using Safe-Updates Mode (--safe-updates)
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_select-limit">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_select-limit">
<code class="option">
--select-limit=
<em class="replaceable">
<code>
value
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for select-limit">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--select-limit=value
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Numeric
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
1000
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318362352">
</a>
<a class="indexterm" name="idm46045318360864">
</a>
<p>
The automatic limit for
<a class="link" href="select.html" title="15.2.13 SELECT Statement">
<code class="literal">
SELECT
</code>
</a>
statements when using
<a class="link" href="mysql-command-options.html#option_mysql_safe-updates">
<code class="option">
--safe-updates
</code>
</a>
. (Default value
is 1,000.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_server-public-key-path">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_server-public-key-path">
<code class="option">
--server-public-key-path=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for server-public-key-path">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--server-public-key-path=file_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
File name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318346576">
</a>
<a class="indexterm" name="idm46045318345072">
</a>
<p>
The path name to a file in PEM format containing a
client-side copy of the public key required by the server
for RSA key pair-based password exchange. This option
applies to clients that authenticate with the
<code class="literal">
sha256_password
</code>
(deprecated) or
<code class="literal">
caching_sha2_password
</code>
authentication
plugin. This option is ignored for accounts that do not
authenticate with one of those plugins. It is also ignored
if RSA-based password exchange is not used, as is the case
when the client connects to the server using a secure
connection.
</p>
<p>
If
<a class="link" href="mysql-command-options.html#option_mysql_server-public-key-path">
<code class="option">
--server-public-key-path=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
is given and specifies a valid public key file, it takes
precedence over
<a class="link" href="mysql-command-options.html#option_mysql_get-server-public-key">
<code class="option">
--get-server-public-key
</code>
</a>
.
</p>
<p>
For
<code class="literal">
sha256_password
</code>
(deprecated), this
option applies only if MySQL was built using OpenSSL.
</p>
<p>
For information about the
<code class="literal">
sha256_password
</code>
and
<code class="literal">
caching_sha2_password
</code>
plugins, see
<a class="xref" href="sha256-pluggable-authentication.html" title="8.4.1.3 SHA-256 Pluggable Authentication">
Section 8.4.1.3, “SHA-256 Pluggable Authentication”
</a>
, and
<a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication">
Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_shared-memory-base-name">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_shared-memory-base-name">
<code class="option">
--shared-memory-base-name=
<em class="replaceable">
<code>
name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for shared-memory-base-name">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--shared-memory-base-name=name
</code>
</td>
</tr>
<tr>
<th>
Platform Specific
</th>
<td>
Windows
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318323728">
</a>
<a class="indexterm" name="idm46045318322224">
</a>
<p>
On Windows, the shared-memory name to use for connections
made using shared memory to a local server. The default
value is
<code class="literal">
MYSQL
</code>
. The shared-memory name is
case-sensitive.
</p>
<p>
This option applies only if the server was started with the
<a class="link" href="server-system-variables.html#sysvar_shared_memory">
<code class="literal">
shared_memory
</code>
</a>
system
variable enabled to support shared-memory connections.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_show-warnings">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_show-warnings">
<code class="option">
--show-warnings
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for show-warnings">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--show-warnings
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318309904">
</a>
<a class="indexterm" name="idm46045318308416">
</a>
<p>
Cause warnings to be shown after each statement if there are
any. This option applies to interactive and batch mode.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_sigint-ignore">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_sigint-ignore">
<code class="option">
--sigint-ignore
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for sigint-ignore">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--sigint-ignore
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318298656">
</a>
<a class="indexterm" name="idm46045318297168">
</a>
<p>
Ignore
<code class="literal">
SIGINT
</code>
signals (typically the
result of typing
<span class="keycap">
<strong>
Control+C
</strong>
</span>
).
</p>
<p>
Without this option, typing
<span class="keycap">
<strong>
Control+C
</strong>
</span>
interrupts the current statement if there is one, or cancels
any partial input line otherwise.
</p>
<a class="indexterm" name="idm46045318292512">
</a>
<a class="indexterm" name="idm46045318291024">
</a>
<a class="indexterm" name="idm46045318289536">
</a>
</li>
<li class="listitem">
<p>
<a name="option_mysql_silent">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_silent">
<code class="option">
--silent
</code>
</a>
,
<code class="option">
-s
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for silent">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--silent
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318279984">
</a>
<a class="indexterm" name="idm46045318278496">
</a>
<p>
Silent mode. Produce less output. This option can be given
multiple times to produce less and less output.
</p>
<p>
This option results in nontabular output format and escaping
of special characters. Escaping may be disabled by using raw
mode; see the description for the
<a class="link" href="mysql-command-options.html#option_mysql_raw">
<code class="option">
--raw
</code>
</a>
option.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_skip-column-names">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_skip-column-names">
<code class="option">
--skip-column-names
</code>
</a>
,
<code class="option">
-N
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for skip-column-names">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--skip-column-names
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318266720">
</a>
<a class="indexterm" name="idm46045318265216">
</a>
<p>
Do not write column names in results. Use of this option
causes the output to be right-aligned, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa97922444"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">echo</span> <span class="token atrule">"SELECT * FROM t1"</span> | mysql <span class="token property">-t</span> test
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> c1 <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a,c,d <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> c <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token prompt">$> </span><span class="token command">echo</span> <span class="token atrule">"SELECT * FROM t1"</span> | <span class="token punctuation">.</span>/mysql <span class="token property">-uroot</span> <span class="token property">-Nt</span> test
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> a,c,d <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> c <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_skip-line-numbers">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_skip-line-numbers">
<code class="option">
--skip-line-numbers
</code>
</a>
,
<code class="option">
-L
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for skip-line-numbers">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--skip-line-numbers
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318252448">
</a>
<a class="indexterm" name="idm46045318250944">
</a>
<p>
Do not write line numbers for errors. Useful when you want
to compare result files that include error messages.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_skip-system-command">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_skip-system-command">
<code class="option">
--skip-system-command
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for skip-system-command">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--skip-system-command
</code>
</td>
</tr>
<tr>
<th>
Introduced
</th>
<td>
8.4.3
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318239136">
</a>
<a class="indexterm" name="idm46045318237632">
</a>
<p>
Disables the
<code class="literal">
system
</code>
(
<code class="literal">
\!
</code>
) command. Equivalent to
<a class="link" href="mysql-command-options.html#option_mysql_system-command">
<code class="option">
--system-command=OFF
</code>
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_socket">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_socket">
<code class="option">
--socket=
<em class="replaceable">
<code>
path
</code>
</em>
</code>
</a>
,
<code class="option">
-S
<em class="replaceable">
<code>
path
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for socket">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--socket={file_name|pipe_name}
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318222544">
</a>
<a class="indexterm" name="idm46045318221056">
</a>
<p>
For connections to
<code class="literal">
localhost
</code>
, the Unix
socket file to use, or, on Windows, the name of the named
pipe to use.
</p>
<p>
On Windows, this option applies only if the server was
started with the
<a class="link" href="server-system-variables.html#sysvar_named_pipe">
<code class="literal">
named_pipe
</code>
</a>
system variable enabled to support named-pipe connections.
In addition, the user making the connection must be a member
of the Windows group specified by the
<a class="link" href="server-system-variables.html#sysvar_named_pipe_full_access_group">
<code class="literal">
named_pipe_full_access_group
</code>
</a>
system variable.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_ssl">
</a>
<code class="option">
--ssl*
</code>
</p>
<a class="indexterm" name="idm46045318213472">
</a>
<a class="indexterm" name="idm46045318211984">
</a>
<p>
Options that begin with
<code class="option">
--ssl
</code>
specify
whether to connect to the server using encryption and
indicate where to find SSL keys and certificates. See
<a class="xref" href="connection-options.html#encrypted-connection-options" title="Command Options for Encrypted Connections">
Command Options for Encrypted Connections
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_ssl-fips-mode">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
<code class="option">
--ssl-fips-mode={OFF|ON|STRICT}
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for ssl-fips-mode">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--ssl-fips-mode={OFF|ON|STRICT}
</code>
</td>
</tr>
<tr>
<th>
Deprecated
</th>
<td>
Yes
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Enumeration
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
OFF
</code>
</td>
</tr>
<tr>
<th>
Valid Values
</th>
<td>
<p class="valid-value">
<code class="literal">
OFF
</code>
</p>
<p class="valid-value">
<code class="literal">
ON
</code>
</p>
<p class="valid-value">
<code class="literal">
STRICT
</code>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318189840">
</a>
<a class="indexterm" name="idm46045318188352">
</a>
<p>
Controls whether to enable FIPS mode on the client side. The
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
<code class="option">
--ssl-fips-mode
</code>
</a>
option differs
from other
<code class="option">
--ssl-
<em class="replaceable">
<code>
xxx
</code>
</em>
</code>
options in that it is not used to establish encrypted
connections, but rather to affect which cryptographic
operations to permit. See
<a class="xref" href="fips-mode.html" title="8.8 FIPS Support">
Section 8.8, “FIPS Support”
</a>
.
</p>
<p>
These
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
<code class="option">
--ssl-fips-mode
</code>
</a>
values
are permitted:
</p>
<div class="itemizedlist">
<ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
<p>
<code class="literal">
OFF
</code>
: Disable FIPS mode.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
ON
</code>
: Enable FIPS mode.
</p>
</li>
<li class="listitem">
<p>
<code class="literal">
STRICT
</code>
: Enable
<span class="quote">
“
<span class="quote">
strict
</span>
”
</span>
FIPS mode.
</p>
</li>
</ul>
</div>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<div class="admon-title">
Note
</div>
<p>
If the OpenSSL FIPS Object Module is not available, the
only permitted value for
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
<code class="option">
--ssl-fips-mode
</code>
</a>
is
<code class="literal">
OFF
</code>
. In this case, setting
<a class="link" href="mysql-command-options.html#option_mysql_ssl-fips-mode">
<code class="option">
--ssl-fips-mode
</code>
</a>
to
<code class="literal">
ON
</code>
or
<code class="literal">
STRICT
</code>
causes
the client to produce a warning at startup and to operate
in non-FIPS mode.
</p>
</div>
<p>
This option is deprecated. Expect it to be removed in a
future version of MySQL.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_syslog">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_syslog">
<code class="option">
--syslog
</code>
</a>
,
<code class="option">
-j
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for syslog">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--syslog
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318163440">
</a>
<a class="indexterm" name="idm46045318161952">
</a>
<p>
This option causes
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
to send
interactive statements to the system logging facility. On
Unix, this is
<code class="literal">
syslog
</code>
; on Windows, it is
the Windows Event Log. The destination where logged messages
appear is system dependent. On Linux, the destination is
often the
<code class="filename">
/var/log/messages
</code>
file.
</p>
<p>
Here is a sample of output generated on Linux by using
<code class="option">
--syslog
</code>
. This output is formatted for
readability; each logged message actually takes a single
line.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-none"><div class="docs-select-all right" id="sa14381557"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">Mar 7 12:39:25 myhost MysqlClient[20824]:
SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,
DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'
Mar 7 12:39:28 myhost MysqlClient[20824]:
SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,
DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'</code></pre>
</div>
<p>
For more information, see
<a class="xref" href="mysql-logging.html" title="6.5.1.3 mysql Client Logging">
Section 6.5.1.3, “mysql Client Logging”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_system-command">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_system-command">
<code class="option">
--system-command[={ON|OFF}]
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for system-command">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--system-command[={ON|OFF}]
</code>
</td>
</tr>
<tr>
<th>
Introduced
</th>
<td>
8.4.3
</td>
</tr>
<tr>
<th>
Disabled by
</th>
<td>
<code class="literal">
skip-system-command
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
ON
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318136976">
</a>
<a class="indexterm" name="idm46045318135488">
</a>
<p>
Enable or disable the
<code class="literal">
system
</code>
(
<code class="literal">
\!
</code>
) command. When this option is
disabled, either by
<code class="option">
--system-command=OFF
</code>
or
by
<a class="link" href="mysql-command-options.html#option_mysql_skip-system-command">
<code class="option">
--skip-system-command
</code>
</a>
, the
<code class="literal">
system
</code>
command is rejected with an error.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_table">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_table">
<code class="option">
--table
</code>
</a>
,
<code class="option">
-t
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for table">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--table
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318121856">
</a>
<a class="indexterm" name="idm46045318120368">
</a>
<p>
Display output in table format. This is the default for
interactive use, but can be used to produce table output in
batch mode.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_tee">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_tee">
<code class="option">
--tee=
<em class="replaceable">
<code>
file_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for tee">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--tee=file_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
File name
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318108336">
</a>
<a class="indexterm" name="idm46045318106848">
</a>
<p>
Append a copy of output to the given file. This option works
only in interactive mode.
<a class="xref" href="mysql-commands.html" title="6.5.1.2 mysql Client Commands">
Section 6.5.1.2, “mysql Client Commands”
</a>
,
discusses tee files further.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_tls-ciphersuites">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_tls-ciphersuites">
<code class="option">
--tls-ciphersuites=
<em class="replaceable">
<code>
ciphersuite_list
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for tls-ciphersuites">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--tls-ciphersuites=ciphersuite_list
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318094080">
</a>
<a class="indexterm" name="idm46045318092592">
</a>
<p>
The permissible ciphersuites for encrypted connections that
use TLSv1.3. The value is a list of one or more
colon-separated ciphersuite names. The ciphersuites that can
be named for this option depend on the SSL library used to
compile MySQL. For details, see
<a class="xref" href="encrypted-connection-protocols-ciphers.html" title="8.3.2 Encrypted Connection TLS Protocols and Ciphers">
Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_tls-sni-servername">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_tls-sni-servername">
<code class="option">
--tls-sni-servername=
<em class="replaceable">
<code>
server_name
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for tls-sni-servername">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--tls-sni-servername=server_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318079600">
</a>
<a class="indexterm" name="idm46045318078096">
</a>
<p>
When specified, the name is passed to the
<code class="literal">
libmysqlclient
</code>
C API library using the
<code class="literal">
MYSQL_OPT_TLS_SNI_SERVERNAME
</code>
option of
<a class="ulink" href="/doc/c-api/8.4/en/mysql-options.html" target="_top">
<code class="literal">
mysql_options()
</code>
</a>
. The server
name is not case-sensitive. To show which server name the
client specified for the current session, if any, check the
<a class="link" href="server-status-variables.html#statvar_Tls_sni_server_name">
<code class="literal">
Tls_sni_server_name
</code>
</a>
status
variable.
</p>
<p>
Server Name Indication (SNI) is an extension to the TLS
protocol (OpenSSL must be compiled using TLS extensions for
this option to function). The MySQL implementation of SNI
represents the client-side only.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_tls-version">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_tls-version">
<code class="option">
--tls-version=
<em class="replaceable">
<code>
protocol_list
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for tls-version">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--tls-version=protocol_list
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<p class="valid-value">
<code class="literal">
TLSv1,TLSv1.1,TLSv1.2,TLSv1.3
</code>
(OpenSSL 1.1.1 or higher)
</p>
<p class="valid-value">
<code class="literal">
TLSv1,TLSv1.1,TLSv1.2
</code>
(otherwise)
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318057152">
</a>
<a class="indexterm" name="idm46045318055664">
</a>
<p>
The permissible TLS protocols for encrypted connections. The
value is a list of one or more comma-separated protocol
names. The protocols that can be named for this option
depend on the SSL library used to compile MySQL. For
details, see
<a class="xref" href="encrypted-connection-protocols-ciphers.html" title="8.3.2 Encrypted Connection TLS Protocols and Ciphers">
Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_unbuffered">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_unbuffered">
<code class="option">
--unbuffered
</code>
</a>
,
<code class="option">
-n
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for unbuffered">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--unbuffered
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318044656">
</a>
<a class="indexterm" name="idm46045318043168">
</a>
<p>
Flush the buffer after each query.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_user">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_user">
<code class="option">
--user=
<em class="replaceable">
<code>
user_name
</code>
</em>
</code>
</a>
,
<code class="option">
-u
<em class="replaceable">
<code>
user_name
</code>
</em>
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for user">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--user=user_name
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
String
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318030544">
</a>
<a class="indexterm" name="idm46045318029056">
</a>
<p>
The user name of the MySQL account to use for connecting to
the server.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_verbose">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_verbose">
<code class="option">
--verbose
</code>
</a>
,
<code class="option">
-v
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for verbose">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--verbose
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318019040">
</a>
<a class="indexterm" name="idm46045318017552">
</a>
<p>
Verbose mode. Produce more output about what the program
does. This option can be given multiple times to produce
more and more output. (For example,
<code class="option">
-v -v
-v
</code>
produces table output format even in batch
mode.)
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_version">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_version">
<code class="option">
--version
</code>
</a>
,
<code class="option">
-V
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for version">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--version
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045318006944">
</a>
<a class="indexterm" name="idm46045318005456">
</a>
<p>
Display version information and exit.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_vertical">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_vertical">
<code class="option">
--vertical
</code>
</a>
,
<code class="option">
-E
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for vertical">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--vertical
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045317995456">
</a>
<a class="indexterm" name="idm46045317993968">
</a>
<p>
Print query output rows vertically (one line per column
value). Without this option, you can specify vertical output
for individual statements by terminating them with
<code class="literal">
\G
</code>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_wait">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_wait">
<code class="option">
--wait
</code>
</a>
,
<code class="option">
-w
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for wait">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--wait
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045317983104">
</a>
<a class="indexterm" name="idm46045317981616">
</a>
<p>
If the connection cannot be established, wait and retry
instead of aborting.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_xml">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_xml">
<code class="option">
--xml
</code>
</a>
,
<code class="option">
-X
</code>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for xml">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--xml
</code>
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045317971552">
</a>
<a class="indexterm" name="idm46045317970064">
</a>
<p>
Produce XML output.
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting one-line language-xml"><div class="docs-select-all right" id="sa50428682"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-xml"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>field</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span><em class="replaceable">column_name</em><span class="token punctuation">"</span></span><span class="token punctuation">></span></span>NULL<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>field</span><span class="token punctuation">></span></span></code></pre>
</div>
<p>
The output when
<a class="link" href="mysql-command-options.html#option_mysql_xml">
<code class="option">
--xml
</code>
</a>
is used
with
<a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client">
<span class="command">
<strong>
mysql
</strong>
</span>
</a>
matches that of
<a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
<span class="command">
<strong>
mysqldump
</strong>
</span>
</a>
<a class="link" href="mysqldump.html#option_mysqldump_xml">
<code class="option">
--xml
</code>
</a>
. See
<a class="xref" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program">
Section 6.5.4, “mysqldump — A Database Backup Program”
</a>
, for details.
</p>
<p>
The XML output also uses an XML namespace, as shown here:
</p>
<div class="copytoclipboard-wrapper">
<pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa33505153"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">--xml</span> <span class="token property">-uroot</span> <span class="token property">-e</span> <span class="token atrule">"SHOW VARIABLES LIKE 'version%'"</span>
<?xml version=<span class="token atrule">"1.0"</span>?>
<resultset statement=<span class="token atrule">"SHOW VARIABLES LIKE 'version%'"</span> xmlns<span class="token punctuation">:</span>xsi=<span class="token atrule">"http://www.w3.org/2001/XMLSchema-instance"</span>>
<row>
<field name=<span class="token atrule">"Variable_name"</span>>version</field>
<field name=<span class="token atrule">"Value"</span>>5<span class="token punctuation">.</span>0<span class="token punctuation">.</span>40-debug</field>
</row>
<row>
<field name=<span class="token atrule">"Variable_name"</span>>version_comment</field>
<field name=<span class="token atrule">"Value"</span>>Source distribution</field>
</row>
<row>
<field name=<span class="token atrule">"Variable_name"</span>>version_compile_machine</field>
<field name=<span class="token atrule">"Value"</span>>i686</field>
</row>
<row>
<field name=<span class="token atrule">"Variable_name"</span>>version_compile_os</field>
<field name=<span class="token atrule">"Value"</span>>suse-linux-gnu</field>
</row>
</resultset></code></pre>
</div>
</li>
<li class="listitem">
<p>
<a name="option_mysql_zstd-compression-level">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_zstd-compression-level">
<code class="option">
--zstd-compression-level=
<em class="replaceable">
<code>
level
</code>
</em>
</code>
</a>
</p>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for zstd-compression-level">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--zstd-compression-level=#
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Integer
</td>
</tr>
</tbody>
</table>
</div>
<a class="indexterm" name="idm46045317948192">
</a>
<a class="indexterm" name="idm46045317946688">
</a>
<p>
The compression level to use for connections to the server
that use the
<code class="literal">
zstd
</code>
compression algorithm.
The permitted levels are from 1 to 22, with larger values
indicating increasing levels of compression. The default
<code class="literal">
zstd
</code>
compression level is 3. The
compression level setting has no effect on connections that
do not use
<code class="literal">
zstd
</code>
compression.
</p>
<p>
For more information, see
<a class="xref" href="connection-compression-control.html" title="6.2.8 Connection Compression Control">
Section 6.2.8, “Connection Compression Control”
</a>
.
</p>
</li>
<li class="listitem">
<p>
<a name="option_mysql_telemetry_client">
</a>
<a class="link" href="mysql-command-options.html#option_mysql_telemetry_client">
<code class="option">
telemetry_client
</code>
</a>
</p>
<a class="indexterm" name="idm46045317938848">
</a>
<a class="indexterm" name="idm46045317937360">
</a>
<div class="informaltable">
<table frame="box" rules="all" summary="Properties for telemetry_client">
<colgroup>
<col style="width: 30%"/>
<col style="width: 70%"/>
</colgroup>
<tbody>
<tr>
<th>
Command-Line Format
</th>
<td>
<code class="literal">
--telemetry_client
</code>
</td>
</tr>
<tr>
<th>
Type
</th>
<td>
Boolean
</td>
</tr>
<tr>
<th>
Default Value
</th>
<td>
<code class="literal">
OFF
</code>
</td>
</tr>
</tbody>
</table>
</div>
<p>
Enables the telemetry client plugin (Linux only).
</p>
<p>
For more information, see
<a class="xref" href="telemetry.html" title="Chapter 35 Telemetry">
Chapter 35,
<i>
Telemetry
</i>
</a>
.
</p>
</li>
</ul>
</div>
</div>
<br/>
</div>
|
Subsets and Splits