diff --git "a/pgsql-performance.200304" "b/pgsql-performance.200304" new file mode 100644--- /dev/null +++ "b/pgsql-performance.200304" @@ -0,0 +1,25187 @@ +From pgsql-performance-owner@postgresql.org Tue Apr 1 07:23:33 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C83FF475F1B + for ; + Tue, 1 Apr 2003 07:23:30 -0500 (EST) +Received: from spirit.aldeiadigital.com.br + (iplus-fac-213-137.xdsl-fixo.ctbcnetsuper.com.br [200.225.213.137]) + by postgresql.org (Postfix) with ESMTP id AE3B8475AF8 + for ; + Tue, 1 Apr 2003 07:23:28 -0500 (EST) +Received: from aldeiadigital.com.br (localhost.localdomain [127.0.0.1]) + by spirit.aldeiadigital.com.br (8.11.6/8.11.6) with SMTP id + h31CNfa13948 + for ; Tue, 1 Apr 2003 09:23:42 -0300 +Received: from 200.170.156.137 (proxying for 126.0.0.10) + (SquirrelMail authenticated user alepaes) + by webmail.ad2.com.br with HTTP; Tue, 1 Apr 2003 09:23:42 -0300 (BRT) +Message-ID: <39940.200.170.156.137.1049199822.squirrel@webmail.ad2.com.br> +Date: Tue, 1 Apr 2003 09:23:42 -0300 (BRT) +Subject: Re: 30-70 seconds query... +From: "alexandre :: aldeia digital" +To: +In-Reply-To: <25846.1049151512@sss.pgh.pa.us> +References: <10846.200.225.202.15.1049145207.squirrel@webmail.ad2.com.br> + <25610.1049149040@sss.pgh.pa.us> <25846.1049151512@sss.pgh.pa.us> +X-Priority: 3 +Importance: Normal +X-MSMail-Priority: Normal +X-Mailer: SquirrelMail (version 1.2.7) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +X-Virus-Scanned: by amavisd-milter (http://amavis.org/) +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-25.1 required=5.0 + tests=BAYES_10,IN_REP_TO,MISSING_MIMEOLE,MISSING_OUTLOOK_NAME, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/1 +X-Sequence-Number: 1507 + +Tom, + +I will try the current snapshot and I will report in the list. + +Thanks to Tomasz Myrta too for the help. + + +Alexandre + + +> I said: +>> PG 7.4 will be better prepared to handle this sort of query, but I +>> don't think it will realize that the T1/T2 left join could be reduced +>> to a plain join given these conditions +> +> I take that back --- actually, the algorithm used in CVS tip *does* +> deduce that all these left joins can be plain joins. +> +> Don't suppose you'd like to experiment with a current snapshot to see +> how well it does for you? +> +> regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 12:25:40 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 10E0C47621C + for ; + Tue, 1 Apr 2003 12:25:39 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id A9CF0476178 + for ; + Tue, 1 Apr 2003 12:25:34 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h31HFXr08210; + Tue, 1 Apr 2003 12:15:33 -0500 +Message-ID: <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Shankar K" , + +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Tue, 1 Apr 2003 12:33:15 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-16.9 required=5.0 + tests=BAYES_20,MAILTO_TO_SPAM_ADDR,ORIGINAL_MESSAGE, + QUOTED_EMAIL_TEXT,RCVD_IN_NJABL,REFERENCES, X_NJABL_OPEN_PROXY + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/2 +X-Sequence-Number: 1508 + +What is the URL of that article? I understood that ext2 was faster with PG +and so I went to a lot of trouble of creating an ext2 partition just for PG +and gave up the journalling to do that. Something about double effort since +PG already does a lot of that. + +Bruce, is there a final determination of which is faster/safer? + + Jeff + +----- Original Message ----- +From: "Shankar K" +To: +Sent: Monday, March 31, 2003 3:55 PM +Subject: [PERFORM] ext3 filesystem / linux 7.3 + + +> hi there, +> +> I was reading bruce's 'postgresql hardware performance +> tuning' article and he has suggested ext3 filesystem +> with data mode = writeback for high performance. +> +> I would really appreciate if anyone could share your +> experiences with ext3 from a production stand point or +> any other suggestions for best read/write performance. +> +> Our applications is an hybrid of heavy inserts/updates +> and DSS queries. +> +> version - postgres 7.3.2 +> hardware - raid 5 (5 x 73 g hardware raid), 4g ram, 2 +> * 2.8 GHz cpu, redhat 7.3 +> +> Note : we don't have the luxury of raid 1+0 (dedicated +> disks) for xlog and clog files to start with but may +> be down the line we might look into those options, but +> for now i've planned on having them on local drives +> rather than raid 5. +> +> thanks for any inputs, +> Shankar +> +> +> +> +> +> +> __________________________________________________ +> Do you Yahoo!? +> Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop! +> http://platinum.yahoo.com +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 12:39:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C8037476348 + for ; + Tue, 1 Apr 2003 12:39:12 -0500 (EST) +Received: from web21101.mail.yahoo.com (web21101.mail.yahoo.com + [216.136.227.103]) + by postgresql.org (Postfix) with SMTP id 9CA2C476304 + for ; + Tue, 1 Apr 2003 12:39:11 -0500 (EST) +Message-ID: <20030401173917.19476.qmail@web21101.mail.yahoo.com> +Received: from [208.253.218.33] by web21101.mail.yahoo.com via HTTP; + Tue, 01 Apr 2003 09:39:17 PST +Date: Tue, 1 Apr 2003 09:39:17 -0800 (PST) +From: Shankar K +Subject: Re: ext3 filesystem / linux 7.3 +To: pgsql-performance@postgresql.org +Cc: "Jeffrey D. Brower" +In-Reply-To: <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-8.5 required=5.0 + tests=BAYES_01,FROM_ENDS_IN_NUMS,IN_REP_TO,MAILTO_TO_SPAM_ADDR + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/3 +X-Sequence-Number: 1509 + +hi jeff, + +go to +http://www.ca.postgresql.org/docs/momjian/hw_performance/ +under 'filesystems' slide. + +snip + +File system choice is particularly difficult on Linux +because there are so many file system choices, and +none of them are optimal: ext2 is not entirely +crash-safe, ext3, XFS, and JFS are journal-based, and +Reiser is optimized for small files and does +journalling. The journalling file systems can be +significantly slower than ext2 but when crash recovery +is required, ext2 isn't an option. If ext2 must be +used, mount it with sync enabled. Some people +recommend XFS or an ext3 filesystem mounted with +data=writeback. + +/snip + +--- "Jeffrey D. Brower" wrote: +> What is the URL of that article? I understood that +> ext2 was faster with PG +> and so I went to a lot of trouble of creating an +> ext2 partition just for PG +> and gave up the journalling to do that. Something +> about double effort since +> PG already does a lot of that. +> +> Bruce, is there a final determination of which is +> faster/safer? +> +> Jeff +> +> ----- Original Message ----- +> From: "Shankar K" +> To: +> Sent: Monday, March 31, 2003 3:55 PM +> Subject: [PERFORM] ext3 filesystem / linux 7.3 +> +> +> > hi there, +> > +> > I was reading bruce's 'postgresql hardware +> performance +> > tuning' article and he has suggested ext3 +> filesystem +> > with data mode = writeback for high performance. +> > +> > I would really appreciate if anyone could share +> your +> > experiences with ext3 from a production stand +> point or +> > any other suggestions for best read/write +> performance. +> > +> > Our applications is an hybrid of heavy +> inserts/updates +> > and DSS queries. +> > +> > version - postgres 7.3.2 +> > hardware - raid 5 (5 x 73 g hardware raid), 4g +> ram, 2 +> > * 2.8 GHz cpu, redhat 7.3 +> > +> > Note : we don't have the luxury of raid 1+0 +> (dedicated +> > disks) for xlog and clog files to start with but +> may +> > be down the line we might look into those options, +> but +> > for now i've planned on having them on local +> drives +> > rather than raid 5. +> > +> > thanks for any inputs, +> > Shankar +> > +> > +> > +> > +> > +> > +> > __________________________________________________ +> > Do you Yahoo!? +> > Yahoo! Platinum - Watch CBS' NCAA March Madness, +> live on your desktop! +> > http://platinum.yahoo.com +> > +> > +> > ---------------------------(end of +> broadcast)--------------------------- +> > TIP 1: subscribe and unsubscribe commands go to +> majordomo@postgresql.org +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster + + +__________________________________________________ +Do you Yahoo!? +Yahoo! Tax Center - File online, calculators, forms, and more +http://platinum.yahoo.com + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 12:53:56 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 19FDD475EEE + for ; + Tue, 1 Apr 2003 12:53:55 -0500 (EST) +Received: from l2.socialecology.com (unknown [4.42.179.131]) + by postgresql.org (Postfix) with ESMTP id ECDFF475E4D + for ; + Tue, 1 Apr 2003 12:53:49 -0500 (EST) +Received: from 4.42.179.151 (broccoli.socialecology.com [4.42.179.151]) + by l2.socialecology.com (Postfix) with SMTP + id 1481653B8B3; Tue, 1 Apr 2003 09:53:51 -0800 (PST) +X-Mailer: UserLand Frontier 9.1b2 (Macintosh OS) (mailServer v1.1..144) +Mime-Version: 1.0 +Message-Id: <26287373.1162931668@[4.42.179.151]> +X-authenticated-sender: erics +In-reply-to: <20030401173917.19476.qmail@web21101.mail.yahoo.com> +Date: Tue, 01 Apr 2003 09:53:48 -0800 +To: Shankar K , pgsql-performance@postgresql.org +Cc: Jeffrey D.Brower +From: eric soroos +Subject: Re: ext3 filesystem / linux 7.3 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-5.7 required=5.0 + tests=BAYES_20,IN_REP_TO,MAILTO_TO_SPAM_ADDR + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/4 +X-Sequence-Number: 1510 + +On Tue, 1 Apr 2003 09:39:17 -0800 (PST) in message <20030401173917.19476.qmail@web21101.mail.yahoo.com>, Shankar K wrote: +> hi jeff, +> +> go to +> http://www.ca.postgresql.org/docs/momjian/hw_performance/ +> under 'filesystems' slide. +> + +I suspect that is what he's seen. + + From my experience, ext3 is only a percent or two slower than ext2 under pg_bench. It saves an amazing amount of time on startup after a failure by not having to fsck to confirm that the filesystem is in a consistent state. + +I believe that ext3 is a metadata journaling system, and not a data journaling system. This would indicate that the PG transactioning is complimentary to the filesystem journaling, not duplication. + +eric + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 12:54:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 32E11475E4D + for ; + Tue, 1 Apr 2003 12:54:48 -0500 (EST) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP id 84FFA47592C + for ; + Tue, 1 Apr 2003 12:54:46 -0500 (EST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id h31HsjM25421; + Tue, 1 Apr 2003 12:54:45 -0500 (EST) +From: Bruce Momjian +Message-Id: <200304011754.h31HsjM25421@candle.pha.pa.us> +Subject: Re: ext3 filesystem / linux 7.3 +In-Reply-To: <20030401173917.19476.qmail@web21101.mail.yahoo.com> +To: Shankar K +Date: Tue, 1 Apr 2003 12:54:45 -0500 (EST) +Cc: pgsql-performance@postgresql.org, "Jeffrey D. Brower" +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Spam-Status: No, hits=-25.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,MAILTO_TO_SPAM_ADDR, + QUOTED_EMAIL_TEXT,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/5 +X-Sequence-Number: 1511 + + +I have heard XFS with the mount option is fastest. + +--------------------------------------------------------------------------- + +Shankar K wrote: +> hi jeff, +> +> go to +> http://www.ca.postgresql.org/docs/momjian/hw_performance/ +> under 'filesystems' slide. +> +> snip +> +> File system choice is particularly difficult on Linux +> because there are so many file system choices, and +> none of them are optimal: ext2 is not entirely +> crash-safe, ext3, XFS, and JFS are journal-based, and +> Reiser is optimized for small files and does +> journalling. The journalling file systems can be +> significantly slower than ext2 but when crash recovery +> is required, ext2 isn't an option. If ext2 must be +> used, mount it with sync enabled. Some people +> recommend XFS or an ext3 filesystem mounted with +> data=writeback. +> +> /snip +> +> --- "Jeffrey D. Brower" wrote: +> > What is the URL of that article? I understood that +> > ext2 was faster with PG +> > and so I went to a lot of trouble of creating an +> > ext2 partition just for PG +> > and gave up the journalling to do that. Something +> > about double effort since +> > PG already does a lot of that. +> > +> > Bruce, is there a final determination of which is +> > faster/safer? +> > +> > Jeff +> > +> > ----- Original Message ----- +> > From: "Shankar K" +> > To: +> > Sent: Monday, March 31, 2003 3:55 PM +> > Subject: [PERFORM] ext3 filesystem / linux 7.3 +> > +> > +> > > hi there, +> > > +> > > I was reading bruce's 'postgresql hardware +> > performance +> > > tuning' article and he has suggested ext3 +> > filesystem +> > > with data mode = writeback for high performance. +> > > +> > > I would really appreciate if anyone could share +> > your +> > > experiences with ext3 from a production stand +> > point or +> > > any other suggestions for best read/write +> > performance. +> > > +> > > Our applications is an hybrid of heavy +> > inserts/updates +> > > and DSS queries. +> > > +> > > version - postgres 7.3.2 +> > > hardware - raid 5 (5 x 73 g hardware raid), 4g +> > ram, 2 +> > > * 2.8 GHz cpu, redhat 7.3 +> > > +> > > Note : we don't have the luxury of raid 1+0 +> > (dedicated +> > > disks) for xlog and clog files to start with but +> > may +> > > be down the line we might look into those options, +> > but +> > > for now i've planned on having them on local +> > drives +> > > rather than raid 5. +> > > +> > > thanks for any inputs, +> > > Shankar +> > > +> > > +> > > +> > > +> > > +> > > +> > > __________________________________________________ +> > > Do you Yahoo!? +> > > Yahoo! Platinum - Watch CBS' NCAA March Madness, +> > live on your desktop! +> > > http://platinum.yahoo.com +> > > +> > > +> > > ---------------------------(end of +> > broadcast)--------------------------- +> > > TIP 1: subscribe and unsubscribe commands go to +> > majordomo@postgresql.org +> > +> > +> > ---------------------------(end of +> > broadcast)--------------------------- +> > TIP 4: Don't 'kill -9' the postmaster +> +> +> __________________________________________________ +> Do you Yahoo!? +> Yahoo! Tax Center - File online, calculators, forms, and more +> http://platinum.yahoo.com +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the unregister command +> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) +> + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 12:55:15 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C8A2A475F34 + for ; + Tue, 1 Apr 2003 12:55:13 -0500 (EST) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 3F21D475E4D + for ; + Tue, 1 Apr 2003 12:55:13 -0500 (EST) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 190Pyh-00017A-00 + for ; Tue, 01 Apr 2003 12:55:19 -0500 +Received: from andrew by dba2 with local (Exim 3.36 #1 (Debian)) + id 190Pyh-0002Xm-00 + for ; Tue, 01 Apr 2003 12:55:19 -0500 +Date: Tue, 1 Apr 2003 12:55:19 -0500 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Message-ID: <20030401175519.GA9553@mail> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> + <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-34.8 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/6 +X-Sequence-Number: 1512 + +On Tue, Apr 01, 2003 at 12:33:15PM -0500, Jeffrey D. Brower wrote: +> What is the URL of that article? I understood that ext2 was faster with PG +> and so I went to a lot of trouble of creating an ext2 partition just for PG +> and gave up the journalling to do that. Something about double effort since +> PG already does a lot of that. + +I don't know how ext3 could be faster than ext2, since it has to do +more work. + +But ext2 is not crash-safe. So your data could well be hosed if you +come back from a crash on ext2. + +Actually, I have my doubts about _any_ of the journaling filesystems +for Linux: ext3 has a reputation for being slow if you journal in the +real-safe mode, and there have been so many unrepeatable reiserfs +problem reports that I'm loathe to use it for real systems. I had +exceptionally good experiences with xfs when I was admining SGI +boxes, but that's not part of the standard Linux kernel distribution, +and with no idea why, I think my managers would get grumpy with me +for using it. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 13:26:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8749E475CBC + for ; + Tue, 1 Apr 2003 13:26:13 -0500 (EST) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP id 34DF4475AF8 + for ; + Tue, 1 Apr 2003 13:26:12 -0500 (EST) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id h31IQ2S29201; + Tue, 1 Apr 2003 13:26:02 -0500 (EST) +From: Bruce Momjian +Message-Id: <200304011826.h31IQ2S29201@candle.pha.pa.us> +Subject: Re: ext3 filesystem / linux 7.3 +In-Reply-To: <26287373.1162931668@[4.42.179.151]> +To: eric soroos +Date: Tue, 1 Apr 2003 13:26:02 -0500 (EST) +Cc: Shankar K , pgsql-performance@postgresql.org, + "Jeffrey D.Brower" +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Spam-Status: No, hits=-25.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,MAILTO_TO_SPAM_ADDR, + QUOTED_EMAIL_TEXT,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/7 +X-Sequence-Number: 1513 + +eric soroos wrote: +> On Tue, 1 Apr 2003 09:39:17 -0800 (PST) in message +> <20030401173917.19476.qmail@web21101.mail.yahoo.com>, Shankar +> K wrote: +> > hi jeff, +> > +> > go to +> > http://www.ca.postgresql.org/docs/momjian/hw_performance/ +> > under 'filesystems' slide. +> > +> +> I suspect that is what he's seen. +> +> >From my experience, ext3 is only a percent or two slower than ext2 under pg_bench. It saves an amazing amount of time on startup after a failure by not having to fsck to confirm that the filesystem is in a consistent state. +> +> I believe that ext3 is a metadata journaling system, and not a +> data journaling system. This would indicate that the PG +> transactioning is complimentary to the filesystem journaling, +> not duplication. + +Ext3 is only metadata journaling if you set the mount flags as +described. I also don't think pgbench is the best test for testing file +system performance. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 14:27:38 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EC04747621C + for ; + Tue, 1 Apr 2003 14:27:35 -0500 (EST) +Received: from mailrelay (technicacorp.com [216.181.29.134]) + by postgresql.org (Postfix) with ESMTP id D4A364760CC + for ; + Tue, 1 Apr 2003 14:27:34 -0500 (EST) +thread-index: AcL4hLkaPHjk8tWvTL+s4AJ78XT9fw== +Content-Transfer-Encoding: 7bit +Received: from WWWSERVER.technicacorp.com ([216.181.29.149]) by mailrelay with + Microsoft SMTPSVC(5.0.2195.5329); Tue, 1 Apr 2003 14:27:21 -0500 +Content-Class: urn:content-classes:message +Importance: normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Received: by wwwserver with Internet Mail Service (5.5.2656.59) id ; + Tue, 1 Apr 2003 14:31:13 -0500 +Message-ID: <71F044551C53974EB0735B3737EFE2FC088645@wwwserver> +From: "Scott Buchan" +To: +Subject: Postgresql performance on Solaris +Date: Tue, 1 Apr 2003 14:31:13 -0500 +MIME-Version: 1.0 +X-Mailer: Internet Mail Service (5.5.2656.59) +Content-Type: multipart/alternative; + boundary="----_=_NextPart_001_01C2F885.4198FFC0" +X-OriginalArrivalTime: 01 Apr 2003 19:27:21.0186 (UTC) + FILETIME=[B7259420:01C2F884] +X-Spam-Status: No, hits=-5.7 required=5.0 + tests=BAYES_10,HTML_50_60,MISSING_OUTLOOK_NAME version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/8 +X-Sequence-Number: 1514 + +This is a multi-part message in MIME format. + +------_=_NextPart_001_01C2F885.4198FFC0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; + charset="iso-8859-1" + +Hi, + + + +I am getting poor performance from my postgresql (version 7.3.2 compiled +with gcc 2.95.2) database when running load tests on my web application. +The database works great until I get above 200 concurrent users. The +following query runtime will vary from: + + + +explain analyze select TIMESTAMP, SPM_CONVSRCADDR, + +SPM_CONVDSTADDR, SPM_CONVSRCPORT, SPM_CONVDSTPORT, + +SPM_CONVPROTO, ACTION from FirewallLogs where TimeStamp>=1044939600000 + +and TimeStamp<=1047391020000 and spm_subid='462' and fqdn ='bs2@pcp' order +by + +timestamp desc; + + QUERY +PLAN + +---------------------------------------------------------------------------- +----------------------------------------------------------------------- + + Sort (cost=3525.27..3527.49 rows=888 width=47) (actual time=55.65..56.16 +rows=913 loops=1) + + Sort Key: "timestamp" + + -> Index Scan using firewalllogsindex on firewalllogs +(cost=0.00..3481.77 rows=888 width=47) (actual time=0.40..50.33 rows=913 +loops=1) + + Index Cond: ((fqdn = 'bs2@pcp'::character varying) AND ("timestamp" +>= 1044939600000::bigint) AND ("timestamp" <= 1047391020000::bigint)) + + Filter: (spm_subid = 462) + + Total runtime: 57.36 msec + +(6 rows) + + + +to + + + + QUERY +PLAN + +---------------------------------------------------------------------------- +----------------------------------------------------------------------- + + Sort (cost=3525.27..3527.49 rows=888 width=47) (actual +time=2323.79..2324.31 rows=913 loops=1) + + Sort Key: "timestamp" + + -> Index Scan using firewalllogsindex on firewalllogs +(cost=0.00..3481.77 rows=888 width=47) (actual time=0.26..2318.11 rows=913 +loops=1) + + Index Cond: ((fqdn = 'bs2@pcp'::character varying) AND ("timestamp" +>= 1044939600000::bigint) AND ("timestamp" <= 1047391020000::bigint)) + + Filter: (spm_subid = 462) + + Total runtime: 2325.62 msec + +(6 rows) + + + +NOTE: I am only performing select queries - no inserts, deletes or updates. + + +I am running postgresql on a SunFire v880 with 4 750MHz sparcv9 processors +with 8 Gig of RAM running solaris 8. I have 2 tables with 500,000 records +in each and both tables are indexed. I am connecting to the database +through JDBC using a pool of connections (tried pools of 50, 100, and 200 +with similar results). When running the load tests, the cpu of the box is +always above 60% idle. I have run iostat and I am not seeing any problems +with io. + + + +I have tried different size shared_buffers from 4100 to 64000, and I have +added the following to the /etc/system file: + + + +set shmsys:shminfo_shmmax=0xffffffff + +set shmsys:shminfo_shmmin=1 + +set shmsys:shminfo_shmmni=256 + +set shmsys:shminfo_shmseg=256 + +set semsys:seminfo_semmap=256 + +set semsys:seminfo_semmni=512 + +set semsys:seminfo_semmns=512 + +set semsys:seminfo_semmsl=32 + + + +I understand that this could be a problem with the kernel and not postgresql +but I am at a loss at what to change to get better performance out of the +database or the kernel. + + + +Any help would be appreciated. + + + + + + +------_=_NextPart_001_01C2F885.4198FFC0 +Content-Type: text/html; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable + + + + + + + + + + + + + + + +
+ +

Hi,

+ +

 

+ +

I am getting poor performance from my postgresql (version +7.3.2 compiled with gcc 2.95.2) database when running load tests on my web +application.  The database works great until I get above 200 concurrent +users.  The following query runtime will vary from:

+ +

 

+ +

explain analyze select TIMESTAMP, SPM_CONVSRCADDR,

+ +

SPM_CONVDSTADDR, SPM_CONVSRCPORT, SPM_CONVDSTPORT,

+ +

SPM_CONVPROTO, ACTION from FirewallLogs where TimeStamp&= +gt;=3D1044939600000

+ +

and TimeStamp<=3D1047391020000 and spm_subid=3D'462' = +and fqdn +=3D'bs2@pcp' order by

+ +

timestamp desc;

+ +

         &n= +bsp;            = +;            &n= +bsp;            = +;            &n= +bsp;        +QUERY +PLAN            = +;            &n= +bsp;      +

+ +

--------------------------------------------------------= +---------------------------------------------------------------------------= +----------------

+ +

 Sort  (cost=3D3525.27..3527.49 rows=3D888 wid= +th=3D47) +(actual time=3D55.65..56.16 rows=3D913 loops=3D1)

+ +

   Sort Key: "timestamp"

+ +

   ->  Index Scan using firewalllogsin= +dex +on firewalllogs  (cost=3D0.00..3481.77 rows=3D888 width=3D47) (actual +time=3D0.40..50.33 rows=3D913 loops=3D1)

+ +

         Index C= +ond: +((fqdn =3D 'bs2@pcp'::character varying) AND ("timestamp" >=3D +1044939600000::bigint) AND ("timestamp" <=3D 1047391020000::bi= +gint))

+ +

         Filter:= + (spm_subid +=3D 462)

+ +

 Total runtime: 57.36 msec

+ +

(6 rows)

+ +

 

+ +

to

+ +

 

+ +

         &n= +bsp;            = +;            &n= +bsp;            = +;            &n= +bsp;        +QUERY +PLAN            = +;            &n= +bsp;      +

+ +

--------------------------------------------------------= +---------------------------------------------------------------------------= +----------------

+ +

 Sort  (cost=3D3525.27..3527.49 rows=3D888 wid= +th=3D47) +(actual time=3D2323.79..2324.31 rows=3D913 loops=3D1)

+ +

   Sort Key: "timestamp"

+ +

   ->  Index Scan using firewalllogsin= +dex +on firewalllogs  (cost=3D0.00..3481.77 rows=3D888 width=3D47) (actual +time=3D0.26..2318.11 rows=3D913 loops=3D1)

+ +

         Index C= +ond: +((fqdn =3D 'bs2@pcp'::character varying) AND ("timestamp" >=3D +1044939600000::bigint) AND ("timestamp" <=3D 1047391020000::bi= +gint))

+ +

         Filter:= + (spm_subid +=3D 462)

+ +

 Total runtime: 2325.62 msec

+ +

(6 rows)

+ +

 

+ +

NOTE:  I am only performing select queries - no ins= +erts, +deletes or updates. 

+ +

I am running postgresql on a SunFire v880 = +with +4 750MHz sparcv9 processors with 8 Gig of RAM running solaris 8.  I ha= +ve 2 +tables with 500,000 records in each and both tables are indexed.  I am +connecting to the database through JDBC using a pool of connections (tried +pools of 50, 100, and 200 with similar results).  When running the load +tests, the cpu of the box is always above 60% idle.  I have run iostat= + and +I am not seeing any problems with io.

+ +

 

+ +

I have tried different size shared_buffers from 4100 to 64000, and I +have added the following to the /etc/system file:

+ +

 

+ +

set shmsys:shminfo_shmmax=3D0xffffffff

+ +

set shmsys:shminfo_shmmin=3D1

+ +

set shmsys:shminfo_shmmni=3D256

+ +

set shmsys:shminfo_shmseg=3D256

+ +

set semsys:seminfo_semmap=3D256

+ +

set semsys:seminfo_semmni=3D512

+ +

set semsys:seminfo_semmns=3D512

+ +

set semsys:seminfo_semmsl=3D32

+ +

 

+ +

I understand that this could be a problem with the kernel +and not postgresql but I am at a loss at what to change to get better +performance out of the database or the kernel.

+ +

 

+ +

Any help would be appreciated.

+ +

 

+ +

 

+ +
+ + + + + +------_=_NextPart_001_01C2F885.4198FFC0-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 15:21:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3167A47621C + for ; + Tue, 1 Apr 2003 15:21:43 -0500 (EST) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 67417476178 + for ; + Tue, 1 Apr 2003 15:21:42 -0500 (EST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h31KLh2L002852; + Tue, 1 Apr 2003 15:21:43 -0500 (EST) +To: "Scott Buchan" +Cc: pgsql-performance@postgresql.org +Subject: Re: Postgresql performance on Solaris +In-reply-to: <71F044551C53974EB0735B3737EFE2FC088645@wwwserver> +References: <71F044551C53974EB0735B3737EFE2FC088645@wwwserver> +Comments: In-reply-to "Scott Buchan" + message dated "Tue, 01 Apr 2003 14:31:13 -0500" +Date: Tue, 01 Apr 2003 15:21:43 -0500 +Message-ID: <2851.1049228503@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/9 +X-Sequence-Number: 1515 + +"Scott Buchan" writes: +> I am getting poor performance from my postgresql (version 7.3.2 compiled +> with gcc 2.95.2) database when running load tests on my web application. +> The database works great until I get above 200 concurrent users. + +Hmm ... that sounds kinda familiar; you might check the archives for +similar reports from Solaris users. AFAIR we didn't figure out the +problem yet, but there's some raw data available. + +> When running the load tests, the cpu of the box is always above 60% +> idle. I have run iostat and I am not seeing any problems with io. + +[ scratches head ... ] If the bottleneck isn't CPU, and it isn't I/O, +then what could it be? You sure about the above observations? (Does +iostat include swap activity on that platform?) + +The only other idea I can think of is that there's some weird effect in +the locking code (which only shows up with lots of concurrent backends) +such that would-be lockers repeatedly fail and sleep when they should +have gotten the lock. If you can figure out how to tell the difference +between a backend waiting for disk I/O and one waiting for a semaphore +or sleeping, it'd be interesting to see what the majority of the +backends are doing. + +Another way to try to gather some data is to attach to one of the +backend processes with a debugger, and just stop it to get a stack trace +every so often. If the stack traces tend to point to the same place +that would give some info about the bottleneck. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 15:36:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E5951475CBC + for ; + Tue, 1 Apr 2003 15:36:47 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id E6E2D475AF8 + for ; + Tue, 1 Apr 2003 15:36:46 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h31KPDr11175; + Tue, 1 Apr 2003 15:25:13 -0500 +Message-ID: <093201c2f88f$45e60730$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Bruce Momjian" , + "eric soroos" +Cc: "Shankar K" , + +References: <200304011826.h31IQ2S29201@candle.pha.pa.us> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Tue, 1 Apr 2003 15:42:54 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-6.5 required=5.0 + tests=BAYES_30,RCVD_IN_NJABL,REFERENCES,X_NJABL_OPEN_PROXY + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/10 +X-Sequence-Number: 1516 + +OK so am I hearing: + +XFS is the fastest (but is it the safest?) but does not come on Linux. + +Ext2 does less work than Ext3 so is fastest among what DOES come with +Linux - but if you have a crash that fsck can't fix you're hosed. + +Ext3 is quite a bit slower if set to be real safe, a wee bit slower if run +with standard options which makes it more crash-safe, and much slower if the +mount flags are set to metadata journaling but that is much safer as a file +system because the metadata journaling is complementary to the PG +transactioning. + +To determine which you want you must choose which one feels to you like the +right balance of speed and the setup work you are willing to perform and +maintain. + +Do I have it right? + + Jeff + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 15:43:37 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AC51C475AF8 + for ; + Tue, 1 Apr 2003 15:43:36 -0500 (EST) +Received: from hal.istation.com (hal.istation.com [65.120.151.132]) + by postgresql.org (Postfix) with ESMTP id D1E7247592C + for ; + Tue, 1 Apr 2003 15:43:35 -0500 (EST) +Received: from sauron (sauron.istation.com [65.120.151.174]) (authenticated) + by hal.istation.com (8.11.6/8.11.6) with ESMTP id h31KhXK03610; + Tue, 1 Apr 2003 14:43:33 -0600 +Reply-To: +From: "Keith Bottner" +To: "'Andrew Sullivan'" , + +Subject: Re: ext3 filesystem / linux 7.3 +Date: Tue, 1 Apr 2003 14:43:35 -0600 +Organization: istation.com +Message-ID: <000a01c2f88f$5e288200$ae977841@istation.com> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.3416 +In-reply-to: <20030401175519.GA9553@mail> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-37.3 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,ORIGINAL_MESSAGE, + QUOTED_EMAIL_TEXT,REPLY_WITH_QUOTES,SIGNATURE_LONG_SPARSE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/11 +X-Sequence-Number: 1517 + +FYI, I believe that XFS will be included in the 2.6 kernel. + +Keith Bottner +kbottner@istation.com + +-----Original Message----- +From: pgsql-performance-owner@postgresql.org +[mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Andrew +Sullivan +Sent: Tuesday, April 01, 2003 11:55 AM +To: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] ext3 filesystem / linux 7.3 + + +On Tue, Apr 01, 2003 at 12:33:15PM -0500, Jeffrey D. Brower wrote: +> What is the URL of that article? I understood that ext2 was faster +> with PG and so I went to a lot of trouble of creating an ext2 +> partition just for PG and gave up the journalling to do that. +> Something about double effort since PG already does a lot of that. + +I don't know how ext3 could be faster than ext2, since it has to do more +work. + +But ext2 is not crash-safe. So your data could well be hosed if you +come back from a crash on ext2. + +Actually, I have my doubts about _any_ of the journaling filesystems for +Linux: ext3 has a reputation for being slow if you journal in the +real-safe mode, and there have been so many unrepeatable reiserfs +problem reports that I'm loathe to use it for real systems. I had +exceptionally good experiences with xfs when I was admining SGI boxes, +but that's not part of the standard Linux kernel distribution, and with +no idea why, I think my managers would get grumpy with me for using it. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +---------------------------(end of broadcast)--------------------------- +TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 16:48:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9549A475EC9 + for ; + Tue, 1 Apr 2003 16:48:01 -0500 (EST) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id A51E9475CBC + for ; + Tue, 1 Apr 2003 16:47:31 -0500 (EST) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h31LjHYS006757; + Tue, 1 Apr 2003 14:45:17 -0700 (MST) +Date: Tue, 1 Apr 2003 14:42:59 -0700 (MST) +From: "scott.marlowe" +To: Tom Lane +Cc: Scott Buchan , + +Subject: Re: Postgresql performance on Solaris +In-Reply-To: <2851.1049228503@sss.pgh.pa.us> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/12 +X-Sequence-Number: 1518 + +On Tue, 1 Apr 2003, Tom Lane wrote: + +> The only other idea I can think of is that there's some weird effect in +> the locking code (which only shows up with lots of concurrent backends) +> such that would-be lockers repeatedly fail and sleep when they should +> have gotten the lock. If you can figure out how to tell the difference +> between a backend waiting for disk I/O and one waiting for a semaphore +> or sleeping, it'd be interesting to see what the majority of the +> backends are doing. + +I was thinking along the lines of it being something like the old Linux +kernel had with apache and other programs with waking all the processes. +It could be that something about Solaris is meaning that every backend +process, no matter how idle they are, get "touched" every time something +is done. Just guessing. + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 20:34:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4713A475AF8 + for ; + Tue, 1 Apr 2003 20:34:16 -0500 (EST) +Received: from houston.familyhealth.com.au (unknown [203.59.48.253]) + by postgresql.org (Postfix) with ESMTP id 1CA4F47592C + for ; + Tue, 1 Apr 2003 20:34:12 -0500 (EST) +Received: (from root@localhost) + by houston.familyhealth.com.au (8.11.6p2/8.11.6) id h321YC112120 + for pgsql-performance@postgresql.org; + Wed, 2 Apr 2003 09:34:12 +0800 (WST) + (envelope-from chriskl@familyhealth.com.au) +Received: from mariner (mariner.internal [192.168.0.101]) + by houston.familyhealth.com.au (8.11.6p2/8.9.3) with SMTP id + h321Xp711809; Wed, 2 Apr 2003 09:33:53 +0800 (WST) +Message-ID: <061501c2f8b7$f5280720$6500a8c0@fhp.internal> +From: "Christopher Kings-Lynne" +To: "Jeffrey D. Brower" , + "Bruce Momjian" , + "eric soroos" +Cc: "Shankar K" , + +References: <200304011826.h31IQ2S29201@candle.pha.pa.us> + <093201c2f88f$45e60730$0b02a8c0@pointhere.net> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 09:33:56 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: base64 +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-scanner: scanned by Inflex 0.1.5c - (http://www.inflex.co.za/) +X-Spam-Status: No, hits=-10.5 required=5.0 + tests=BASE64_ENC_TEXT,BAYES_20,MAILTO_TO_SPAM_ADDR, + QUOTED_EMAIL_TEXT,REFERENCES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/13 +X-Sequence-Number: 1519 + +SnVzdCBzd2l0Y2ggdG8gRnJlZUJTRCBhbmQgdXNlIFVGUyA7KQ0KDQpDaHJp +cw0KDQotLS0tLSBPcmlnaW5hbCBNZXNzYWdlIC0tLS0tIA0KRnJvbTogIkpl +ZmZyZXkgRC4gQnJvd2VyIiA8amVmZkBwb2ludGhlcmUubmV0Pg0KVG86ICJC +cnVjZSBNb21qaWFuIiA8cGdtYW5AY2FuZGxlLnBoYS5wYS51cz47ICJlcmlj +IHNvcm9vcyIgPGVyaWMtcHNxbEBzb3Jvb3MubmV0Pg0KQ2M6ICJTaGFua2Fy +IEsiIDxzaGFuMDA3NUB5YWhvby5jb20+OyA8cGdzcWwtcGVyZm9ybWFuY2VA +cG9zdGdyZXNxbC5vcmc+DQpTZW50OiBXZWRuZXNkYXksIEFwcmlsIDAyLCAy +MDAzIDQ6NDIgQU0NClN1YmplY3Q6IFJlOiBbUEVSRk9STV0gZXh0MyBmaWxl +c3lzdGVtIC8gbGludXggNy4zDQoNCg0KPiBPSyBzbyBhbSBJIGhlYXJpbmc6 +DQo+IA0KPiBYRlMgaXMgdGhlIGZhc3Rlc3QgKGJ1dCBpcyBpdCB0aGUgc2Fm +ZXN0PykgYnV0IGRvZXMgbm90IGNvbWUgb24gTGludXguDQo+IA0KPiBFeHQy +IGRvZXMgbGVzcyB3b3JrIHRoYW4gRXh0MyBzbyBpcyBmYXN0ZXN0IGFtb25n +IHdoYXQgRE9FUyBjb21lIHdpdGgNCj4gTGludXggLSBidXQgaWYgeW91IGhh +dmUgYSBjcmFzaCB0aGF0IGZzY2sgY2FuJ3QgZml4IHlvdSdyZSBob3NlZC4N +Cj4gDQo+IEV4dDMgaXMgcXVpdGUgYSBiaXQgc2xvd2VyIGlmIHNldCB0byBi +ZSByZWFsIHNhZmUsIGEgd2VlIGJpdCBzbG93ZXIgaWYgcnVuDQo+IHdpdGgg +c3RhbmRhcmQgb3B0aW9ucyB3aGljaCBtYWtlcyBpdCBtb3JlIGNyYXNoLXNh +ZmUsIGFuZCBtdWNoIHNsb3dlciBpZiB0aGUNCj4gbW91bnQgZmxhZ3MgYXJl +IHNldCB0byBtZXRhZGF0YSBqb3VybmFsaW5nIGJ1dCB0aGF0IGlzIG11Y2gg +c2FmZXIgYXMgYSBmaWxlDQo+IHN5c3RlbSBiZWNhdXNlIHRoZSBtZXRhZGF0 +YSBqb3VybmFsaW5nIGlzIGNvbXBsZW1lbnRhcnkgdG8gdGhlIFBHDQo+IHRy +YW5zYWN0aW9uaW5nLg0KPiANCj4gVG8gZGV0ZXJtaW5lIHdoaWNoIHlvdSB3 +YW50IHlvdSBtdXN0IGNob29zZSB3aGljaCBvbmUgZmVlbHMgdG8geW91IGxp +a2UgdGhlDQo+IHJpZ2h0IGJhbGFuY2Ugb2Ygc3BlZWQgYW5kIHRoZSBzZXR1 +cCB3b3JrIHlvdSBhcmUgd2lsbGluZyB0byBwZXJmb3JtIGFuZA0KPiBtYWlu +dGFpbi4NCj4gDQo+IERvIEkgaGF2ZSBpdCByaWdodD8NCj4gDQo+ICAgIEpl +ZmYNCj4gDQo+IA0KPiAtLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0oZW5k +IG9mIGJyb2FkY2FzdCktLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0tLS0NCj4g +VElQIDM6IGlmIHBvc3RpbmcvcmVhZGluZyB0aHJvdWdoIFVzZW5ldCwgcGxl +YXNlIHNlbmQgYW4gYXBwcm9wcmlhdGUNCj4gc3Vic2NyaWJlLW5vbWFpbCBj +b21tYW5kIHRvIG1ham9yZG9tb0Bwb3N0Z3Jlc3FsLm9yZyBzbyB0aGF0IHlv +dXINCj4gbWVzc2FnZSBjYW4gZ2V0IHRocm91Z2ggdG8gdGhlIG1haWxpbmcg +bGlzdCBjbGVhbmx5DQo+IA== + +From pgsql-performance-owner@postgresql.org Tue Apr 1 20:49:40 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 87BE947592C + for ; + Tue, 1 Apr 2003 20:49:38 -0500 (EST) +Received: from perrin.int.nxad.com (internal.ext.nxad.com [69.1.70.251]) + by postgresql.org (Postfix) with ESMTP id A89D84758C9 + for ; + Tue, 1 Apr 2003 20:49:07 -0500 (EST) +Received: by perrin.int.nxad.com (Postfix, from userid 1001) + id DC4B22106C; Tue, 1 Apr 2003 17:49:06 -0800 (PST) +Date: Tue, 1 Apr 2003 17:49:06 -0800 +From: Sean Chittenden +To: Christopher Kings-Lynne +Cc: "Jeffrey D. Brower" , + Bruce Momjian , + eric soroos , Shankar K , + pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Message-ID: <20030402014906.GL10799@perrin.int.nxad.com> +References: <200304011826.h31IQ2S29201@candle.pha.pa.us> + <093201c2f88f$45e60730$0b02a8c0@pointhere.net> + <061501c2f8b7$f5280720$6500a8c0@fhp.internal> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <061501c2f8b7$f5280720$6500a8c0@fhp.internal> +User-Agent: Mutt/1.4i +X-PGP-Key: finger seanc@FreeBSD.org +X-PGP-Fingerprint: 3849 3760 1AFE 7B17 11A0 83A6 DD99 E31F BC84 B341 +X-Web-Homepage: http://sean.chittenden.org/ +X-Spam-Status: No, hits=-21.8 required=5.0 + tests=BAYES_10,IN_REP_TO,REFERENCES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/14 +X-Sequence-Number: 1520 + +> Just switch to FreeBSD and use UFS ;) + +I must say, I found this whole discussion rather amusing on the +sidelines given it's largely a non-problem for non-Linux users. :) + +"Better performance through engineering elegance." + +-sc + +-- +Sean Chittenden +seanc@FreeBSD.org + + +From pgsql-performance-owner@postgresql.org Tue Apr 1 23:11:37 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9680C475AF8 + for ; + Tue, 1 Apr 2003 23:11:35 -0500 (EST) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 6DF134758C9 + for ; + Tue, 1 Apr 2003 23:11:33 -0500 (EST) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h324Bam30839 + for ; Wed, 2 Apr 2003 09:41:36 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h324BZ730829 + for ; Wed, 2 Apr 2003 09:41:36 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 09:42:18 +0530 +User-Agent: KMail/1.5 +References: <200304011826.h31IQ2S29201@candle.pha.pa.us> + <061501c2f8b7$f5280720$6500a8c0@fhp.internal> + <20030402014906.GL10799@perrin.int.nxad.com> +In-Reply-To: <20030402014906.GL10799@perrin.int.nxad.com> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304020942.18320.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/15 +X-Sequence-Number: 1521 + +On Wednesday 02 April 2003 07:19, you wrote: +> > Just switch to FreeBSD and use UFS ;) +> +> I must say, I found this whole discussion rather amusing on the +> sidelines given it's largely a non-problem for non-Linux users. :) +> +> "Better performance through engineering elegance." + +Well, this may sound like a troll, but I have said this before and will say +that again. I found reiserfs to be faster than ext2, upto 40% at times when +we tried a quasi closed source benchmark on a quad xeon machine with SCSI +RAID. + +Everything else being same and defaults used out of box, reiserfs on mandrake9 +was far faster in every respect than ext2. + +I personally find freeBSD UFS to be a better combo based on my workstation +tests. I believe freeBSD has a better IO scheuler that utilises disk +bandwidth in optimal manner. Scratching (my poor IDE) disk like mad does not +happen with freeBSD but linux does it plenty. But I didn't benchmark it for +throughput.. + + Shridhar + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 10:13:50 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8EF55475EC9 + for ; + Wed, 2 Apr 2003 10:13:48 -0500 (EST) +Received: from smtp.inode.at (smtp-05.inode.at [62.99.194.7]) + by postgresql.org (Postfix) with ESMTP id 2B4A94762A2 + for ; + Wed, 2 Apr 2003 10:13:17 -0500 (EST) +Received: from line-f-208.adsl-dynamic.inode.at ([62.99.193.208]:50006 + helo=andi-lap) by smtp.inode.at with smtp (Exim 4.10) + id 190juh-0002HL-00; Wed, 02 Apr 2003 17:12:31 +0200 +Received: by andi-lap (sSMTP sendmail emulation); + Wed, 2 Apr 2003 17:13:19 +0200 +Subject: Re: ext3 filesystem / linux 7.3 +From: Andreas Kostyrka +To: eric soroos +Cc: Shankar K , pgsql-performance@postgresql.org, + "Jeffrey D.Brower" +In-Reply-To: <26287373.1162931668@[4.42.179.151]> +References: <26287373.1162931668@[4.42.179.151]> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-iHBxP95beFH/1eZFAO/T" +Organization: +Message-Id: <1049296398.20242.325.camel@andi-lap> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 +Date: 02 Apr 2003 17:13:19 +0200 +X-Spam-Status: No, hits=-41.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,MAILTO_TO_SPAM_ADDR, + PGP_SIGNATURE_2,REFERENCES,REPLY_WITH_QUOTES, USER_AGENT_XIMIAN + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/16 +X-Sequence-Number: 1522 + +--=-iHBxP95beFH/1eZFAO/T +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Tue, 2003-04-01 at 19:53, eric soroos wrote: +> On Tue, 1 Apr 2003 09:39:17 -0800 (PST) in message <20030401173917.19476.= +qmail@web21101.mail.yahoo.com>, Shankar K wrote: +> > hi jeff, +> >=20 +> > go to +> > http://www.ca.postgresql.org/docs/momjian/hw_performance/ +> > under 'filesystems' slide. +> >=20 +>=20 +> I suspect that is what he's seen.=20 +>=20 +> >From my experience, ext3 is only a percent or two slower than ext2 under= + pg_bench. It saves an amazing amount of time on startup after a failure by= + not having to fsck to confirm that the filesystem is in a consistent state= +.=20 +>=20 +> I believe that ext3 is a metadata journaling system, and not a data journ= +aling system. This would indicate that the PG transactioning is complimenta= +ry to the filesystem journaling, not duplication.=20 +It's both. See the -o data=3Djournal|data=3Dordered|data=3Dwriteback mount +time option. + +Andreas + +--=-iHBxP95beFH/1eZFAO/T +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (GNU/Linux) + +iD8DBQA+iv4LHJdudm4KnO0RArZyAKCO6sa/eRlkzAoNfF+NTzctQcWVCgCgnxL2 +S5jjDm1agDbaXwJ5yfvsCAA= +=hAhH +-----END PGP SIGNATURE----- + +--=-iHBxP95beFH/1eZFAO/T-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 10:18:57 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0873C475E91 + for ; + Wed, 2 Apr 2003 10:18:56 -0500 (EST) +Received: from smtp.inode.at (smtp-05.inode.at [62.99.194.7]) + by postgresql.org (Postfix) with ESMTP id F1E044761BC + for ; + Wed, 2 Apr 2003 10:18:23 -0500 (EST) +Received: from line-f-208.adsl-dynamic.inode.at ([62.99.193.208]:50007 + helo=andi-lap) by smtp.inode.at with smtp (Exim 4.10) + id 190jze-0002NJ-00; Wed, 02 Apr 2003 17:17:39 +0200 +Received: by andi-lap (sSMTP sendmail emulation); + Wed, 2 Apr 2003 17:18:26 +0200 +Subject: Re: ext3 filesystem / linux 7.3 +From: Andreas Kostyrka +To: Andrew Sullivan +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20030401175519.GA9553@mail> +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> + <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> + <20030401175519.GA9553@mail> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-5PeF+BN/Yk0fBfEJzJPZ" +Organization: +Message-Id: <1049296706.20242.331.camel@andi-lap> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 +Date: 02 Apr 2003 17:18:26 +0200 +X-Spam-Status: No, hits=-44.9 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,QUOTE_TWICE_1,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/17 +X-Sequence-Number: 1523 + +--=-5PeF+BN/Yk0fBfEJzJPZ +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Tue, 2003-04-01 at 19:55, Andrew Sullivan wrote: +> I don't know how ext3 could be faster than ext2, since it has to do +> more work.=20=20 +Depending upon certain parameters, it can be faster, because it writes +the data to the journal serially without head movement. The kernel might +be able to write that data in it spot later when the hdd would be idle. + +So yes, in certain cases, ext3 might be faster than ext2. + +>=20 +> Actually, I have my doubts about _any_ of the journaling filesystems +> for Linux: ext3 has a reputation for being slow if you journal in the +Well, journaled filesystem usually means only meta-data journaling. ext3 +is the only LinuxFS (AFAIK) that offers a fully journaled fs. +> real-safe mode, and there have been so many unrepeatable reiserfs +> problem reports that I'm loathe to use it for real systems. I had +Well, I've been using ReiserFS now for years, and never had any problems +with it.=20 + +Andreas +--=20 +Andreas Kostyrka +Josef-Mayer-Strasse 5 +83043 Bad Aibling + +--=-5PeF+BN/Yk0fBfEJzJPZ +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (GNU/Linux) + +iD8DBQA+iv9CHJdudm4KnO0RAu8cAJ4+8s8WWe0/UeD6jGsTj5QFr76xTQCgs/M7 +qgi3zPi80UTp8aLCDKdNxd4= +=Pi/W +-----END PGP SIGNATURE----- + +--=-5PeF+BN/Yk0fBfEJzJPZ-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 10:31:47 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0A354475CBC + for ; + Wed, 2 Apr 2003 10:31:46 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id 95B2C475EC9 + for ; + Wed, 2 Apr 2003 10:31:13 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h32FJs905259; + Wed, 2 Apr 2003 10:19:54 -0500 +Message-ID: <0a3001c2f92d$c975a490$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Andreas Kostyrka" , + "eric soroos" +Cc: "Shankar K" , + +References: <26287373.1162931668@[4.42.179.151]> + <1049296398.20242.325.camel@andi-lap> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 10:37:36 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-6.5 required=5.0 + tests=BAYES_30,RCVD_IN_NJABL,REFERENCES,X_NJABL_OPEN_PROXY + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/18 +X-Sequence-Number: 1524 + +... and what *exactly* is the difference? + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 10:48:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C4DE2474E44 + for ; + Wed, 2 Apr 2003 10:48:04 -0500 (EST) +Received: from smtp.inode.at (smtp-05.inode.at [62.99.194.7]) + by postgresql.org (Postfix) with ESMTP id C41A6474E44 + for ; + Wed, 2 Apr 2003 10:47:32 -0500 (EST) +Received: from line-f-208.adsl-dynamic.inode.at ([62.99.193.208]:50055 + helo=andi-lap) by smtp.inode.at with smtp (Exim 4.10) + id 190kRr-0002pX-00; Wed, 02 Apr 2003 17:46:48 +0200 +Received: by andi-lap (sSMTP sendmail emulation); + Wed, 2 Apr 2003 17:47:36 +0200 +Subject: Re: ext3 filesystem / linux 7.3 +From: Andreas Kostyrka +To: "Jeffrey D. Brower" +Cc: eric soroos , + Shankar K , pgsql-performance@postgresql.org +In-Reply-To: <0a3001c2f92d$c975a490$0b02a8c0@pointhere.net> +References: <26287373.1162931668@[4.42.179.151]> + <1049296398.20242.325.camel@andi-lap> + <0a3001c2f92d$c975a490$0b02a8c0@pointhere.net> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-6Ll2Ced/E9Wr7KB18d4F" +Organization: +Message-Id: <1049298455.21669.333.camel@andi-lap> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 +Date: 02 Apr 2003 17:47:36 +0200 +X-Spam-Status: No, hits=-41.1 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_XIMIAN + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/19 +X-Sequence-Number: 1525 + +--=-6Ll2Ced/E9Wr7KB18d4F +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Wed, 2003-04-02 at 17:37, Jeffrey D. Brower wrote: +> ... and what *exactly* is the difference? +Between what? (how about a bit more context?) + +Andreas +--=20 +Andreas Kostyrka +Josef-Mayer-Strasse 5 +83043 Bad Aibling + +--=-6Ll2Ced/E9Wr7KB18d4F +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (GNU/Linux) + +iD8DBQA+iwYXHJdudm4KnO0RAthMAKChgPKCOqJ37fL9cQW5yuVvVla70ACbBJ4G +kPOaBDTkD7fyJlJ0EohIQFU= +=7cIv +-----END PGP SIGNATURE----- + +--=-6Ll2Ced/E9Wr7KB18d4F-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 10:57:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 757A7475F16 + for ; + Wed, 2 Apr 2003 10:57:15 -0500 (EST) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 7E537475E91 + for ; + Wed, 2 Apr 2003 10:56:44 -0500 (EST) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 190kbZ-000418-00 + for ; Wed, 02 Apr 2003 10:56:49 -0500 +Received: by dba2 (Postfix, from userid 1019) + id 1F2EBCBAB; Wed, 2 Apr 2003 10:56:49 -0500 (EST) +Date: Wed, 2 Apr 2003 10:56:49 -0500 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Message-ID: <20030402155649.GC15624@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> + <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> + <20030401175519.GA9553@mail> <1049296706.20242.331.camel@andi-lap> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <1049296706.20242.331.camel@andi-lap> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/20 +X-Sequence-Number: 1526 + +On Wed, Apr 02, 2003 at 05:18:26PM +0200, Andreas Kostyrka wrote: + +> Well, I've been using ReiserFS now for years, and never had any problems +> with it. + +Me too. But the "known failure modes" that people keep reporting +about have to do with completely trashing, say, a whole page of data. +Your directories are fine, but the data is all hosed. + +I've never had it happen. I've never seen anyone who can +consistently reproduce it. But I've certainly read about it often +enough to have pretty serious reservations about relying on the +filesystem for data I can't afford to lose. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 11:45:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8A681474E44 + for ; + Wed, 2 Apr 2003 11:45:44 -0500 (EST) +Received: from smtp.web.de (smtp01.web.de [217.72.192.180]) + by postgresql.org (Postfix) with ESMTP id 08C4347630B + for ; + Wed, 2 Apr 2003 11:45:42 -0500 (EST) +Received: from p5081806a.dip0.t-ipconnect.de ([80.129.128.106] helo=web.de) + by smtp.web.de with asmtp (TLSv1:RC4-MD5:128) (WEB.DE(Exim) 4.97 #53) + id 190lMw-0003K5-00 + for pgsql-performance@postgresql.org; Wed, 02 Apr 2003 18:45:46 +0200 +Message-ID: <3E8B13BA.6000208@web.de> +Date: Wed, 02 Apr 2003 18:45:46 +0200 +From: Andreas Pflug +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> + <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> + <20030401175519.GA9553@mail> <1049296706.20242.331.camel@andi-lap> + <20030402155649.GC15624@libertyrms.info> +In-Reply-To: <20030402155649.GC15624@libertyrms.info> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-21.4 required=5.0 + tests=BAYES_01,IN_REP_TO,RCVD_IN_NJABL,REFERENCES, + USER_AGENT_MOZILLA_UA autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/21 +X-Sequence-Number: 1527 + +Are there any comments on JFS regarding real-life safety and speed? + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 12:01:01 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 23C6D476083 + for ; + Wed, 2 Apr 2003 12:01:00 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id C1EF1475ED4 + for ; + Wed, 2 Apr 2003 12:00:58 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h32GoE905563; + Wed, 2 Apr 2003 11:50:15 -0500 +Message-ID: <0a6f01c2f93a$6907bf50$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Andreas Kostyrka" +Cc: "Bruce Momjian" , + , "Shankar K" , + "eric soroos" +References: <26287373.1162931668@[4.42.179.151]> + <1049296398.20242.325.camel@andi-lap> + <0a3001c2f92d$c975a490$0b02a8c0@pointhere.net> + <1049298455.21669.333.camel@andi-lap> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 12:07:57 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-11.2 required=5.0 + tests=BAYES_20,QUOTED_EMAIL_TEXT,RCVD_IN_NJABL,REFERENCES, + X_NJABL_OPEN_PROXY autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/22 +X-Sequence-Number: 1528 + +>> This would indicate that the PG transactioning is complimentary to the +filesystem journaling, not duplication. + +>It's both. See the -o data=journal|data=ordered|data=writeback mount +>time option. + +I did a RTFM on that but I am now confused again. + +I am wondering what the *best* setting is with ext3. When I RTFM the man +page for mount, the data=writeback option says plainly that it is fastest +but in a crash old data is quite possibly on the dataset. The safest +*looks* to be data=journal since the journaling happens before writes are +committed to the file (and presumably the journal is used to update the file +on the disk to apply the journal entry to the disk file?) and the default is +data=ordered which says write to the disk AND THEN to the journal (which +seems bizarre to me). + +How all of that works WITH and/or AGAINST PostgreSQL and what metadata +REALLY means is my bottom line quandary. Obviously that is where finding +the warm and fuzzy place between speed and safety is found. + + Jeff + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 15:05:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4F5CF4762D7 + for ; + Wed, 2 Apr 2003 15:05:44 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 8A3F94762F6 + for ; + Wed, 2 Apr 2003 15:05:39 -0500 (EST) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2938646; Wed, 02 Apr 2003 12:05:26 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Jeffrey D. Brower" , + "Andreas Kostyrka" +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 12:05:30 -0800 +User-Agent: KMail/1.4.3 +Cc: "Bruce Momjian" , + , "Shankar K" , + "eric soroos" +References: <26287373.1162931668@[4.42.179.151]> + <1049298455.21669.333.camel@andi-lap> + <0a6f01c2f93a$6907bf50$0b02a8c0@pointhere.net> +In-Reply-To: <0a6f01c2f93a$6907bf50$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304021205.30075.josh@agliodbs.com> +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/23 +X-Sequence-Number: 1529 + +Jeff, + +> How all of that works WITH and/or AGAINST PostgreSQL and what metadata +> REALLY means is my bottom line quandary. Obviously that is where finding +> the warm and fuzzy place between speed and safety is found. + +For your $PGDATA directory, your only need for filesystem journaling is to= +=20 +prevent a painful fsck process on an unexpected power-out. You are not, as= + a=20 +rule, terribly concerned with journaling the data as PostgreSQL already=20 +provides some data recovery protection through WAL. + +As a result, on my one server where I have to use Ext3 (I use Reiser on mos= +t=20 +machines, and have never had a problem except for one disaster when upgradi= +ng=20 +Reiser versions), the $PGDATA is mounted "noatime,data=3Dwriteback" + +(BTW, I found that combining "data=3Dwriteback" with Linux LVM on RedHat 8.= +0=20 +resulted in system-fatal mounting errors. Anyone else have this problem?) + +Of course, if you have a machine with a $60,000 disk array and disk I/O is= +=20 +unlimited, then maybe you want to enable data=3Djournal just for the protec= +tion=20 +against corruption of the WAL and clog files.=20=20=20 + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 19:23:07 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 108394762A2 + for ; + Wed, 2 Apr 2003 19:23:06 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id BF2A24762D7 + for ; + Wed, 2 Apr 2003 19:23:04 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h330CE906997; + Wed, 2 Apr 2003 19:12:14 -0500 +Message-ID: <0a8001c2f978$28959a80$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: , "Andreas Kostyrka" +Cc: "Bruce Momjian" , + , "Shankar K" , + "eric soroos" +References: <26287373.1162931668@[4.42.179.151]> + <1049298455.21669.333.camel@andi-lap> + <0a6f01c2f93a$6907bf50$0b02a8c0@pointhere.net> + <200304021205.30075.josh@agliodbs.com> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 19:29:57 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-16.9 required=5.0 + tests=BAYES_20,MAILTO_TO_SPAM_ADDR,ORIGINAL_MESSAGE, + QUOTED_EMAIL_TEXT,RCVD_IN_NJABL,REFERENCES, X_NJABL_OPEN_PROXY + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/24 +X-Sequence-Number: 1530 + +Thanks for that Josh. + +I had previously understood that ext3 was a bad thing with PostgreSQL and I +went way above and beyond to create it on an Ext2 filesystem (the only one +on the server) and mount that. + +Should I undo that work and go back to Ext3? + + Jeff + +----- Original Message ----- +From: "Josh Berkus" +To: "Jeffrey D. Brower" ; "Andreas Kostyrka" + +Cc: "Bruce Momjian" ; +; "Shankar K" ; "eric +soroos" +Sent: Wednesday, April 02, 2003 3:05 PM +Subject: Re: [PERFORM] ext3 filesystem / linux 7.3 + + +> Jeff, +> +> > How all of that works WITH and/or AGAINST PostgreSQL and what metadata +> > REALLY means is my bottom line quandary. Obviously that is where +finding +> > the warm and fuzzy place between speed and safety is found. +> +> For your $PGDATA directory, your only need for filesystem journaling is to +> prevent a painful fsck process on an unexpected power-out. You are not, +as a +> rule, terribly concerned with journaling the data as PostgreSQL already +> provides some data recovery protection through WAL. +> +> As a result, on my one server where I have to use Ext3 (I use Reiser on +most +> machines, and have never had a problem except for one disaster when +upgrading +> Reiser versions), the $PGDATA is mounted "noatime,data=writeback" +> +> (BTW, I found that combining "data=writeback" with Linux LVM on RedHat 8.0 +> resulted in system-fatal mounting errors. Anyone else have this +problem?) +> +> Of course, if you have a machine with a $60,000 disk array and disk I/O is +> unlimited, then maybe you want to enable data=journal just for the +protection +> against corruption of the WAL and clog files. +> +> -- +> -Josh Berkus +> Aglio Database Solutions +> San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 19:47:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9FE8C47631B + for ; + Wed, 2 Apr 2003 19:46:53 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id E38B947631B + for ; + Wed, 2 Apr 2003 19:46:38 -0500 (EST) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2939157; Wed, 02 Apr 2003 16:46:33 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Jeffrey D. Brower" +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 16:46:36 -0800 +User-Agent: KMail/1.4.3 +Cc: +References: <26287373.1162931668@[4.42.179.151]> + <200304021205.30075.josh@agliodbs.com> + <0a8001c2f978$28959a80$0b02a8c0@pointhere.net> +In-Reply-To: <0a8001c2f978$28959a80$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304021646.36965.josh@agliodbs.com> +X-Spam-Status: No, hits=-22.7 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/25 +X-Sequence-Number: 1531 + +Jeff, + +> Thanks for that Josh. + +Welcome + +> I had previously understood that ext3 was a bad thing with PostgreSQL and= + I +> went way above and beyond to create it on an Ext2 filesystem (the only one +> on the server) and mount that. +>=20 +> Should I undo that work and go back to Ext3? + +I would. Not necessarily Ext3, mind you; you might want to consider Reiser= + or=20 +JFS, too. My experience has been better with Reiser than Ext3 with Postgre= +s,=20 +but I can't back that up with any statistics. + +(DISCLAIMER: This is not professional advice, and comes with no warranty. = + If=20 +you want professional advice, pay me.) + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 21:44:40 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BDE5247592C + for ; + Wed, 2 Apr 2003 21:44:39 -0500 (EST) +Received: from moya.trilug.org (moya.trilug.org [64.244.27.141]) + by postgresql.org (Postfix) with ESMTP id D3A11474E44 + for ; + Wed, 2 Apr 2003 21:44:38 -0500 (EST) +Received: from trilug.org (pcp01389159pcs.walngs01.pa.comcast.net + [68.80.176.197]) + (using SSLv3 with cipher DES-CBC3-SHA (168/168 bits)) + (No client certificate requested) + by moya.trilug.org (Postfix) with ESMTP id C25A2A0018 + for ; + Wed, 2 Apr 2003 21:44:42 -0500 (EST) +Date: Wed, 2 Apr 2003 21:44:31 -0500 +Subject: Re: ext3 filesystem / linux 7.3 +Content-Type: multipart/signed; protocol="application/pgp-signature"; + micalg=pgp-sha1; boundary="Apple-Mail-1-163718617" +Mime-Version: 1.0 (Apple Message framework v551) +From: Chris Hedemark +To: +Content-Transfer-Encoding: 7bit +In-Reply-To: <093201c2f88f$45e60730$0b02a8c0@pointhere.net> +Message-Id: <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> +X-Request-Pgp: http://yonderway.com/chris/hedemark.gpg +X-Pgp-Agent: GPGMail 0.5.4 (v22 Jaguar) +X-Mailer: Apple Mail (2.551) +X-Spam-Status: No, hits=-24.9 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + USER_AGENT_APPLEMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/26 +X-Sequence-Number: 1532 + +--Apple-Mail-1-163718617 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII; format=flowed + + +On Tuesday, April 1, 2003, at 03:42 PM, Jeffrey D. Brower wrote: + +> OK so am I hearing: + +Enough... + +...there is waaay too much hearsay going on in this thread. Let's come +up with an acceptable test battery and actually settle it once and for +all with good hard numbers. It would be worth my while to spend some +time on this since the developers I support currently hate pgsql due to +performance complaints (on servers that predate my employment there). +So if I am going to move them to better servers it would be worth my +while to do some homework on what OS and FS is best. + +I'm not qualified at all to define the tests. I am willing to try it +on any OS that will run on a Sun Ultra 5, which would include Linux, +several BSD's and Solaris to name a few. It also runs the gammut of +filesystems that have been talked about here. The machine isn't a +barnstormer but I'm willing to put in an 18GB SCSI drive and try this +with many different OS's and FS's if someone qualified will put +together an acceptable test suite and it doesn't meet with too much +opposition by the gurus here. + +The test machine: + + Sun UltraSPARC 5 + 333MHz UltraSPARC CPU, 2MB cache + 256MB RAM + whatever SCSI card I can find most quickly + either a 9GB or 18GB SCSI drive (whichever I can find most quickly) + +The test client would likely be an Apple Powerbook G4 800MHz, 512MB, +running OS X 10.2.4. Yes the client runs rings around the server but I +can afford to abuse the server. + +While the server is admittedly an older machine, for the purpose of +this test it should not matter as long as the hardware configuration is +equal for all tests. If we agree on a test suite there is nothing to +stop someone from running the same suite on their own hardware and +reporting their own results. + +Anyone game to give a go at this? + +-- + +"What difference does it make to the dead, the orphans and the +homeless, whether the mad destruction is wrought under the name of +totalitarianism or the holy name of liberty or democracy?" - Mahatma +Gandhi + +--Apple-Mail-1-163718617 +content-type: application/pgp-signature; x-mac-type=70674453; + name=PGP.sig +content-disposition: inline +content-transfer-encoding: 7bit + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (Darwin) + +iEYEARECAAYFAj6LoBcACgkQYPuF4Zq9lvZoNgCgnHWhAbqErMYD26dsLHHU3b0x +PHsAn3qSsrg8qykl0hb8GCXFRhkjCwN/ +=fh7+ +-----END PGP SIGNATURE----- + +--Apple-Mail-1-163718617-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 2 21:58:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 25CAC475ED4 + for ; + Wed, 2 Apr 2003 21:58:13 -0500 (EST) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 81309475CEE + for ; + Wed, 2 Apr 2003 21:58:12 -0500 (EST) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 190uvg-0004zW-00 + for ; Wed, 02 Apr 2003 21:58:16 -0500 +Received: by dba2 (Postfix, from userid 1019) + id BA781CC11; Wed, 2 Apr 2003 21:58:16 -0500 (EST) +Date: Wed, 2 Apr 2003 21:58:16 -0500 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Message-ID: <20030403025816.GA17411@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: <093201c2f88f$45e60730$0b02a8c0@pointhere.net> + <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/27 +X-Sequence-Number: 1533 + +On Wed, Apr 02, 2003 at 09:44:31PM -0500, Chris Hedemark wrote: + +> While the server is admittedly an older machine, for the purpose of +> this test it should not matter as long as the hardware configuration is +> equal for all tests. If we agree on a test suite there is nothing to + +That's false. + +One of the big problems with a lot of tuning info is that it tends +not to take int consideration hardware, &c. I can tell you for sure +that if you have a giant-cache array connected by fibre channel, _it +makes no difference_ what the filesystem is. The array is so fast +that you can't really fill the cache under normal load anyway. +Similarly, if you have enough memory, every read test is going to be +as fast as any other: you'll get 100% cache hits, and the same memory +configured the same way will always respond at about the same speed. + +That said, I think you're right to demand some tests, and to say that +holding the machine constant and changing filesystems is a good +filesystem test. + +So here are some suggested things, in no real order: + +1. Make sure you run out of buffers before you start to read +(for read filesystem speed tests). +2. Pull the power plug repeatedly while the server is under +load. Judge robustness. +3. Put WAL and data area on different filesystems (to be fair, +this should probably be different spindles, but I'll take what I can +get) and configure the filesystems in various ways (including, say, +writeback for data and full journalling for WAL). See tests above. +4. Make sure your controller doesn't lie about fsync. +5. Test under different loads. 10% writes vs. 90% reads; +20% writes; &c. Compare simple INSERT write with UPDATE write. +Compare UPDATE writes where the UPDATEd row is the same one over and +over. Make sure you do (2) several times. + +Lots of these are artificial. But it seems they might reveal +something. I'd be particularly keen to hear about what _really_ is +up with reiserfs. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 00:34:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4B66F4763A7 + for ; + Thu, 3 Apr 2003 00:34:03 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 7B81C4763AB + for ; + Thu, 3 Apr 2003 00:33:51 -0500 (EST) +Received: from [63.195.55.98] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2939505; Wed, 02 Apr 2003 21:33:45 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Chris Hedemark , + +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 2 Apr 2003 21:33:44 -0800 +User-Agent: KMail/1.4.3 +References: <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> +In-Reply-To: <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304022133.44511.josh@agliodbs.com> +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/28 +X-Sequence-Number: 1534 + +Chris, + +> ...there is waaay too much hearsay going on in this thread. Let's come= +=20 +> up with an acceptable test battery and actually settle it once and for=20 +> all with good hard numbers. It would be worth my while to spend some=20 +> time on this since the developers I support currently hate pgsql due to= +=20 +> performance complaints (on servers that predate my employment there).=20= +=20 +> So if I am going to move them to better servers it would be worth my=20 +> while to do some homework on what OS and FS is best. + +You're not going to be able to determine this for certain, but at least you= +=20 +should be able to debunk some myths. Here's my suggested tests: + +1) Read-only test -- numerous small rapidfire queries in the fashion of a P= +HP=20 +web application. PGBench already does this one test ok, maybe you could us= +e=20 +that. + +2) Complex query test -- run a few 12-table queries with CASE statements,= +=20 +custom functions and subselects and/or UNIONs.=20=20=20 + +3) Transaction Test -- hit the database with numerous rapid-fire single row= +=20 +updates to a few tables. + +4) OLAP Test -- do a few massive updates to thousands of rows based on rela= +ted=20 +data and/or cascading updates to multiple tables and dozens-hundreds of row= +s.=20=20 +Create large temp tables based on Joe Conway's Crosstab. + +5) Mixed use test: combine 1, 2, & 3 in a ratio of 70% 10% 20% on several= +=20 +simultaneous connections. + +Of course this requires us to have a sample database with at least 100,000= +=20 +rows of data in one or two tables plus at least 5-10 additional tables with= +=20 +realistically complex relationships. Donor, anyone? + +Also, we'll have to talk about .conf files ... + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 00:46:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E64BE475ED4 + for ; + Thu, 3 Apr 2003 00:46:48 -0500 (EST) +Received: from martin.sysdetect.com (martin.sysdetect.com [65.209.102.1]) + by postgresql.org (Postfix) with ESMTP id 2A30B475CEE + for ; + Thu, 3 Apr 2003 00:46:48 -0500 (EST) +Received: (from mail@localhost) + by martin.sysdetect.com (8.11.3/8.11.3) id h335kpO17044; + Thu, 3 Apr 2003 05:46:51 GMT +Received: from winwood.sysdetect.com(172.16.1.1) + via SMTP by mail.sysdetect.com, id smtpdA10554; Thu Apr 3 05:46:48 2003 +Received: from winwood.sysdetect.com (seth@localhost) + by winwood.sysdetect.com (8.11.6/8.11.6) with ESMTP id h335kmQ20311; + Thu, 3 Apr 2003 00:46:48 -0500 +Message-Id: <200304030546.h335kmQ20311@winwood.sysdetect.com> +To: josh@agliodbs.com +Cc: Chris Hedemark , + pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +In-reply-to: <200304022133.44511.josh@agliodbs.com> +References: <322CCBF8-657E-11D7-8752-0003939CC61E@trilug.org> + <200304022133.44511.josh@agliodbs.com> +Comments: In reply to a message from "Josh Berkus " dated + "Wed, 02 Apr 2003 21:33:44 -0800." +Date: Thu, 03 Apr 2003 00:46:48 -0500 +From: Seth Robertson +X-Spam-Status: No, hits=-27.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,MSG_ID_ADDED_BY_MTA_3, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/29 +X-Sequence-Number: 1535 + + +In message <200304022133.44511.josh@agliodbs.com>, Josh Berkus writes: + + Chris, + + > ...there is waaay too much hearsay going on in this thread. Let's come + > up with an acceptable test battery and actually settle it once and for + > all with good hard numbers. It would be worth my while to spend some + > time on this since the developers I support currently hate pgsql due to + > performance complaints (on servers that predate my employment there). + > So if I am going to move them to better servers it would be worth my + > while to do some homework on what OS and FS is best. + + You're not going to be able to determine this for certain, but at + least you should be able to debunk some myths. Here's my + suggested tests: + + [...] + + Also, we'll have to talk about .conf files ... + +When I installed my postgres, I tried a test program I wrote with all +four values of wal_sync, and for my RedHat Linux 8.0 ext3 filesystem +(default mount options), and my toy test; open_sync performed the best +for me. Thus, I would suggest adding the wal_sync_method as another +axis for your testing. + + -Seth Robertson + seth@sysd.com + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 05:58:04 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9B863475CEE + for ; + Thu, 3 Apr 2003 05:58:02 -0500 (EST) +Received: from moya.trilug.org (moya.trilug.org [64.244.27.141]) + by postgresql.org (Postfix) with ESMTP id CDFAA475C3D + for ; + Thu, 3 Apr 2003 05:58:01 -0500 (EST) +Received: from trilug.org (pcp01389159pcs.walngs01.pa.comcast.net + [68.80.176.197]) + (using SSLv3 with cipher DES-CBC3-SHA (168/168 bits)) + (No client certificate requested) + by moya.trilug.org (Postfix) with ESMTP id D75BCA0027 + for ; + Thu, 3 Apr 2003 05:58:03 -0500 (EST) +Date: Thu, 3 Apr 2003 05:58:01 -0500 +Subject: Re: ext3 filesystem / linux 7.3 +Content-Type: text/plain; charset=US-ASCII; format=flowed +Mime-Version: 1.0 (Apple Message framework v551) +From: Chris Hedemark +To: +Content-Transfer-Encoding: 7bit +In-Reply-To: <200304022133.44511.josh@agliodbs.com> +Message-Id: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> +X-Request-Pgp: http://yonderway.com/chris/hedemark.gpg +X-Mailer: Apple Mail (2.551) +X-Spam-Status: No, hits=-28.3 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_APPLEMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/30 +X-Sequence-Number: 1536 + + +On Thursday, April 3, 2003, at 12:33 AM, Josh Berkus wrote: + +> You're not going to be able to determine this for certain, but at +> least you +> should be able to debunk some myths. Here's my suggested tests: +[snip] + +Being a mere sysadmin, it is creation of the test cases (perl script, +maybe?) that I'll have to ask someone else with more of a development +bent to help with. My talent is more along the lines of system +administration. Plus I am willing to take the time to go through these +tests over & over with a different OS or different tuning parameters on +the same OS, different FS's, etc. Someone else needs to come up with +the test code. The client machine has pgsql on it also if the results +are going into a db that won't go away after every test. :) + +-- + +"What difference does it make to the dead, the orphans and the +homeless, whether the mad destruction is wrought under the name of +totalitarianism or the holy name of liberty or democracy?" - Mahatma +Gandhi + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 11:08:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id F0F18475CEE + for ; + Thu, 3 Apr 2003 11:08:44 -0500 (EST) +Received: from irko.smoothcorp.com (unknown [208.49.241.41]) + by postgresql.org (Postfix) with ESMTP id 4BF07475CE5 + for ; + Thu, 3 Apr 2003 11:08:44 -0500 (EST) +Received: from taurus.ifloor.com ([10.0.1.20] helo=taurus.smoothcorp.com) + by irko.smoothcorp.com with esmtp (Exim 4.12) id 1917Gi-00015l-00 + for pgsql-performance@postgresql.org; Thu, 03 Apr 2003 08:08:48 -0800 +Received: from localhost (chris@localhost) + by taurus.smoothcorp.com (8.11.6/8.11.6) with ESMTP id h33G8kM14087 + for ; Thu, 3 Apr 2003 08:08:46 -0800 +X-Authentication-Warning: taurus.smoothcorp.com: chris owned process doing -bs +Date: Thu, 3 Apr 2003 08:08:46 -0800 (PST) +From: Chris Sutton +To: pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +In-Reply-To: <200304021646.36965.josh@agliodbs.com> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-SA-Exim-Rcpt-To: pgsql-performance@postgresql.org +X-SA-Exim-Scanned: No; SAEximRunCond expanded to false +X-Spam-Status: No, hits=-24.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTE_TWICE_1, + USER_AGENT_PINE,X_AUTH_WARNING autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/31 +X-Sequence-Number: 1537 + +On Wed, 2 Apr 2003, Josh Berkus wrote: + +> > I had previously understood that ext3 was a bad thing with PostgreSQL and I +> > went way above and beyond to create it on an Ext2 filesystem (the only one +> > on the server) and mount that. + +We recently started using Postgres on a new database server running RH 7.3 +and ext3. Due to some kernel problems the machine would crash at random +times. Each time it crashed it came back up extremly easily with no data +loss. If we were on ext2 coming back up after a crash probably wouldn't +have been quite as easy. + +We have since given up on RH 7.3 and gone with RH Enterprise ES. Just an +FIY for any of you out there thinking about moving to RH 7.3 or those that +are having problems with 7.3 and ext3. + +Chris + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 11:52:40 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B6D83474E4F + for ; + Thu, 3 Apr 2003 11:52:38 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 74826474E44 + for ; + Thu, 3 Apr 2003 11:52:37 -0500 (EST) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2940289; Thu, 03 Apr 2003 08:52:35 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Chris Hedemark , + +Subject: Re: ext3 filesystem / linux 7.3 +Date: Thu, 3 Apr 2003 08:52:34 -0800 +User-Agent: KMail/1.4.3 +References: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> +In-Reply-To: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> +MIME-Version: 1.0 +Message-Id: <200304030852.34194.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-28.9 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/32 +X-Sequence-Number: 1538 + +Chris, + +> Being a mere sysadmin, it is creation of the test cases (perl script, +> maybe?) that I'll have to ask someone else with more of a development +> bent to help with.=20=20 + +I'll write the test queries and perl scripts if someone else can supply the= +=20 +database. Unfortunately, while I have a few databases that meet the=20 +criteria, they are all NDA.=20=20=20 + +Criteria again: +Must have at least 100,000 rows with 12+ columns in "main" table. +Must have at least 10-12 additional tables, some with FK relationships to t= +he=20 +main table and each other. +Must be OK to make contents public. +More is better up to 500MB. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 11:59:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 56FE0474E44 + for ; + Thu, 3 Apr 2003 11:59:43 -0500 (EST) +Received: from moya.trilug.org (moya.trilug.org [64.244.27.141]) + by postgresql.org (Postfix) with ESMTP id BFDAF474E4F + for ; + Thu, 3 Apr 2003 11:59:42 -0500 (EST) +Received: from trilug.org (vpn.ccgroupnet.com [207.103.85.62]) + (using SSLv3 with cipher DES-CBC3-SHA (168/168 bits)) + (No client certificate requested) + by moya.trilug.org (Postfix) with ESMTP id 9EBF5A0027 + for ; + Thu, 3 Apr 2003 11:59:47 -0500 (EST) +Date: Thu, 3 Apr 2003 11:59:44 -0500 +Subject: Re: ext3 filesystem / linux 7.3 +Content-Type: text/plain; charset=US-ASCII; format=flowed +Mime-Version: 1.0 (Apple Message framework v551) +From: Chris Hedemark +To: +Content-Transfer-Encoding: 7bit +In-Reply-To: <200304030852.34194.josh@agliodbs.com> +Message-Id: +X-Request-Pgp: http://yonderway.com/chris/hedemark.gpg +X-Mailer: Apple Mail (2.551) +X-Spam-Status: No, hits=-18.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,USER_AGENT_APPLEMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/33 +X-Sequence-Number: 1539 + + +On Thursday, April 3, 2003, at 11:52 AM, Josh Berkus wrote: + +> Unfortunately, while I have a few databases that meet the +> criteria, they are all NDA. + +I'm in the same boat. + +-- + +"What difference does it make to the dead, the orphans and the +homeless, whether the mad destruction is wrought under the name of +totalitarianism or the holy name of liberty or democracy?" - Mahatma +Gandhi + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 12:04:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E26B0474E4F + for ; + Thu, 3 Apr 2003 12:04:42 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id 4B54F47636C + for ; + Thu, 3 Apr 2003 12:04:40 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h33GsV910691; + Thu, 3 Apr 2003 11:54:32 -0500 +Message-ID: <0b7a01c2fa04$2d299bf0$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Josh Berkus" , "Chris Hedemark" , + +References: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> + <200304030852.34194.josh@agliodbs.com> +Subject: Re: ext3 filesystem / linux 7.3 +Date: Thu, 3 Apr 2003 12:12:16 -0500 +Organization: Green Visor, Inc. +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-17.5 required=5.0 + tests=BAYES_20,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,RCVD_IN_NJABL, + REFERENCES,X_NJABL_OPEN_PROXY autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/34 +X-Sequence-Number: 1540 + +Can't we generate data? Random data stored in random formats at random +sizes would stress the file system wouldn't it? + +----- Original Message ----- +From: "Josh Berkus" +To: "Chris Hedemark" ; +Sent: Thursday, April 03, 2003 11:52 AM +Subject: Re: [PERFORM] ext3 filesystem / linux 7.3 + + +> Chris, +> +> > Being a mere sysadmin, it is creation of the test cases (perl script, +> > maybe?) that I'll have to ask someone else with more of a development +> > bent to help with. +> +> I'll write the test queries and perl scripts if someone else can supply +the +> database. Unfortunately, while I have a few databases that meet the +> criteria, they are all NDA. +> +> Criteria again: +> Must have at least 100,000 rows with 12+ columns in "main" table. +> Must have at least 10-12 additional tables, some with FK relationships to +the +> main table and each other. +> Must be OK to make contents public. +> More is better up to 500MB. +> +> -- +> Josh Berkus +> Aglio Database Solutions +> San Francisco +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 13:00:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CFD83476372 + for ; + Thu, 3 Apr 2003 12:43:07 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id D397247635E + for ; + Thu, 3 Apr 2003 12:43:05 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2940377; Thu, 03 Apr 2003 09:43:03 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Jeffrey D. Brower" , + "Chris Hedemark" , +Subject: Re: ext3 filesystem / linux 7.3 +Date: Thu, 3 Apr 2003 09:43:06 -0800 +User-Agent: KMail/1.4.3 +References: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> + <200304030852.34194.josh@agliodbs.com> + <0b7a01c2fa04$2d299bf0$0b02a8c0@pointhere.net> +In-Reply-To: <0b7a01c2fa04$2d299bf0$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304030943.06406.josh@agliodbs.com> +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/37 +X-Sequence-Number: 1543 + +Jeffery, + +> Can't we generate data? Random data stored in random formats at random +> sizes would stress the file system wouldn't it? + +In my experience, randomly generated data tends to resemble real data very= +=20 +little in distribution patterns and data types. This is one of the=20 +limitations of PGBench. + +Surely there must be an OSS project out there with a medium-large PG databa= +se=20 +which is OSS-licensed? + +I'll post on GENERAL + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 12:59:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0FD7F476323 + for ; + Thu, 3 Apr 2003 12:49:43 -0500 (EST) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 564CF476334 + for ; + Thu, 3 Apr 2003 12:49:42 -0500 (EST) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h33Hn1hr029829; + Thu, 3 Apr 2003 10:49:01 -0700 (MST) +Date: Thu, 3 Apr 2003 10:45:50 -0700 (MST) +From: "scott.marlowe" +To: Chris Sutton +Cc: +Subject: Re: ext3 filesystem / linux 7.3 +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-21.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/36 +X-Sequence-Number: 1542 + +On Thu, 3 Apr 2003, Chris Sutton wrote: + +> On Wed, 2 Apr 2003, Josh Berkus wrote: +> +> > > I had previously understood that ext3 was a bad thing with PostgreSQL and I +> > > went way above and beyond to create it on an Ext2 filesystem (the only one +> > > on the server) and mount that. +> +> We recently started using Postgres on a new database server running RH 7.3 +> and ext3. Due to some kernel problems the machine would crash at random +> times. Each time it crashed it came back up extremly easily with no data +> loss. If we were on ext2 coming back up after a crash probably wouldn't +> have been quite as easy. +> +> We have since given up on RH 7.3 and gone with RH Enterprise ES. Just an +> FIY for any of you out there thinking about moving to RH 7.3 or those that +> are having problems with 7.3 and ext3. + +We're still running RH 7.2 due to issues we had with 7.3 as well. + + +From pgsql-general-owner@postgresql.org Thu Apr 3 12:59:35 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id DE269475B47; Thu, 3 Apr 2003 12:55:16 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id 0BCFB474E44; Thu, 3 Apr 2003 12:55:16 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2940404; Thu, 03 Apr 2003 09:55:14 -0800 +Content-Type: text/plain; + charset="us-ascii" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: pgsql-general@postgresql.org, pgsql-performance@postgresql.org, + pgsql-hackers@postgresql.org +Subject: OSS database needed for testing +Date: Thu, 3 Apr 2003 09:55:16 -0800 +User-Agent: KMail/1.4.3 +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304030955.16543.josh@agliodbs.com> +X-Spam-Status: No, hits=-12.2 required=5.0 tests=BAYES_10,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/224 +X-Sequence-Number: 40289 + +Folks, + +Please pardon the cross-posting. + +A small group of us on the Performance list were discussing the first steps= +=20 +toward constructing a comprehensive Postgresql installation benchmarking=20 +tool, mostly to compare different operating systems and file systemsm but= +=20 +later to be used as a foundation for a tuning wizard.=20=20=20 + +To do this, we need one or more real (not randomly generated*) medium-large= +=20 +database which is or can be BSD-licensed (data AND schema). This database= +=20 +must have: + +1) At least one "main" table with 12+ columns and 100,000+ rows (each). +2) At least 10-12 additional tables of assorted sizes, at least half of whi= +ch=20 +should have Foriegn Key relationships to the main table(s) or each other. +3) At least one large text or varchar field among the various tables. + +In addition, the following items would be helpful, but are not required: +4) Views, triggers, and functions built on the database +5) A query log of database activity to give us sample queries to work with. +6) Some complex data types, such as geometric, network, and/or custom data= +=20 +types. + +Thanks for any leads you can give me! + +(* To forestall knee-jerk responses: Randomly generated data does not look= + or=20 +perform the same as real data in my professional opinion, and I'm the one= +=20 +writing the test scripts.) + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-general-owner@postgresql.org Mon Apr 7 12:40:19 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 0EBBB47632B; Thu, 3 Apr 2003 13:09:00 -0500 (EST) +Received: from cuthbert.rcsinc.local (unknown [205.217.85.84]) + by postgresql.org (Postfix) with ESMTP + id 49A98476326; Thu, 3 Apr 2003 13:08:59 -0500 (EST) +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable +Subject: Re: [HACKERS] OSS database needed for testing +X-MimeOLE: Produced By Microsoft Exchange V6.0.6375.0 +Date: Thu, 3 Apr 2003 13:12:12 -0500 +Message-ID: <303E00EBDD07B943924382E153890E5434A939@cuthbert.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [HACKERS] OSS database needed for testing +Thread-Index: AcL6C8ILN5HzpJkeQAuG0slbQhqdowAABjjg +From: "Merlin Moncure" +To: +Cc: , + , +X-Spam-Status: No, hits=-15.5 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/452 +X-Sequence-Number: 40517 + +Josh Berkus wrote: +> 1) At least one "main" table with 12+ columns and 100,000+ rows +(each). +> 2) At least 10-12 additional tables of assorted sizes, at least half +of +> which +> should have Foriegn Key relationships to the main table(s) or each +other. +> 3) At least one large text or varchar field among the various tables. +>=20 +> In addition, the following items would be helpful, but are not +required: +> 4) Views, triggers, and functions built on the database +> 5) A query log of database activity to give us sample queries to work +> with. +> 6) Some complex data types, such as geometric, network, and/or custom +data +> types. +>=20 +Might I recommend the FCC database of transmitters. Its publicly +available via anonymous FTP, medium largish with tables running 100k -> +1m+ records, and demonstrates many interesting test cases. For example, +lat/lon spatial queries (RTree vs. GIST) can be tested with a decent +volume. Also it demonstrates a good example of the use of schemas. +Email me if you want info. + +Format is pipe delimited (non quoted), and data turnover is < 1% a week. + +Merlin + + +From pgsql-general-owner@postgresql.org Mon Apr 7 12:21:47 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id E0789476237; Thu, 3 Apr 2003 13:15:37 -0500 (EST) +Received: from outland.mohawksoft.com (unknown [64.46.156.80]) + by postgresql.org (Postfix) with ESMTP + id B6B8B475D3B; Thu, 3 Apr 2003 13:15:32 -0500 (EST) +Received: from mohawksoft.com (outland.mohawksoft.com [127.0.0.1]) + by outland.mohawksoft.com (8.11.6/8.9.3) with SMTP id h33IQ1f01853; + Thu, 3 Apr 2003 13:26:01 -0500 +From: pgsql@mohawksoft.com +Received: from 141.154.39.187 (SquirrelMail authenticated user pgsql) + by mail.mohawksoft.com with HTTP; + Thu, 3 Apr 2003 13:26:01 -0500 (EST) +Message-ID: <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> +Date: Thu, 3 Apr 2003 13:26:01 -0500 (EST) +Subject: Re: [HACKERS] OSS database needed for testing +To: josh@agliodbs.com +In-Reply-To: <200304030955.16543.josh@agliodbs.com> +References: <200304030955.16543.josh@agliodbs.com> +Cc: pgsql-general@postgresql.org, pgsql-performance@postgresql.org, + pgsql-hackers@postgresql.org +X-Mailer: SquirrelMail (version 1.0.6) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-24.2 required=5.0 + tests=BAYES_10,IN_REP_TO,NO_REAL_NAME,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/430 +X-Sequence-Number: 40495 + +I don't know that it meets your criteria, but..... + +I have a set of scripts and a program that will load the US Census TigerUA +database into PostgreSQL. The thing is absolutely freak'n huge. I forget +which, but it is either 30g or 60g of data excluding indexes. + +Also, if that is too much, I have a similar setup to load the FreeDB music +database, from www.freedb.org. It has roughly 670,000 entries in "cdtitles" +and 8 million entries in "cdsongs." + +Either one of which, I would be willing to send you the actual DB on cd(s) +if you pay for postage and media.=20 +=20 + +> Folks, +>=20 +> Please pardon the cross-posting. +>=20 +> A small group of us on the Performance list were discussing the first +> steps toward constructing a comprehensive Postgresql installation +> benchmarking tool, mostly to compare different operating systems and +> file systemsm but later to be used as a foundation for a tuning +> wizard.=20=20=20 +>=20 +> To do this, we need one or more real (not randomly generated*) +> medium-large database which is or can be BSD-licensed (data AND +> schema). This database must have: +>=20 +> 1) At least one "main" table with 12+ columns and 100,000+ rows (each). +> 2) At least 10-12 additional tables of assorted sizes, at least half of +> which should have Foriegn Key relationships to the main table(s) or +> each other. 3) At least one large text or varchar field among the +> various tables. +>=20 +> In addition, the following items would be helpful, but are not +> required: 4) Views, triggers, and functions built on the database +> 5) A query log of database activity to give us sample queries to work +> with. 6) Some complex data types, such as geometric, network, and/or +> custom data types. +>=20 +> Thanks for any leads you can give me! +>=20 +> (* To forestall knee-jerk responses: Randomly generated data does not +> look or perform the same as real data in my professional opinion, and +> I'm the one writing the test scripts.) +>=20 +> --=20 +> -Josh Berkus +> Aglio Database Solutions +> San Francisco +>=20 +>=20 +> ---------------------------(end of +> broadcast)--------------------------- TIP 1: subscribe and unsubscribe +> commands go to majordomo@postgresql.org + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 14:45:55 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3FE1547636C + for ; + Thu, 3 Apr 2003 14:45:53 -0500 (EST) +Received: from web21103.mail.yahoo.com (web21103.mail.yahoo.com + [216.136.227.105]) + by postgresql.org (Postfix) with SMTP id 0DE39476366 + for ; + Thu, 3 Apr 2003 14:45:52 -0500 (EST) +Message-ID: <20030403194552.914.qmail@web21103.mail.yahoo.com> +Received: from [208.253.218.33] by web21103.mail.yahoo.com via HTTP; + Thu, 03 Apr 2003 11:45:52 PST +Date: Thu, 3 Apr 2003 11:45:52 -0800 (PST) +From: Shankar K +Subject: Re: ext3 filesystem / linux 7.3 +To: "scott.marlowe" , + Chris Sutton +Cc: pgsql-performance@postgresql.org +In-Reply-To: +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-9.1 required=5.0 + tests=BAYES_01,FROM_ENDS_IN_NUMS,IN_REP_TO + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/40 +X-Sequence-Number: 1546 + +Hi Scott, + +Could you please share with us the problems you had +with linux 7.3 + +would be really interested to know the kernel configs +and ext3 filesystem modes + +Shankar + +--- "scott.marlowe" wrote: +> On Thu, 3 Apr 2003, Chris Sutton wrote: +> +> > On Wed, 2 Apr 2003, Josh Berkus wrote: +> > +> > > > I had previously understood that ext3 was a +> bad thing with PostgreSQL and I +> > > > went way above and beyond to create it on an +> Ext2 filesystem (the only one +> > > > on the server) and mount that. +> > +> > We recently started using Postgres on a new +> database server running RH 7.3 +> > and ext3. Due to some kernel problems the machine +> would crash at random +> > times. Each time it crashed it came back up +> extremly easily with no data +> > loss. If we were on ext2 coming back up after a +> crash probably wouldn't +> > have been quite as easy. +> > +> > We have since given up on RH 7.3 and gone with RH +> Enterprise ES. Just an +> > FIY for any of you out there thinking about moving +> to RH 7.3 or those that +> > are having problems with 7.3 and ext3. +> +> We're still running RH 7.2 due to issues we had with +> 7.3 as well. +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the +> unregister command +> (send "unregister YourEmailAddressHere" to +majordomo@postgresql.org) + + +__________________________________________________ +Do you Yahoo!? +Yahoo! Tax Center - File online, calculators, forms, and more +http://tax.yahoo.com + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 15:23:01 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 90270475A45 + for ; + Thu, 3 Apr 2003 15:22:59 -0500 (EST) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id BE074474E4F + for ; + Thu, 3 Apr 2003 15:22:55 -0500 (EST) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h33KMNhr014519; + Thu, 3 Apr 2003 13:22:23 -0700 (MST) +Date: Thu, 3 Apr 2003 13:19:10 -0700 (MST) +From: "scott.marlowe" +To: Shankar K +Cc: Chris Sutton , + +Subject: Re: ext3 filesystem / linux 7.3 +In-Reply-To: <20030403194552.914.qmail@web21103.mail.yahoo.com> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-22.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/41 +X-Sequence-Number: 1547 + +On Thu, 3 Apr 2003, Shankar K wrote: + +> Hi Scott, +> +> Could you please share with us the problems you had +> with linux 7.3 +> +> would be really interested to know the kernel configs +> and ext3 filesystem modes + +Actually, I had a couple of problems with it, one of which was that I +couldn't get it to book with ext3 file systems properly. I think it was +something to do with ext3 on linux kernel RAID sets that wouldn't work +right. There's probably a fix for it, but 7.2 is pretty stable, and we +can wait for 8.0 or maybe look at another distro. + +I remember there being some other issues I had with configuration stuff +like this, but now that it's been many months since I played with it I +can't remember them all. + +My personal problem was that redhat stopped including linuxconf as an rpm +package, and the only configuration programs they include don't seem to +work well from a command line, but seemed to prefer to be used in X11. + + +From pgsql-general-owner@postgresql.org Thu Apr 3 16:02:03 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 91AF8475CEE + for ; + Thu, 3 Apr 2003 16:01:56 -0500 (EST) +Received: from wolff.to (wolff.to [66.93.249.74]) + by postgresql.org (Postfix) with SMTP id A9023475A45 + for ; + Thu, 3 Apr 2003 16:01:55 -0500 (EST) +Received: (qmail 31207 invoked by uid 500); 3 Apr 2003 21:01:47 -0000 +Date: Thu, 3 Apr 2003 15:01:47 -0600 +From: Bruno Wolff III +To: pgsql@mohawksoft.com +Cc: josh@agliodbs.com, pgsql-general@postgresql.org, + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing +Message-ID: <20030403210147.GB30860@wolff.to> +Mail-Followup-To: pgsql@mohawksoft.com, josh@agliodbs.com, + pgsql-general@postgresql.org, pgsql-performance@postgresql.org, + pgsql-hackers@postgresql.org +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> +User-Agent: Mutt/1.5.4i +X-Spam-Status: No, hits=-34.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SUSPICIOUS_RECIPS, USER_AGENT_MUTT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/271 +X-Sequence-Number: 40336 + +On Thu, Apr 03, 2003 at 13:26:01 -0500, + pgsql@mohawksoft.com wrote: +> I don't know that it meets your criteria, but..... +> +> I have a set of scripts and a program that will load the US Census TigerUA +> database into PostgreSQL. The thing is absolutely freak'n huge. I forget +> which, but it is either 30g or 60g of data excluding indexes. + +Are the data model or the loading scripts available publicly? +I have the tiger data and a program that uses it to convert addresses +to latitude and longitude, but I don't really like the program and +was thinking about trying to load the data into a database and do +queries against the database to find location. + + +From pgsql-sql-owner@postgresql.org Thu Apr 3 16:02:08 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8372F474E4F + for ; Thu, 3 Apr 2003 16:02:05 -0500 (EST) +Received: from localhost.localdomain (unknown [65.217.53.66]) + by postgresql.org (Postfix) with ESMTP id 93A0B474E44 + for ; Thu, 3 Apr 2003 16:02:04 -0500 (EST) +Received: from thorn.mmrd.com (thorn.mmrd.com [172.25.10.100]) + by localhost.localdomain (8.12.8/8.12.5) with ESMTP id h33LdAkj019039 + for ; Thu, 3 Apr 2003 16:39:10 -0500 +Received: from gnvex001.mmrd.com (gnvex001.mmrd.com [192.168.3.55]) + by thorn.mmrd.com (8.11.6/8.11.6) with ESMTP id h33L24x13931 + for ; Thu, 3 Apr 2003 16:02:05 -0500 +Received: from camel.mmrd.com ([172.25.5.213]) by gnvex001.mmrd.com with SMTP + (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) + id F3HTLZHR; Thu, 3 Apr 2003 16:02:04 -0500 +Subject: can i make this sql query more efficiant? +From: Robert Treat +To: pgsql-sql@postgresql.org +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.8 +Date: 03 Apr 2003 16:02:04 -0500 +Message-Id: <1049403724.13799.5473.camel@camel> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-12.1 required=5.0 tests=BAYES_10,USER_AGENT_XIMIAN + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/52 +X-Sequence-Number: 12753 + + +create table baz (event text, level int); + +insert into baz values ('x',1); +insert into baz values ('x',2); +insert into baz values ('x',3); +insert into baz values ('y',2); +insert into baz values ('y',3); +insert into baz values ('y',3); + +select * from baz; + + event | level +-------+------- + x | 1 + x | 2 + x | 3 + y | 2 + y | 3 + y | 3 +(6 rows) + + +I want to know how many ones, twos, and threes there are for each event: + +select + event, + (select count(*) from baz a + where level = 1 and a.event=baz.event) as ones, + (select count(*) from baz a + where level = 2 and a.event=baz.event) as twos, + (select count(*) from baz a + where level = 3 and a.event=baz.event) as threes +from + baz +group by + event; + +which gives me: + + event | ones | twos | threes +-------+------+------+-------- + x | 1 | 1 | 1 + y | 0 | 1 | 2 +(2 rows) + + +which is fine, but I am wondering if there is a better way to do this? +I'd mainly like to reduce the number of subqueries involved. Another +improvement would be to not have to explicitly query for each level, +though this isn't as big since I know the range of levels in advance +(famous last words for a dba :-) + +Thanks in advance, + +Robert Treat + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 17:05:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C3421475CE5 + for ; + Thu, 3 Apr 2003 17:05:08 -0500 (EST) +Received: from isis.pcis.net (cr.pcis.net [207.18.226.3]) + by postgresql.org (Postfix) with ESMTP id 7F104475ED4 + for ; + Thu, 3 Apr 2003 17:04:37 -0500 (EST) +Received: from lyric.ofsloans.com (unverified [209.180.142.225]) by + isis.pcis.net + (Rockliffe SMTPRA 4.5.6) with ESMTP id ; + Thu, 3 Apr 2003 16:04:24 -0600 +Subject: Re: ext3 filesystem / linux 7.3 +From: Will LaShell +To: "scott.marlowe" +Cc: Shankar K , + Chris Sutton , pgsql-performance@postgresql.org +In-Reply-To: +References: +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-3NVcCrkYRDt2aUdedp9D" +X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) +Date: 03 Apr 2003 15:04:19 -0700 +Message-Id: <1049407460.22236.93.camel@lyric.ofsloans.com> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-41.6 required=5.0 + tests=BAYES_20,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/43 +X-Sequence-Number: 1549 + +--=-3NVcCrkYRDt2aUdedp9D +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +Hey guys, + +On Thu, 2003-04-03 at 13:19, scott.marlowe wrote: +> On Thu, 3 Apr 2003, Shankar K wrote: +>=20 +> > Hi Scott, +> >=20 +> > Could you please share with us the problems you had +> > with linux 7.3 +> >=20 +> > would be really interested to know the kernel configs +> > and ext3 filesystem modes +>=20 +> Actually, I had a couple of problems with it, one of which was that I=20 +> couldn't get it to book with ext3 file systems properly. I think it was= +=20 +> something to do with ext3 on linux kernel RAID sets that wouldn't work=20 +> right. There's probably a fix for it, but 7.2 is pretty stable, and we= +=20 +> can wait for 8.0 or maybe look at another distro. +>=20 + +Normally I stay far far away from the distro wars / filesystem +discussions. However I'd like to offer information about the systems we +use here at OFS. The 2 core database servers are a matched pair of +system with the following statistics.=20=20 +Dual AMD MP 1800's +Tyan Thunder K7x motherboard +LSI Megaraid Elite 1650 controller w/ battery pack & 128 Mb cache +5 Seagate Cheetak 10k 36 Gig drives Configured in a raid 1+0 w/ hot +spare. + +Both are using the stock redhat 7.3 kernel w/ the latest LSI megaraid +drivers and firmware. + +The postgresql cluster itself contains the records and information +necessary to process loans and loan applications.=20 + +We are using rserv ( from contrib ) to replicate data from three +databases in the cluster between the two servers. ( Hahah, I think we +may be the only people using this in production or something. ) + +At any rate we use ext3 on the filesystems and we've had no problems at +all with the systems. Everything is stable and runs. We keep the +machines running and available 24/7 with scheduled downtime transitions +to the redundant servers as we need to for whatever kind of +enhancements. + +The largest table in the cluster btw, has 4.2 million tuples in it and +its the rserv log table. + +Hope this gives you some additional information to base your decisions +on. + +Sincerely, +Will LaShell + + + +--=-3NVcCrkYRDt2aUdedp9D +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.7 (GNU/Linux) + +iD8DBQA+jK/jZr3R5kgOZd0RArpaAJwM0jTCeAZnB19u+krDCJn90pWJ8QCcDCbl +GrHnL7zWSWCG3EKBhJyhQFg= +=AKmS +-----END PGP SIGNATURE----- + +--=-3NVcCrkYRDt2aUdedp9D-- + + +From pgsql-sql-owner@postgresql.org Thu Apr 3 17:14:18 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6172E475CE5 + for ; Thu, 3 Apr 2003 17:14:17 -0500 (EST) +Received: from lucifer.akyasociados.com.ar (unknown [200.69.203.237]) + by postgresql.org (Postfix) with ESMTP id 437F3475A8D + for ; Thu, 3 Apr 2003 17:14:16 -0500 (EST) +Received: from taz.oficina (taz.oficina [192.168.1.197]) (authenticated + bits=0) + by lucifer.akyasociados.com.ar (8.12.8/8.12.8) with ESMTP id + h33MJjkw090858; Thu, 3 Apr 2003 19:19:45 -0300 (ART) + (envelope-from franco@akyasociados.com.ar) +From: Franco Bruno Borghesi +Organization: AK y Asociados S.R.L. +To: Robert Treat , + pgsql-sql@postgresql.org +Subject: Re: can i make this sql query more efficiant? +Date: Thu, 3 Apr 2003 19:15:15 -0300 +User-Agent: KMail/1.5 +References: <1049403724.13799.5473.camel@camel> +In-Reply-To: <1049403724.13799.5473.camel@camel> +MIME-Version: 1.0 +Content-Type: multipart/signed; protocol="application/pgp-signature"; + micalg=pgp-sha1; boundary="Boundary-02=_0JLj+LbEzho6ijt"; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Message-Id: <200304031915.16517.franco@akyasociados.com.ar> +X-Spam-Status: No, hits=-38.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/54 +X-Sequence-Number: 12755 + +--Boundary-02=_0JLj+LbEzho6ijt +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable +Content-Description: signed data +Content-Disposition: inline + +if you're allowed to change the resultset structure, you could do: +SELECT + event, + level,=20 + count(*) +FROM + baz +GROUP BY + event, + level;=20=20=20 + + event | level | count +-------+-------+------- + x | 1 | 1 + x | 2 | 1 + x | 3 | 1 + y | 2 | 1 + y | 3 | 2 +(5 rows) + +of course it doesn't show you the rows where the count is zero. +if you need the zeros, do this + +SELECT=20=20=20 + EL.event, + EL.level,=20 + count(baz.*) +FROM + ( + SELECT DISTINCT + B1.event, B2.level=20 + FROM=20 + baz B1=20 + CROSS JOIN baz B2 + ) EL + LEFT JOIN baz ON (baz.event=3DEL.event AND baz.level=3DEL.level)=20=20 +GROUP BY + EL.event, + EL.level;=20=20=20 + + event | level | count +-------+-------+------- + x | 1 | 1 + x | 2 | 1 + x | 3 | 1 + y | 1 | 0 + y | 2 | 1 + y | 3 | 2 +(6 rows) + +hope it helps. + +On Thursday 03 April 2003 18:02, Robert Treat wrote: +> create table baz (event text, level int); +> +> insert into baz values ('x',1); +> insert into baz values ('x',2); +> insert into baz values ('x',3); +> insert into baz values ('y',2); +> insert into baz values ('y',3); +> insert into baz values ('y',3); +> +> select * from baz; +> +> event | level +> -------+------- +> x | 1 +> x | 2 +> x | 3 +> y | 2 +> y | 3 +> y | 3 +> (6 rows) +> +> +> I want to know how many ones, twos, and threes there are for each event: +> +> select +> event, +> (select count(*) from baz a +> where level =3D 1 and a.event=3Dbaz.event) as ones, +> (select count(*) from baz a +> where level =3D 2 and a.event=3Dbaz.event) as twos, +> (select count(*) from baz a +> where level =3D 3 and a.event=3Dbaz.event) as threes +> from +> baz +> group by +> event; +> +> which gives me: +> +> event | ones | twos | threes +> -------+------+------+-------- +> x | 1 | 1 | 1 +> y | 0 | 1 | 2 +> (2 rows) +> +> +> which is fine, but I am wondering if there is a better way to do this? +> I'd mainly like to reduce the number of subqueries involved. Another +> improvement would be to not have to explicitly query for each level, +> though this isn't as big since I know the range of levels in advance +> (famous last words for a dba :-) +> +> Thanks in advance, +> +> Robert Treat +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 3: if posting/reading through Usenet, please send an appropriate +> subscribe-nomail command to majordomo@postgresql.org so that your +> message can get through to the mailing list cleanly + +--Boundary-02=_0JLj+LbEzho6ijt +Content-Type: application/pgp-signature +Content-Description: signature + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (FreeBSD) + +iD8DBQA+jLJ0z/PwDAvtu7oRApe3AKCV0gNktohyYBn9I2eqQZ31RDlVQACcDWnx +iJFOEWxG3uY6RCHyLbB1rAo= +=6bXU +-----END PGP SIGNATURE----- + +--Boundary-02=_0JLj+LbEzho6ijt-- + + +From pgsql-general-owner@postgresql.org Mon Apr 7 12:21:53 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 2C9D1476036; Thu, 3 Apr 2003 17:07:55 -0500 (EST) +Received: from snoopy.mohawksoft.com (h0030f1382639.ne.client2.attbi.com + [24.60.194.163]) by postgresql.org (Postfix) with ESMTP + id 4ABDD475CE5; Thu, 3 Apr 2003 17:07:54 -0500 (EST) +Received: from mohawksoft.com (snoopy.mohawksoft.com [127.0.0.1]) + by snoopy.mohawksoft.com (8.11.6/8.11.6) with ESMTP id h33MJDZ23701; + Thu, 3 Apr 2003 17:19:13 -0500 +Message-ID: <3E8CB361.4010207@mohawksoft.com> +Date: Thu, 03 Apr 2003 17:19:13 -0500 +From: mlw +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; + rv:1.0.1) Gecko/20020823 Netscape/7.0 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Bruno Wolff III +Cc: josh@agliodbs.com, pgsql-general@postgresql.org, + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <20030403210147.GB30860@wolff.to> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-25.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,REFERENCES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/431 +X-Sequence-Number: 40496 + + + +Bruno Wolff III wrote: + +>On Thu, Apr 03, 2003 at 13:26:01 -0500, +> pgsql@mohawksoft.com wrote: +> +> +>>I don't know that it meets your criteria, but..... +>> +>>I have a set of scripts and a program that will load the US Census TigerUA +>>database into PostgreSQL. The thing is absolutely freak'n huge. I forget +>>which, but it is either 30g or 60g of data excluding indexes. +>> +>> +> +>Are the data model or the loading scripts available publicly? +>I have the tiger data and a program that uses it to convert addresses +>to latitude and longitude, but I don't really like the program and +>was thinking about trying to load the data into a database and do +>queries against the database to find location. +> +> +> +I have a set of scripts, SQL table defs, a small C program, along with a +set of field with files that loads it into PGSQL using the "copy from +stdin" It works fairly well, but takes a good long time to load it all. + +Should I put it in the download section of my website? + + +From pgsql-general-owner@postgresql.org Thu Apr 3 17:20:52 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0F124476323 + for ; + Thu, 3 Apr 2003 17:20:46 -0500 (EST) +Received: from wolff.to (wolff.to [66.93.249.74]) + by postgresql.org (Postfix) with SMTP id 2A2F6476036 + for ; + Thu, 3 Apr 2003 17:20:45 -0500 (EST) +Received: (qmail 32153 invoked by uid 500); 3 Apr 2003 22:20:37 -0000 +Date: Thu, 3 Apr 2003 16:20:37 -0600 +From: Bruno Wolff III +To: mlw +Cc: josh@agliodbs.com, pgsql-general@postgresql.org, + pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing +Message-ID: <20030403222037.GA32097@wolff.to> +Mail-Followup-To: mlw , josh@agliodbs.com, + pgsql-general@postgresql.org, pgsql-performance@postgresql.org, + pgsql-hackers@postgresql.org +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <20030403210147.GB30860@wolff.to> <3E8CB361.4010207@mohawksoft.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <3E8CB361.4010207@mohawksoft.com> +User-Agent: Mutt/1.5.4i +X-Spam-Status: No, hits=-34.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SUSPICIOUS_RECIPS, USER_AGENT_MUTT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/281 +X-Sequence-Number: 40346 + +On Thu, Apr 03, 2003 at 17:19:13 -0500, + mlw wrote: +> +> I have a set of scripts, SQL table defs, a small C program, along with a +> set of field with files that loads it into PGSQL using the "copy from +> stdin" It works fairly well, but takes a good long time to load it all. +> +> Should I put it in the download section of my website? + +Yes. I would be interested in looking at it even if I don't use exactly +the same way to do stuff. Taking a logn time to load the data into the +database isn't a big deal for me. reading through the tiger (and FIPS) data +documentation it seemed like there might be some gotchas in unusual cases +and I am not sure the google contest program really handled things right +so I would like to see another implementation. I am also interested in the +data model as that will save me some time. + + +From pgsql-sql-owner@postgresql.org Fri Apr 4 01:02:13 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2C32D474E44 + for ; Fri, 4 Apr 2003 01:02:12 -0500 (EST) +Received: from serwer.skawsoft.com.pl (serwer.skawsoft.com.pl [213.25.37.66]) + by postgresql.org (Postfix) with ESMTP id 8C78F474E42 + for ; Fri, 4 Apr 2003 01:02:10 -0500 (EST) +Received: from lamer.pl (localhost [127.0.0.1]) + by serwer.skawsoft.com.pl (Postfix) with ESMTP + id 2DEF16A283; Fri, 4 Apr 2003 08:02:09 +0200 (CEST) +From: "Tomasz Myrta" +To: Robert Treat , + pgsql-sql@postgresql.org +Subject: Re: can i make this sql query more efficiant? +Date: Fri, 4 Apr 2003 08:02:09 +0900 +Message-Id: <20030404080209.M3259@klaster.net> +In-Reply-To: <1049403724.13799.5473.camel@camel> +References: <1049403724.13799.5473.camel@camel> +X-Mailer: Open WebMail 1.62 20020221 +X-OriginatingIP: 217.96.97.171 (jasiek) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-2 +X-Spam-Status: No, hits=-16.2 required=5.0 + tests=BAYES_01,DATE_IN_PAST_06_12,IN_REP_TO,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/62 +X-Sequence-Number: 12763 + + +> select +> event, +> (select count(*) from baz a +> where level = 1 and a.event=baz.event) as ones, +> (select count(*) from baz a +> where level = 2 and a.event=baz.event) as twos, +> (select count(*) from baz a +> where level = 3 and a.event=baz.event) as threes +> from +> baz +> group by +> event; +> +> which gives me: +> +> event | ones | twos | threes +> -------+------+------+-------- +> x | 1 | 1 | 1 +> y | 0 | 1 | 2 +> (2 rows) + +What about this: +select + event, + sum(case when level=1 then 1 else 0 end) as ones, + sum(case when level=2 then 1 else 0 end) as twos, + sum(case when level=3 then 1 else 0 end) as threes +from baz +group by event; + +Regards, +Tomasz Myrta + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 18:12:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A1883476237 + for ; + Thu, 3 Apr 2003 18:12:49 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 4CFA7475F5F + for ; + Thu, 3 Apr 2003 18:12:48 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2941177; Thu, 03 Apr 2003 15:12:43 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Will LaShell , + "scott.marlowe" +Subject: Re: ext3 filesystem / linux 7.3 +Date: Thu, 3 Apr 2003 15:12:45 -0800 +User-Agent: KMail/1.4.3 +Cc: Shankar K , + Chris Sutton , pgsql-performance@postgresql.org +References: + <1049407460.22236.93.camel@lyric.ofsloans.com> +In-Reply-To: <1049407460.22236.93.camel@lyric.ofsloans.com> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304031512.45007.josh@agliodbs.com> +X-Spam-Status: No, hits=-28.9 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/46 +X-Sequence-Number: 1552 + +Will, + + +> At any rate we use ext3 on the filesystems and we've had no problems at +> all with the systems. Everything is stable and runs. We keep the +> machines running and available 24/7 with scheduled downtime transitions +> to the redundant servers as we need to for whatever kind of +> enhancements. + +Hey, can we use you as a case study for advocacy.openoffice.org? + +--=20 +-Josh Berkus + +______AGLIO DATABASE SOLUTIONS___________________________ + Josh Berkus + Complete information technology josh@agliodbs.com + and data management solutions (415) 565-7293 + for law firms, small businesses fax 621-2533 + and non-profit organizations. San Francisco + + +From pgsql-sql-owner@postgresql.org Thu Apr 3 18:13:24 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8612B474E44 + for ; Thu, 3 Apr 2003 18:13:23 -0500 (EST) +Received: from email01.aon.at (WARSL401PIP8.highway.telekom.at [195.3.96.97]) + by postgresql.org (Postfix) with SMTP id A0B1E474E42 + for ; Thu, 3 Apr 2003 18:13:22 -0500 (EST) +Received: (qmail 640924 invoked from network); 3 Apr 2003 23:13:24 -0000 +Received: from m169p008.dipool.highway.telekom.at (HELO cantor) ([62.46.11.8]) + (envelope-sender ) + by qmail1rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 3 Apr 2003 23:13:24 -0000 +From: Manfred Koizar +To: Robert Treat +Cc: pgsql-sql@postgresql.org +Subject: Re: can i make this sql query more efficiant? +Date: Fri, 04 Apr 2003 01:13:18 +0200 +Message-ID: <2afp8vsf99lhrrtr411ncivnr577s1v394@4ax.com> +References: <1049403724.13799.5473.camel@camel> +In-Reply-To: <1049403724.13799.5473.camel@camel> +X-Mailer: Forte Agent 1.8/32.548 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-31.4 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_FORTE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/56 +X-Sequence-Number: 12757 + +On 03 Apr 2003 16:02:04 -0500, Robert Treat + wrote: +>select +> event, +> (select count(*) from baz a +> where level = 1 and a.event=baz.event) as ones, +> (select count(*) from baz a +> where level = 2 and a.event=baz.event) as twos, +> (select count(*) from baz a +> where level = 3 and a.event=baz.event) as threes +>from +> baz +>group by +> event; + +>which is fine, but I am wondering if there is a better way to do this? +>I'd mainly like to reduce the number of subqueries involved. + +SELECT event, + SUM (CASE level WHEN 1 THEN 1 ELSE 0 END) AS ones, + SUM (CASE level WHEN 2 THEN 1 ELSE 0 END) AS twos, + SUM (CASE level WHEN 3 THEN 1 ELSE 0 END) AS threes + FROM baz + GROUP BY event; + +> Another +>improvement would be to not have to explicitly query for each level, + +This might be a case for a clever set returning function, but that's +not my realm. Wait for Joe to jump in ;-) + +Servus + Manfred + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 21:36:04 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7635A474E44 + for ; + Thu, 3 Apr 2003 21:36:03 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id BEE4B474E42 + for ; + Thu, 3 Apr 2003 21:36:01 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h342Pg919254; + Thu, 3 Apr 2003 21:25:42 -0500 +Message-ID: <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: , +Cc: +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> +Subject: Re: [HACKERS] OSS database needed for testing +Date: Thu, 3 Apr 2003 21:43:27 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-20.2 required=5.0 + tests=BAYES_10,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,RCVD_IN_NJABL, + REFERENCES,X_NJABL_OPEN_PROXY autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/47 +X-Sequence-Number: 1553 + +Hi Josh, + +Let me vote on the Tiger data. I used to use this database. It is public, +updated by the government, VERY useful in own right, it works well with the +earthdistance contribution, a real world database a lot of us use and I +think you can put together some killer scripts on it. + +Can I vote twice? + + Jeff + +----- Original Message ----- +From: +To: +Cc: ; ; + +Sent: Thursday, April 03, 2003 1:26 PM +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing + + +> I don't know that it meets your criteria, but..... +> +> I have a set of scripts and a program that will load the US Census TigerUA +> database into PostgreSQL. The thing is absolutely freak'n huge. I forget +> which, but it is either 30g or 60g of data excluding indexes. +> +> Also, if that is too much, I have a similar setup to load the FreeDB music +> database, from www.freedb.org. It has roughly 670,000 entries in +"cdtitles" +> and 8 million entries in "cdsongs." +> +> Either one of which, I would be willing to send you the actual DB on cd(s) +> if you pay for postage and media. +> +> +> > Folks, +> > +> > Please pardon the cross-posting. +> > +> > A small group of us on the Performance list were discussing the first +> > steps toward constructing a comprehensive Postgresql installation +> > benchmarking tool, mostly to compare different operating systems and +> > file systemsm but later to be used as a foundation for a tuning +> > wizard. +> > +> > To do this, we need one or more real (not randomly generated*) +> > medium-large database which is or can be BSD-licensed (data AND +> > schema). This database must have: +> > +> > 1) At least one "main" table with 12+ columns and 100,000+ rows (each). +> > 2) At least 10-12 additional tables of assorted sizes, at least half of +> > which should have Foriegn Key relationships to the main table(s) or +> > each other. 3) At least one large text or varchar field among the +> > various tables. +> > +> > In addition, the following items would be helpful, but are not +> > required: 4) Views, triggers, and functions built on the database +> > 5) A query log of database activity to give us sample queries to work +> > with. 6) Some complex data types, such as geometric, network, and/or +> > custom data types. +> > +> > Thanks for any leads you can give me! +> > +> > (* To forestall knee-jerk responses: Randomly generated data does not +> > look or perform the same as real data in my professional opinion, and +> > I'm the one writing the test scripts.) +> > +> > -- +> > -Josh Berkus +> > Aglio Database Solutions +> > San Francisco +> > +> > +> > ---------------------------(end of +> > broadcast)--------------------------- TIP 1: subscribe and unsubscribe +> > commands go to majordomo@postgresql.org +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the unregister command +> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 23:29:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id ADB0E475ED4 + for ; + Thu, 3 Apr 2003 23:29:20 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id EC850475E82 + for ; + Thu, 3 Apr 2003 23:29:19 -0500 (EST) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2941683; Thu, 03 Apr 2003 20:29:17 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Jeffrey D. Brower" , +Subject: Re: [HACKERS] OSS database needed for testing +Date: Thu, 3 Apr 2003 20:29:12 -0800 +User-Agent: KMail/1.4.3 +Cc: +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> +In-Reply-To: <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Message-Id: <200304032029.12450.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/48 +X-Sequence-Number: 1554 + +Jeff, + +> Let me vote on the Tiger data. I used to use this database. It is publi= +c, +> updated by the government, VERY useful in own right, it works well with t= +he +> earthdistance contribution, a real world database a lot of us use and I +> think you can put together some killer scripts on it. + +We'd have to use a subset of it. 30G is a little larger than anything we= +=20 +want people to download as a test package. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 3 23:54:22 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0246C475A45 + for ; + Thu, 3 Apr 2003 23:54:22 -0500 (EST) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 3FC0F475458 + for ; + Thu, 3 Apr 2003 23:54:21 -0500 (EST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h344s62L002995; + Thu, 3 Apr 2003 23:54:06 -0500 (EST) +To: Josh Berkus +Cc: "Jeffrey D. Brower" , pgsql@mohawksoft.com, + pgsql-performance@postgresql.org +Subject: Re: [HACKERS] OSS database needed for testing +In-reply-to: <200304032029.12450.josh@agliodbs.com> +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> + <200304032029.12450.josh@agliodbs.com> +Comments: In-reply-to Josh Berkus + message dated "Thu, 03 Apr 2003 20:29:12 -0800" +Date: Thu, 03 Apr 2003 23:54:06 -0500 +Message-ID: <2994.1049432046@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.1 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/49 +X-Sequence-Number: 1555 + +Josh Berkus writes: +> We'd have to use a subset of it. 30G is a little larger than anything we +> want people to download as a test package. + +Yeah, it seems a bit over the top ... + +The FCC database sounded like an interesting alternative to me. + + regards, tom lane + + +From pgsql-bugs-owner@postgresql.org Fri Apr 4 05:49:27 2003 +X-Original-To: pgsql-bugs@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id ECC59475458 + for ; Fri, 4 Apr 2003 05:49:25 -0500 (EST) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id B8B1F474E42 + for ; Fri, 4 Apr 2003 05:49:24 -0500 (EST) +Received: (qmail 8315 invoked from network); 4 Apr 2003 10:49:25 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 4 Apr 2003 10:49:25 -0000 +From: "Robert John Shepherd" +To: +Subject: Rapid deteriation of performance (might be caused by tsearch?) in + 7.3.2 +Date: Fri, 4 Apr 2003 11:49:25 +0100 +Message-ID: <000201c2fa97$dc2197f0$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-1.6 required=5.0 + tests=BAYES_30 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/25 +X-Sequence-Number: 5798 + +Up until a few days ago I have been running Postgresl 7.2.3 with Tsearch +from the contrib dir, but at various times the performance of the +database would suddenly and rapidly deteriate so that queries which +previously took 500ms then took 8 or 9 seconds. + +The only cure is a backup and restore of the database, vacuuming and +analysing does nothing. I even tried rebuilding all indexes once which +didn't seem to help. + +This was an annoying but intermittent thing, which happened the last +time this Wednesday. Since I was doing a backup and restore anyway, I +decided to upgrade to 7.3.2 in the hope this might fix the annoying +problem, however it has made it WAY worse. + +Rather than going a few weeks (and sometimes months) in between having +to use this fix, I am now having to do it almost every single day. I'm +now lucky if it lasts 24 hours before it brings my website to a total +crawl. + +There is nothing special about my database other than the fact that I +use the Tsearch addon. Now if I go and do a bit update to the Tsearch +indexes on a table, with for example: + + UPDATE tblmessages SET strmessageidx=txt2txtidx(strheading || ' +' || strmessage); + +Then that instantly brings the whole database to a crawl, which no +amount of index rebuilding, vacuuming and analysing helps. + +Help! (And sorry if this is the wrong list) + + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 06:01:19 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8667F475B47 + for ; + Fri, 4 Apr 2003 06:01:17 -0500 (EST) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 47F32475A45 + for ; + Fri, 4 Apr 2003 06:01:15 -0500 (EST) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h34B1Dg20186 + for ; Fri, 4 Apr 2003 16:31:13 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h34B1D720181 + for ; Fri, 4 Apr 2003 16:31:13 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: [OT][ANNOUNCEMENT]Announcing first public release of Open Application + Server +Date: Fri, 4 Apr 2003 16:31:49 +0530 +User-Agent: KMail/1.5 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304041631.49328.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-6.6 required=5.0 tests=BAYES_01,USER_AGENT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/50 +X-Sequence-Number: 1556 + +Hello all, + +I am very glad to announce first public release of Open Application Server. + +This is an application framework built in C++, to make use of existing APIs in +internet +application. + +It provides + +* A thread based request delivery architecture +* support of request handlers loaded from external libraries +* Support of additional application API such as http, SMTP etc. + +The features: + +* Written in C++ +* mutlithreaded application +* High performance and scalable +* Provides object-packing technology +* Native interface with apache to act as web application server + +The project is available from http://oasserver.sourceforge.net. The mailing +list is not active as yet +but it should be up in short time(by tomorrow hopefully). + +A complete web application built with OAS+postgresql+apache is also available +from CVS. This is a issue +tracking and resource booking system. + +There are no packages/tarballs available right now. Please use anonymous cvs. +I plan to relase packages +in short time. + +The CVS modules are oasserver and phd respectively. + +This is done so that I can update install documentation to cater for variety +of build platforms. Right now, +I can test the build only on slackware/mandrake/freeBSD. + +Shridhar + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 06:28:56 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AAEBC475B47 + for ; + Fri, 4 Apr 2003 06:28:54 -0500 (EST) +Received: from smtp.inode.at (smtp-05.inode.at [62.99.194.7]) + by postgresql.org (Postfix) with ESMTP id BBDD3474E42 + for ; + Fri, 4 Apr 2003 06:28:49 -0500 (EST) +Received: from line-f-148.adsl-dynamic.inode.at ([62.99.193.148]:54276 + helo=andi-lap) by smtp.inode.at with smtp (Exim 4.10) + id 191PME-0001Ug-00; Fri, 04 Apr 2003 13:27:42 +0200 +Received: by andi-lap (sSMTP sendmail emulation); + Fri, 4 Apr 2003 13:28:50 +0200 +Subject: Re: ext3 filesystem / linux 7.3 +From: Andreas Kostyrka +To: Andrew Sullivan +Cc: pgsql-performance@postgresql.org +In-Reply-To: <20030402155649.GC15624@libertyrms.info> +References: <20030331205544.19785.qmail@web21104.mail.yahoo.com> + <08f801c2f874$c6aac3d0$0b02a8c0@pointhere.net> + <20030401175519.GA9553@mail> <1049296706.20242.331.camel@andi-lap> + <20030402155649.GC15624@libertyrms.info> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-MqqAAqY4FbPK4UXZ4Hjx" +Organization: +Message-Id: <1049455729.17931.82.camel@andi-lap> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 +Date: 04 Apr 2003 13:28:50 +0200 +X-Spam-Status: No, hits=-45.1 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/51 +X-Sequence-Number: 1557 + +--=-MqqAAqY4FbPK4UXZ4Hjx +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Wed, 2003-04-02 at 17:56, Andrew Sullivan wrote: +> On Wed, Apr 02, 2003 at 05:18:26PM +0200, Andreas Kostyrka wrote: +>=20 +> > Well, I've been using ReiserFS now for years, and never had any problems +> > with it.=20 +>=20 +> Me too. But the "known failure modes" that people keep reporting +> about have to do with completely trashing, say, a whole page of data.=20 +> Your directories are fine, but the data is all hosed. +>=20 +> I've never had it happen. I've never seen anyone who can +> consistently reproduce it. But I've certainly read about it often +> enough to have pretty serious reservations about relying on the +> filesystem for data I can't afford to lose. +Well, than backups and statistics are your only solution. +Only way to know if something works is to test it for some time. (You +never know if something in your use doesn't trigger some border case of +malfunction in the kernel.) + +Andreas +--=20 +Andreas Kostyrka +Josef-Mayer-Strasse 5 +83043 Bad Aibling + +--=-MqqAAqY4FbPK4UXZ4Hjx +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (GNU/Linux) + +iD8DBQA+jWxxHJdudm4KnO0RAoMIAKDh03FEBclLrTj/umBmHWJUvjFypwCgtxFF ++f4h264OkvFJU56ZVY4eqJk= +=Swu8 +-----END PGP SIGNATURE----- + +--=-MqqAAqY4FbPK4UXZ4Hjx-- + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 07:11:06 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 41861474E42 + for ; + Fri, 4 Apr 2003 07:11:04 -0500 (EST) +Received: from snoopy.mohawksoft.com (h0030f1382639.ne.client2.attbi.com + [24.60.194.163]) + by postgresql.org (Postfix) with ESMTP id EA3D7474E42 + for ; + Fri, 4 Apr 2003 07:10:32 -0500 (EST) +Received: from mohawksoft.com (snoopy.mohawksoft.com [127.0.0.1]) + by snoopy.mohawksoft.com (8.11.6/8.11.6) with ESMTP id h34CLoZ30121; + Fri, 4 Apr 2003 07:21:54 -0500 +Message-ID: <3E8D78DD.1060202@mohawksoft.com> +Date: Fri, 04 Apr 2003 07:21:49 -0500 +From: mlw +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; + rv:1.0.1) Gecko/20020823 Netscape/7.0 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Josh Berkus +Cc: "Jeffrey D. Brower" , pgsql-performance@postgresql.org +Subject: Re: [HACKERS] OSS database needed for testing +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> + <200304032029.12450.josh@agliodbs.com> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-25.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,REFERENCES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/52 +X-Sequence-Number: 1558 + + + +Josh Berkus wrote: + +>Jeff, +> +> +> +>>Let me vote on the Tiger data. I used to use this database. It is public, +>>updated by the government, VERY useful in own right, it works well with the +>>earthdistance contribution, a real world database a lot of us use and I +>>think you can put together some killer scripts on it. +>> +>> +> +>We'd have to use a subset of it. 30G is a little larger than anything we +>want people to download as a test package. +> +> +> +Actually, come to think of it, the TigerUA DB is in chunks. You can use +as much or as little as you want. I'll put the loader scripts on my +download page tonight. + +Here is the home page for the data: +http://www.census.gov/geo/www/tiger/tigerua/ua_tgr2k.html + + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 07:38:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 815C7475F53 + for ; + Fri, 4 Apr 2003 07:38:03 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id 67AE9475F16 + for ; + Fri, 4 Apr 2003 07:38:02 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h34CRi928804; + Fri, 4 Apr 2003 07:27:44 -0500 +Message-ID: <0c2201c2faa8$136c9c90$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: "Josh Berkus" , +Cc: +References: <200304030955.16543.josh@agliodbs.com> + <2598.141.154.39.187.1049394361.squirrel@mail.mohawksoft.com> + <0c0f01c2fa53$f8eb8790$0b02a8c0@pointhere.net> + <200304032029.12450.josh@agliodbs.com> +Subject: Re: [HACKERS] OSS database needed for testing +Date: Fri, 4 Apr 2003 07:45:29 -0500 +Organization: Green Visor, Inc. +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-17.5 required=5.0 + tests=BAYES_20,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,RCVD_IN_NJABL, + REFERENCES,X_NJABL_OPEN_PROXY autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/53 +X-Sequence-Number: 1559 + +Absolutely. We could just use one large state or several small ones and let +folks download the whole thing if they wanted. Using that technique you +could control the size of the test quite closely and still make something +potentially quite valuable as a contribution beyond the bench. + +----- Original Message ----- +From: "Josh Berkus" +To: "Jeffrey D. Brower" ; +Cc: +Sent: Thursday, April 03, 2003 11:29 PM +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing + + +> Jeff, +> +> > Let me vote on the Tiger data. I used to use this database. It is +public, +> > updated by the government, VERY useful in own right, it works well with +the +> > earthdistance contribution, a real world database a lot of us use and I +> > think you can put together some killer scripts on it. +> +> We'd have to use a subset of it. 30G is a little larger than anything we +> want people to download as a test package. +> +> -- +> Josh Berkus +> Aglio Database Solutions +> San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 09:50:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A289C4762A2 + for ; + Fri, 4 Apr 2003 09:50:41 -0500 (EST) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 953F8476237 + for ; + Fri, 4 Apr 2003 09:50:37 -0500 (EST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id A32E1D62D; Fri, 4 Apr 2003 06:50:41 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 98B3A5C0A; Fri, 4 Apr 2003 06:50:41 -0800 (PST) +Date: Fri, 4 Apr 2003 06:50:41 -0800 (PST) +From: Stephan Szabo +To: Robert John Shepherd +Cc: +Subject: Re: [BUGS] Rapid deteriation of performance (might be caused by +In-Reply-To: <000201c2fa97$dc2197f0$f3b0313e@LAIKA> +Message-ID: <20030404064515.Q92769-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,HTML_TAG_BALANCE_TABLE, + IN_REP_TO,QUOTED_EMAIL_TEXT,REPLY_WITH_QUOTES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/54 +X-Sequence-Number: 1560 + + +On Fri, 4 Apr 2003, Robert John Shepherd wrote: + +> Up until a few days ago I have been running Postgresl 7.2.3 with Tsearch +> from the contrib dir, but at various times the performance of the +> database would suddenly and rapidly deteriate so that queries which +> previously took 500ms then took 8 or 9 seconds. + +Hmm, what are the before and after explain analyze results? Also, what +are your conf settings for shared buffers, sort memory and the fsm +parameters? + +> The only cure is a backup and restore of the database, vacuuming and +> analysing does nothing. I even tried rebuilding all indexes once which +> didn't seem to help. + +Did you do a regular vacuum or vacuum full? If only the former, it's +possible that you need to either vacuum more frequently and/or raise the +free space map settings in your configuration file. + +What does vacuum full verbose ; give you for the tables involved? + +> Help! (And sorry if this is the wrong list) +pgsql-performance is a better list, so I've replied to there. You'll +probably need to join in order to reply to list. + + +From pgsql-bugs-owner@postgresql.org Fri Apr 4 09:53:26 2003 +X-Original-To: pgsql-bugs@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 80D7247637E + for ; Fri, 4 Apr 2003 09:53:25 -0500 (EST) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id B910947637A + for ; Fri, 4 Apr 2003 09:53:24 -0500 (EST) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h34ErS2L005590; + Fri, 4 Apr 2003 09:53:28 -0500 (EST) +To: "Robert John Shepherd" +Cc: pgsql-bugs@postgresql.org +Subject: Re: Rapid deteriation of performance (might be caused by tsearch?) in + 7.3.2 +In-reply-to: <000201c2fa97$dc2197f0$f3b0313e@LAIKA> +References: <000201c2fa97$dc2197f0$f3b0313e@LAIKA> +Comments: In-reply-to "Robert John Shepherd" + message dated "Fri, 04 Apr 2003 11:49:25 +0100" +Date: Fri, 04 Apr 2003 09:53:28 -0500 +Message-ID: <5589.1049468008@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.1 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/27 +X-Sequence-Number: 5800 + +"Robert John Shepherd" writes: +> Help! (And sorry if this is the wrong list) + +Yes, it's the wrong list. pgsql-performance would be the place to +discuss this. We can't help you anyway without more details: show us +the EXPLAIN ANALYZE results for some of the slow queries. (Ideally +I'd like to see EXPLAIN ANALYZE for the same queries in both fast +and slow states ...) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 10:19:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D2D6A47633A + for ; + Fri, 4 Apr 2003 10:19:42 -0500 (EST) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id A0819476334 + for ; + Fri, 4 Apr 2003 10:19:41 -0500 (EST) +Received: (qmail 11466 invoked from network); 4 Apr 2003 15:19:39 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 4 Apr 2003 15:19:39 -0000 +From: "Robert John Shepherd" +To: +Subject: Re: [BUGS] Rapid deteriation of performance (might be caused by + tsearch?) in 7.3.2 +Date: Fri, 4 Apr 2003 16:19:34 +0100 +Message-ID: <001e01c2fabd$9edfb860$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <20030404064515.Q92769-100000@megazone23.bigpanda.com> +Importance: Normal +X-Spam-Status: No, hits=-10.1 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT,QUOTE_TWICE_1 + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/55 +X-Sequence-Number: 1561 + +> > Up until a few days ago I have been running Postgresl 7.2.3 with +Tsearch +> > from the contrib dir, but at various times the performance of the +> > database would suddenly and rapidly deteriate so that queries which +> > previously took 500ms then took 8 or 9 seconds. + +> Hmm, what are the before and after explain analyze results? Also, +what +> are your conf settings for shared buffers, sort memory and the fsm +> parameters? + +shared_buffers = 40960 +sort_mem = 20480 +#max_fsm_relations = 1000 +#max_fsm_pages = 10000 + +As you can see I've not uncommented or touched the fsm parameters, I +have no idea what they do. Optimisation wise I have only played with +shared_buffers, sort_mem and max_connections. + + +> > The only cure is a backup and restore of the database + +> Did you do a regular vacuum or vacuum full? If only the former, it's +> possible that you need to either vacuum more frequently and/or raise +the +> free space map settings in your configuration file. + +I've been running this daily: + + vacuumdb -h localhost -a -z + +Should I be using the full switch then? + +I'll get back to you on the other questions if you think they are still +needed. + + +> pgsql-performance is a better list, so I've replied to there. You'll +> probably need to join in order to reply to list. + +Thanks, especially for not shouting at me heh, this is stressful enough +as it is. + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 10:29:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C882E476237 + for ; + Fri, 4 Apr 2003 10:29:43 -0500 (EST) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id AB454476036 + for ; + Fri, 4 Apr 2003 10:29:39 -0500 (EST) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 0939ED62D; Fri, 4 Apr 2003 07:29:44 -0800 (PST) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id F2DFB5C0A; Fri, 4 Apr 2003 07:29:43 -0800 (PST) +Date: Fri, 4 Apr 2003 07:29:43 -0800 (PST) +From: Stephan Szabo +To: Robert John Shepherd +Cc: +Subject: Re: [BUGS] Rapid deteriation of performance (might be +In-Reply-To: <001e01c2fabd$9edfb860$f3b0313e@LAIKA> +Message-ID: <20030404072355.Q93368-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/56 +X-Sequence-Number: 1562 + + +On Fri, 4 Apr 2003, Robert John Shepherd wrote: + +> > > Up until a few days ago I have been running Postgresl 7.2.3 with +> Tsearch +> > > from the contrib dir, but at various times the performance of the +> > > database would suddenly and rapidly deteriate so that queries which +> > > previously took 500ms then took 8 or 9 seconds. +> +> > Hmm, what are the before and after explain analyze results? Also, +> what +> > are your conf settings for shared buffers, sort memory and the fsm +> > parameters? +> +> shared_buffers = 40960 +> sort_mem = 20480 +> #max_fsm_relations = 1000 +> #max_fsm_pages = 10000 +> +> As you can see I've not uncommented or touched the fsm parameters, I +> have no idea what they do. Optimisation wise I have only played with +> shared_buffers, sort_mem and max_connections. +> +> +> > > The only cure is a backup and restore of the database +> +> > Did you do a regular vacuum or vacuum full? If only the former, it's +> > possible that you need to either vacuum more frequently and/or raise +> the +> > free space map settings in your configuration file. +> +> I've been running this daily: +> +> vacuumdb -h localhost -a -z +> +> Should I be using the full switch then? + +Well, you generally shouldn't need to if the fsm settings are high enough. +If you're doing really big updates like update each row of a 1 billion +row table, you may end up having to do one immediately following that. +Of course, if you're doing that, performance is probably not your biggest +concern. ;) + +Explain analyze'll tell us if the system is changing plans (presumably to +a worse one) - for example, deciding to move to a sequence scan because it +thinks that the index scan is now to expensive, or conversely moving to an +index scan because it thinks that there'll be too many reads, while those +page reads actually are fairly localized. The vacuum full verbose should +get some idea of how much empty space is there. + +> > pgsql-performance is a better list, so I've replied to there. You'll +> > probably need to join in order to reply to list. +> +> Thanks, especially for not shouting at me heh, this is stressful enough +> as it is. + +:) + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 11:09:36 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 3ADAD475A45; Fri, 4 Apr 2003 11:09:35 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id 439C6474E42; Fri, 4 Apr 2003 11:09:34 -0500 (EST) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942335; Fri, 04 Apr 2003 08:09:31 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Jeffrey D. Brower" , +Subject: Re: [PERFORM] OSS database needed for testing +Date: Fri, 4 Apr 2003 08:09:22 -0800 +User-Agent: KMail/1.4.3 +Cc: , pgsql-hackers@postgresql.org +References: <200304030955.16543.josh@agliodbs.com> + <200304032029.12450.josh@agliodbs.com> + <0c2201c2faa8$136c9c90$0b02a8c0@pointhere.net> +In-Reply-To: <0c2201c2faa8$136c9c90$0b02a8c0@pointhere.net> +MIME-Version: 1.0 +Message-Id: <200304040809.22065.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-28.9 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/148 +X-Sequence-Number: 37638 + +Jeff, Mlw,=20 + +> Absolutely. We could just use one large state or several small ones and +> let folks download the whole thing if they wanted. Using that technique +> you could control the size of the test quite closely and still make +> something potentially quite valuable as a contribution beyond the bench. + +Hold on a second. The FCC database is still a better choice because it is= +=20 +more complex with a carefully defined schema. The Tiger database would be= +=20 +good for doing tests of type 1 and 3, but not for tests of types 2 and 4. + +It would certainly be interesting to use the Tiger database as the basis fo= +r=20 +an additional type of test: + +6) Very Large Data Set: querying, then updating, 300+ selected rows from a= +=20 +2,000,000 + row table. + +... but I still see the FCC database as our best candidate for the battery = +of=20 +tests 1-5. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-sql-owner@postgresql.org Fri Apr 4 11:16:22 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 369AC47631F + for ; Fri, 4 Apr 2003 11:16:20 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 7A3B147631B + for ; Fri, 4 Apr 2003 11:16:19 -0500 (EST) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942345; Fri, 04 Apr 2003 08:16:16 -0800 +Content-Type: text/plain; + charset="iso-8859-2" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Tomasz Myrta" , + Robert Treat , pgsql-sql@postgresql.org +Subject: Re: can i make this sql query more efficiant? +Date: Fri, 4 Apr 2003 08:16:01 -0800 +User-Agent: KMail/1.4.3 +References: <1049403724.13799.5473.camel@camel> + <20030404080209.M3259@klaster.net> +In-Reply-To: <20030404080209.M3259@klaster.net> +MIME-Version: 1.0 +Message-Id: <200304040816.01369.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-22.7 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/67 +X-Sequence-Number: 12768 + +Tomasz, + +> What about this: +> select +> event, +> sum(case when level=3D1 then 1 else 0 end) as ones, +> sum(case when level=3D2 then 1 else 0 end) as twos, +> sum(case when level=3D3 then 1 else 0 end) as threes +> from baz +> group by event; + +That version is only more efficient for small data sets. I've generally= +=20 +found that case statements are slower than subselects for large data sets.= +=20 +YMMV. + +BTW, while it won't be faster, Joe Conway's crosstab function in /tablefunc= +=20 +does this kind of transformation. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 11:35:08 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4C0B84762A2 + for ; + Fri, 4 Apr 2003 11:35:07 -0500 (EST) +Received: from localhost.localdomain (208-41-234-242.client.dsl.net + [208.41.234.242]) + by postgresql.org (Postfix) with ESMTP id AFDC5476036 + for ; + Fri, 4 Apr 2003 11:35:05 -0500 (EST) +Received: from endeavour (endeavour.pointhere.net [192.168.2.11]) + by localhost.localdomain (8.11.6/8.11.6) with SMTP id h34GOm932538; + Fri, 4 Apr 2003 11:24:48 -0500 +Message-ID: <0c8101c2fac9$316ad290$0b02a8c0@pointhere.net> +Reply-To: "Jeffrey D. Brower" +From: "Jeffrey D. Brower" +To: , "Josh Berkus" +Cc: +References: <200304030955.16543.josh@agliodbs.com> + <200304032029.12450.josh@agliodbs.com> + <0c2201c2faa8$136c9c90$0b02a8c0@pointhere.net> + <200304040809.22065.josh@agliodbs.com> +Subject: Re: OSS database needed for testing +Date: Fri, 4 Apr 2003 11:42:33 -0500 +Organization: A Basic Marketing Company +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2600.0000 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +X-Spam-Status: No, hits=-17.5 required=5.0 + tests=BAYES_20,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,RCVD_IN_NJABL, + REFERENCES,X_NJABL_OPEN_PROXY autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/58 +X-Sequence-Number: 1564 + +I think you got me there. I have to agree with both points. + +(Besides, you are the one coding this thing and I think you understand it +better than I do.) + +Let me know if I can help. + + Jeff + +----- Original Message ----- +From: "Josh Berkus" +To: "Jeffrey D. Brower" ; +Cc: ; +Sent: Friday, April 04, 2003 11:09 AM +Subject: Re: [PERFORM] [HACKERS] OSS database needed for testing + + +> Jeff, Mlw, +> +> > Absolutely. We could just use one large state or several small ones and +> > let folks download the whole thing if they wanted. Using that technique +> > you could control the size of the test quite closely and still make +> > something potentially quite valuable as a contribution beyond the bench. +> +> Hold on a second. The FCC database is still a better choice because it is +> more complex with a carefully defined schema. The Tiger database would +be +> good for doing tests of type 1 and 3, but not for tests of types 2 and 4. +> +> It would certainly be interesting to use the Tiger database as the basis +for +> an additional type of test: +> +> 6) Very Large Data Set: querying, then updating, 300+ selected rows from a +> 2,000,000 + row table. +> +> ... but I still see the FCC database as our best candidate for the battery +of +> tests 1-5. +> +> -- +> Josh Berkus +> Aglio Database Solutions +> San Francisco +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 11:45:09 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A26BB474E42 + for ; + Fri, 4 Apr 2003 11:45:07 -0500 (EST) +Received: from cuthbert.rcsinc.local (unknown [205.217.85.84]) + by postgresql.org (Postfix) with ESMTP id 7ED964758E6 + for ; + Fri, 4 Apr 2003 11:44:36 -0500 (EST) +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable +Subject: Re: [PERFORM] OSS database needed for testing +X-MimeOLE: Produced By Microsoft Exchange V6.0.6375.0 +Date: Fri, 4 Apr 2003 11:47:56 -0500 +Message-ID: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] [HACKERS] OSS database needed for testing +Thread-Index: AcL6xZe0O5NuxSpzRnKHnOiFQ3MiwgAAoIgg +From: "Merlin Moncure" +To: "Josh Berkus" +Cc: +X-Spam-Status: No, hits=-6.6 required=5.0 + tests=BAYES_01 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/152 +X-Sequence-Number: 37642 + +The fcc FTP site is ftp.fcc.gov + +The location of the data of interest is at +/pub/Bureaus/Wireless/Databases/uls/. + +There are zip files (pipe delimited) in complete and the daily changed +files in daily. Theres lots of info in documentation which includes +excel spreadsheets of the schema. These will have to be converted to +sql statemtents. + +The ULS is the database system that holds the data for Fixed and Mobile +wireless services. This includes most two way systems and point to +multipoint (microwave) but not broadcast (AM, FM, TV) and not advanced +radio. + +The database is really a database of applications. It contains +application data submitted by wireless applicants.=20=20 + +There are two families of tables, prefixed with 'a' and 'l'. The 'a' +tables stand for application records that are pending being granted by +the fcc. The 'l' tables have received licenses and may or may not be +operating. + +Combined, the 'a' and 'l' zipfiles represent a specific service. For +example, 'a_micro' and 'l_micro' contain the applications and licensed +data for microwave systems. The different services have slightly +different layouts because they have different requirements. + +I strongly suggest looking at LMcomm and LMpriv first. These are the +fixed land mobile systems, and 90% of the entire database. They also +have identical layouts. + +There are a great deal of files in each zipfile, but here are the most +interesting: + +hd: header data +ad: application detail +an: antenna data +lo: location data +fr: frequency data +em: emission data + +There are others. I can help you write meaningful queries that are +quite complex and will require optimization techniques. + +Merlin + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 12:37:46 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 3493B4763A4; Fri, 4 Apr 2003 12:37:44 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id 4D00A476381; Fri, 4 Apr 2003 12:37:39 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942483; Fri, 04 Apr 2003 09:37:31 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Merlin Moncure" +Subject: Re: [PERFORM] OSS database needed for testing +Date: Fri, 4 Apr 2003 09:37:34 -0800 +User-Agent: KMail/1.4.3 +Cc: , pgsql-performance@postgresql.org +References: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> +In-Reply-To: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304040937.34362.josh@agliodbs.com> +X-Spam-Status: No, hits=-21.9 required=5.0 + tests=BAYES_10,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/160 +X-Sequence-Number: 37650 + +Merlin, + +> The fcc FTP site is ftp.fcc.gov +>=20 +> The location of the data of interest is at +> /pub/Bureaus/Wireless/Databases/uls/. + +Cool. I'll tackle this in a week or two. Right now, I'm being paid to=20 +convert a client's data and that'll keep me busy through the weekend ... + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 12:57:07 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id CF95E4758E6; Fri, 4 Apr 2003 12:57:05 -0500 (EST) +Received: from cuthbert.rcsinc.local (unknown [205.217.85.84]) + by postgresql.org (Postfix) with ESMTP + id 23263474E42; Fri, 4 Apr 2003 12:57:05 -0500 (EST) +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: quoted-printable +Subject: Re: [PERFORM] OSS database needed for testing +X-MimeOLE: Produced By Microsoft Exchange V6.0.6375.0 +Date: Fri, 4 Apr 2003 13:00:26 -0500 +Message-ID: <303E00EBDD07B943924382E153890E5434A93C@cuthbert.rcsinc.local> +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [PERFORM] [HACKERS] OSS database needed for testing +Thread-Index: AcL60VjZUYt9eVUZS3KRTUnNYPq3/QAAItEQ +From: "Merlin Moncure" +To: +Cc: , + +X-Spam-Status: No, hits=-15.5 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/161 +X-Sequence-Number: 37651 + +Josh Berkus wrote: +> Cool. I'll tackle this in a week or two. Right now, I'm being paid +to +> convert a client's data and that'll keep me busy through the weekend +... + +I would suggest downloading the data now. I can help get you started +with the create table statements and the import scripts. There are not +very many ways to get the data in a reasonable timeframe: the spi +functions or the copy command are a good place to start. Do not bother +with running stuff through insert queries: take my word for it, it just +won't work. Of course, if you use copy, you have to pre-format. Be +aware that you will have many gigabytes (like more than 20) of data +before you are done. + +Whatever you decide to do, document the process: the difficulty of +getting large amounts of data into postgres quickly and easily has been +a historical complaint of mine. Using mysql, it was a snap to get the +data in but using *that* database I really felt it couldn't handle this +much data. +=20=20 +I can also get you started with some example queries that should be +quite a challenge to set up to run quickly. After that, it's your +ballgame. + +Merlin + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 13:08:00 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 92E684758E6 + for ; + Fri, 4 Apr 2003 13:07:59 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id D08D5474E42 + for ; + Fri, 4 Apr 2003 13:07:58 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942527; Fri, 04 Apr 2003 10:07:50 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Merlin Moncure" +Subject: Re: OSS database needed for testing +Date: Fri, 4 Apr 2003 10:07:49 -0800 +User-Agent: KMail/1.4.3 +Cc: +References: <303E00EBDD07B943924382E153890E5434A93C@cuthbert.rcsinc.local> +In-Reply-To: <303E00EBDD07B943924382E153890E5434A93C@cuthbert.rcsinc.local> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304041007.49417.josh@agliodbs.com> +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/61 +X-Sequence-Number: 1567 + +Merlin,=20 + +> I would suggest downloading the data now. I can help get you started + +OK, downloading now. + +> with the create table statements and the import scripts. There are not +> very many ways to get the data in a reasonable timeframe: the spi +> functions or the copy command are a good place to start. Do not bother +> with running stuff through insert queries: take my word for it, it just +> won't work. Of course, if you use copy, you have to pre-format. Be +> aware that you will have many gigabytes (like more than 20) of data +> before you are done. + + From my perspective, the easiest and fastest way to do this is to create th= +e=20 +table definitions in PostgreSQL, and then to use Perl to convert the data= +=20 +format to something COPY will recognize. If you can do the create table= +=20 +statements for the LM* data, I can do the Perl scripts. + +Given that the *total* data is 20G, we'll want to use a subset of it. Per= +=20 +your suggestion, I am downloading the *LM* tables. I may truncate them=20 +further if the resulting database is too large. If some of the other table= +s=20 +are reference lists or child tables, please tell me and I will download the= +m=20 +as well. + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 14:03:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 629E3475F53 + for ; + Fri, 4 Apr 2003 14:03:14 -0500 (EST) +Received: from email02.aon.at (WARSL401PIP7.highway.telekom.at [195.3.96.94]) + by postgresql.org (Postfix) with SMTP id 443BF475C3D + for ; + Fri, 4 Apr 2003 14:03:13 -0500 (EST) +Received: (qmail 384036 invoked from network); 4 Apr 2003 19:03:11 -0000 +Received: from m154p001.dipool.highway.telekom.at (HELO cantor) ([62.46.9.33]) + (envelope-sender ) + by qmail2rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 4 Apr 2003 19:03:11 -0000 +From: Manfred Koizar +To: Josh Berkus +Cc: "Tomasz Myrta" , + Robert Treat , + pgsql-sql@postgresql.org, pgsql-performance@postgresql.org +Subject: Re: [SQL] can i make this sql query more efficiant? +Date: Fri, 04 Apr 2003 21:03:08 +0200 +Message-ID: +References: <1049403724.13799.5473.camel@camel> + <20030404080209.M3259@klaster.net> + <200304040816.01369.josh@agliodbs.com> +In-Reply-To: <200304040816.01369.josh@agliodbs.com> +X-Mailer: Forte Agent 1.8/32.548 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-27.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,RCVD_IN_DSBL, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_FORTE version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/62 +X-Sequence-Number: 1568 + +On Fri, 4 Apr 2003 08:16:01 -0800, Josh Berkus +wrote: +>That version is only more efficient for small data sets. I've generally +>found that case statements are slower than subselects for large data sets. + +I'd be honestly interested in the circumstances where you made that +observation. + +>YMMV. + +Yes, it does :-) Out of curiosity I did a few tests with PG 7.2 on my +old notebook: + +CREATE TABLE baz (event int, level int); +INSERT INTO baz SELECT (100*random()+0.5), (3*random()+0.5); +INSERT INTO baz SELECT (100*random()+0.5), (3*random()+0.5) FROM baz; +... +INSERT INTO baz SELECT (100*random()+0.5), (3*random()+0.5) FROM baz; +CREATE INDEX baz_event ON baz(event); +ANALYSE baz; + +SELECT event, + SUM (CASE level WHEN 1 THEN 1 ELSE 0 END) AS ones, + SUM (CASE level WHEN 2 THEN 1 ELSE 0 END) AS twos, + SUM (CASE level WHEN 3 THEN 1 ELSE 0 END) AS threes + FROM baz GROUP BY event; + +SELECT event, + (SELECT count(*) FROM baz a + WHERE level = 1 AND a.event=baz.event) AS ones, + (SELECT count(*) FROM baz a + WHERE level = 2 and a.event=baz.event) AS twos, + (SELECT count(*) FROM baz a + WHERE level = 3 and a.event=baz.event) AS threes + FROM baz GROUP BY event; + +tuples case subselect + 8K 718.48 msec 16199.88 msec + 32K 6168.18 msec 74742.85 msec +128K 25072.34 msec 304585.61 msec + +CLUSTER baz_event ON baz; ANALYSE baz; +This changes the subselect plan from seq scan to index scan. + +128K 12116.07 msec 17530.85 msec + +Add 128K more tuples, so that only the first half of the relation is +clustered. + +256K 45663.35 msec 117748.23 msec + +CLUSTER baz_event ON baz; ANALYSE baz; + +256K 23691.81 msec 35138.26 msec + +Maybe it is just the data distribution (100 events, 3 levels, +thousands of tuples) that makes CASE look faster than subselects ... + +Servus + Manfred + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 14:08:47 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id F219A475F53 + for ; + Fri, 4 Apr 2003 14:08:45 -0500 (EST) +Received: from utility.wgcr.org (unknown [206.74.232.205]) + by postgresql.org (Postfix) with ESMTP id 429DD475D3B + for ; + Fri, 4 Apr 2003 14:08:45 -0500 (EST) +Received: from utility.wgcr.org ([10.1.0.2]) + by utility.wgcr.org (8.12.8/8.12.5) with ESMTP id h34J8YFJ013368; + Fri, 4 Apr 2003 14:08:34 -0500 +Received: from ([10.1.2.233]) + by utility.wgcr.org (MailMonitor for SMTP v1.2.2 ) ; + Fri, 4 Apr 2003 14:08:34 -0500 (EST) +From: Lamar Owen +To: "Merlin Moncure" , + "Josh Berkus" +Subject: Re: [PERFORM] OSS database needed for testing +Date: Fri, 4 Apr 2003 14:08:31 -0500 +User-Agent: KMail/1.5 +Cc: +References: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> +In-Reply-To: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304041408.31175.lamar.owen@wgcr.org> +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/166 +X-Sequence-Number: 37656 + +On Friday 04 April 2003 11:47, Merlin Moncure wrote: +> The location of the data of interest is at +> /pub/Bureaus/Wireless/Databases/uls/. + +> wireless services. This includes most two way systems and point to +> multipoint (microwave) but not broadcast (AM, FM, TV) and not advanced +> radio. + +Also check out the cdbs files (which contain the broadcast stuff as well as +more) at /pub/Bureaus/Mass_Media/Databases/cdbs/ (which I would be more +interested in doing, since I am a broadcast engineer by profession....) +-- +Lamar Owen +WGCR Internet Radio +1 Peter 4:11 + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 14:26:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 2EB1B4758E6; Fri, 4 Apr 2003 14:26:20 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id 6BBB2474E42; Fri, 4 Apr 2003 14:26:19 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942665; Fri, 04 Apr 2003 11:26:11 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Manfred Koizar +Subject: Re: [SQL] can i make this sql query more efficiant? +Date: Fri, 4 Apr 2003 11:26:14 -0800 +User-Agent: KMail/1.4.3 +Cc: "Tomasz Myrta" , + Robert Treat , + pgsql-sql@postgresql.org, pgsql-performance@postgresql.org +References: <1049403724.13799.5473.camel@camel> + <200304040816.01369.josh@agliodbs.com> + +In-Reply-To: +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304041126.14530.josh@agliodbs.com> +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/63 +X-Sequence-Number: 1569 + +Manfred, + +> I'd be honestly interested in the circumstances where you made that +> observation. + +Hmmmm ... one of my database involves a "crosstab" converstion where there= +=20 +were 13 possible values, and the converted table is heavily indexed. For= +=20 +that case, I found using CASE statements to be slower. + +For your example, how do the statistics change if you increase the number o= +f=20 +levels to 15 and put an index on them? + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-hackers-owner@postgresql.org Fri Apr 4 14:27:30 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6F9DD4758E6 + for ; + Fri, 4 Apr 2003 14:27:28 -0500 (EST) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id BBEAB474E42 + for ; + Fri, 4 Apr 2003 14:27:20 -0500 (EST) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2942672; Fri, 04 Apr 2003 11:27:13 -0800 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Lamar Owen , + "Merlin Moncure" +Subject: Re: [PERFORM] OSS database needed for testing +Date: Fri, 4 Apr 2003 11:27:16 -0800 +User-Agent: KMail/1.4.3 +Cc: +References: <303E00EBDD07B943924382E153890E5434A93B@cuthbert.rcsinc.local> + <200304041408.31175.lamar.owen@wgcr.org> +In-Reply-To: <200304041408.31175.lamar.owen@wgcr.org> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304041127.16441.josh@agliodbs.com> +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/170 +X-Sequence-Number: 37660 + +Lamar, + +> Also check out the cdbs files (which contain the broadcast stuff as well = +as=20 +> more) at /pub/Bureaus/Mass_Media/Databases/cdbs/ (which I would be more= +=20 +> interested in doing, since I am a broadcast engineer by profession....) + +Hey, if you're willing to do the text --> postgres conversions, I'll use=20 +whichever tables you want ... + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 17:57:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EECB24758E6 + for ; + Fri, 4 Apr 2003 17:57:23 -0500 (EST) +Received: from isis.pcis.net (cr.pcis.net [207.18.226.3]) + by postgresql.org (Postfix) with ESMTP id 342E1474E42 + for ; + Fri, 4 Apr 2003 17:57:19 -0500 (EST) +Received: from lyric.ofsloans.com (unverified [209.180.142.225]) by + isis.pcis.net + (Rockliffe SMTPRA 4.5.6) with ESMTP id ; + Fri, 4 Apr 2003 16:57:28 -0600 +Subject: Re: ext3 filesystem / linux 7.3 +From: Will LaShell +To: josh@agliodbs.com +Cc: "scott.marlowe" , + Shankar K , Chris Sutton , + pgsql-performance@postgresql.org +In-Reply-To: <200304031512.45007.josh@agliodbs.com> +References: + <1049407460.22236.93.camel@lyric.ofsloans.com> + <200304031512.45007.josh@agliodbs.com> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-YbMpuQfdPeI2TgdsjqPj" +X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) +Date: 04 Apr 2003 15:57:19 -0700 +Message-Id: <1049497040.1713.6.camel@lyric.ofsloans.com> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-44.3 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/64 +X-Sequence-Number: 1570 + +--=-YbMpuQfdPeI2TgdsjqPj +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +Yes, I think we'd be willing to do that. + +( 480 967 7530 ) is the phone contact for the company, +IT manager is Trevor Mantle +and you can ask for me as well. + +wlashell@outsourcefinancial.com is my work email you can feel free to +use. + +Sincerely, + +Will LaShell + +On Thu, 2003-04-03 at 16:12, Josh Berkus wrote: +> Will, +>=20 +>=20 +> > At any rate we use ext3 on the filesystems and we've had no problems at +> > all with the systems. Everything is stable and runs. We keep the +> > machines running and available 24/7 with scheduled downtime transitions +> > to the redundant servers as we need to for whatever kind of +> > enhancements. +>=20 +> Hey, can we use you as a case study for advocacy.openoffice.org? +>=20 +> --=20 +> -Josh Berkus +>=20 +> ______AGLIO DATABASE SOLUTIONS___________________________ +> Josh Berkus +> Complete information technology josh@agliodbs.com +> and data management solutions (415) 565-7293 +> for law firms, small businesses fax 621-2533 +> and non-profit organizations. San Francisco +>=20 +>=20 +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster + + +--=-YbMpuQfdPeI2TgdsjqPj +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.7 (GNU/Linux) + +iD4DBQA+jg3PZr3R5kgOZd0RAg5+AJ4nRWNHokJvxDTYFWYv5y9C6XfL9wCWIHQt +L6Bcnc1bMQojTEsuthBFPg== +=w1Ha +-----END PGP SIGNATURE----- + +--=-YbMpuQfdPeI2TgdsjqPj-- + + +From pgsql-performance-owner@postgresql.org Fri Apr 4 21:08:23 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5682C475A45 + for ; + Fri, 4 Apr 2003 21:08:22 -0500 (EST) +Received: from email01.aon.at (WARSL401PIP8.highway.telekom.at [195.3.96.97]) + by postgresql.org (Postfix) with SMTP id 5B0A04758E6 + for ; + Fri, 4 Apr 2003 21:08:21 -0500 (EST) +Received: (qmail 636396 invoked from network); 5 Apr 2003 02:08:23 -0000 +Received: from m160p014.dipool.highway.telekom.at (HELO cantor) + ([62.46.9.238]) (envelope-sender ) + by qmail1rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 5 Apr 2003 02:08:23 -0000 +From: Manfred Koizar +To: josh@agliodbs.com +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] can i make this sql query more efficiant? +Date: Sat, 05 Apr 2003 04:08:22 +0200 +Message-ID: +References: <1049403724.13799.5473.camel@camel> + <200304040816.01369.josh@agliodbs.com> + + <200304041126.14530.josh@agliodbs.com> +In-Reply-To: <200304041126.14530.josh@agliodbs.com> +X-Mailer: Forte Agent 1.8/32.548 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-32.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_FORTE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/65 +X-Sequence-Number: 1571 + +On Fri, 4 Apr 2003 11:26:14 -0800, Josh Berkus +wrote: +>For your example, how do the statistics change if you increase the number of +>levels to 15 and put an index on them? + +CREATE TABLE baz (event int, level int); + +INSERT INTO baz SELECT (100*random()+0.5), (15*random()+0.5); +INSERT INTO baz SELECT (100*random()+0.5), (15*random()+0.5) FROM baz; +... +INSERT INTO baz SELECT (100*random()+0.5), (15*random()+0.5) FROM baz; +ANALYSE baz; +CREATE INDEX baz_e ON baz(event); +CREATE INDEX baz_l ON baz(level); +CREATE INDEX baz_el ON baz(event, level); +CREATE INDEX baz_le ON baz(level, event); + +tup cluster case subsel + 8K - 1219.90 msec 70605.93 msec (seq scan) + 8K - 3087.30 msec (seq scan off) + + 16K - 3861.87 msec 161902.36 msec (seq scan) + 16K - 31498.76 msec (seq scan off) + 16K event 2407.72 msec 5773.12 msec + 16K level 2298.08 msec 32752.43 msec + 16K l, e 2318.60 msec 3184.84 msec + + 32K - 6571.57 msec 7381.22 msec + 32K e, l 4584.97 msec 3429.94 msec + 32K l, e 4552.00 msec 64782.59 msec + 32K l, e 4552.98 msec 3544.32 msec (baz_l dropped) + + 64K - 17275.73 msec 26525.24 msec + 64K - 17150.16 msec 26195.87 msec (baz_le dropped) + 64K - 17286.29 msec 656046.24 msec (baz_el dropped) + 64K e, l 9137.88 msec 21809.52 msec + 64K e, l 9183.25 msec 6412.97 msec (baz_e dropped) + 64K e, l 11690.28 msec 10022.44 msec (baz_el dropped) + 64K e, l 11740.54 msec 643046.39 msec (baz_le dropped) + 64K l, e 9437.65 msec 133368.20 msec + 64K l, e 9119.48 msec 6722.00 msec (baz_l dropped) + 64K l, e 9294.68 msec 6663.15 msec (baz_le dropped) + 64K l, e 9259.35 msec 639754.27 msec (baz_el dropped) + +256K - 59809.69 msec 120755.78 msec +256K - 59809.69 msec 114133.34 msec (baz_le dropped) +256K e, l 38506.41 msec 88531.54 msec +256K e, l 49427.43 msec 43544.03 msec (baz_e dropped) +256K l, e 56821.23 msec 575850.14 msec +256K l, e 57462.78 msec 67911.41 msec (baz_l dropped) + +So yes, there are cases where subselect is faster than case, but case +is much more robust regarding correlation and indices. + +Servus + Manfred + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 10:28:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 436AB474E42 + for ; + Mon, 7 Apr 2003 10:28:42 -0400 (EDT) +Received: from lewexch.lewis-stores.com (mail.lewis-stores.com + [196.31.249.242]) + by postgresql.org (Postfix) with ESMTP id 51398475F39 + for ; + Mon, 7 Apr 2003 10:28:29 -0400 (EDT) +Received: by LEWEXCH with Internet Mail Service (5.5.2650.21) + id ; Mon, 7 Apr 2003 16:24:50 +0200 +Message-ID: +From: Howard Oblowitz +To: pgsql-performance@postgresql.org +Subject: Load times on RAID0 compared to RAID5 +Date: Mon, 7 Apr 2003 16:23:03 +0200 +MIME-Version: 1.0 +X-Mailer: Internet Mail Service (5.5.2650.21) +Content-Type: text/plain +X-Spam-Status: No, hits=-6.6 required=5.0 + tests=BAYES_01 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/67 +X-Sequence-Number: 1573 + +We have a perl program that loads data into Postgres version 7.3.1 +using deletes and inserts. + +We find that the load times are about 50% slower when we use a +RAID5 disk system as compared to when we use RAID0 + +Are there any postgres configuration parameters that we can set to improve +the performance on RAID5? + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 10:25:40 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 692E6475B85 + for ; + Mon, 7 Apr 2003 10:25:39 -0400 (EDT) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id 0A5E6474E42 + for ; + Mon, 7 Apr 2003 10:25:38 -0400 (EDT) +Received: (qmail 15483 invoked from network); 7 Apr 2003 14:25:38 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 7 Apr 2003 14:25:38 -0000 +From: "Robert John Shepherd" +To: "'Stephan Szabo'" +Cc: +Subject: Re: [BUGS] Rapid deteriation of performance (might be caused by + tsearch?) in 7.3.2 +Date: Mon, 7 Apr 2003 15:25:38 +0100 +Message-ID: <002801c2fd11$8f893340$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <20030404072355.Q93368-100000@megazone23.bigpanda.com> +X-Spam-Status: No, hits=-10.1 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT,QUOTE_TWICE_1 + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/66 +X-Sequence-Number: 1572 + +> > I've been running this daily: +> > vacuumdb -h localhost -a -z +> > Should I be using the full switch then? +> +> Well, you generally shouldn't need to if the fsm settings are high +enough. +> If you're doing really big updates like update each row of a 1 billion +> row table, you may end up having to do one immediately following that. +> Of course, if you're doing that, performance is probably not your +biggest +> concern. ;) + +Not doing that, no. ;) + + +> Explain analyze'll tell us if the system is changing plans (presumably +to +> a worse one) + +It wasn't, oddly enough. + +I've added a new table that cuts down 85% of the work this query has to +do, and it seems to have helped an awful lot at the moment. Of course +only time will tell. :) + +Thanks for the suggestions. + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 10:36:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7EA50475E9D + for ; + Mon, 7 Apr 2003 10:36:14 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id A3F31475C15 + for ; + Mon, 7 Apr 2003 10:36:12 -0400 (EDT) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 192XjN-00041G-00 + for ; Mon, 07 Apr 2003 10:36:17 -0400 +Received: by dba2 (Postfix, from userid 1019) + id 480D5CCF3; Mon, 7 Apr 2003 10:36:17 -0400 (EDT) +Date: Mon, 7 Apr 2003 10:36:17 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: Load times on RAID0 compared to RAID5 +Message-ID: <20030407143617.GC28340@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/68 +X-Sequence-Number: 1574 + +On Mon, Apr 07, 2003 at 04:23:03PM +0200, Howard Oblowitz wrote: +> We find that the load times are about 50% slower when we use a +> RAID5 disk system as compared to when we use RAID0 + +Well, given that RAID 5 has to do some calculation and RAID 0 +doesn't, I shouldn't think this is very surprising. + +You should let us know what disk subsystem you have, &c. It's +impossible to give any advice on the basis of the little that's here. +RAID performance is linked to its configuration and the hardware and +software in use. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 11:35:22 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 1ABD2475EF0 + for ; + Mon, 7 Apr 2003 11:35:21 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 6E13F474E42 + for ; + Mon, 7 Apr 2003 11:35:18 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h37FXSYQ001487; + Mon, 7 Apr 2003 09:33:28 -0600 (MDT) +Date: Mon, 7 Apr 2003 09:29:48 -0600 (MDT) +From: "scott.marlowe" +To: Howard Oblowitz +Cc: +Subject: Re: Load times on RAID0 compared to RAID5 +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/70 +X-Sequence-Number: 1576 + +On Mon, 7 Apr 2003, Howard Oblowitz wrote: + +> We have a perl program that loads data into Postgres version 7.3.1 +> using deletes and inserts. +> +> We find that the load times are about 50% slower when we use a +> RAID5 disk system as compared to when we use RAID0 +> +> Are there any postgres configuration parameters that we can set to improve +> the performance on RAID5? + +Well, RAID0 SHOULD be about twice as fast as RAID5 for most applications, +maybe even faster for others. + +Of course, RAID0 offers no redundancy, so if any single drive fails your +data disappears in a large puff of smoke. RAID5 can survive a single +drive failure, and that doesn't come for free. + +RAID1 may offer a better compromise of performance and reliability for +many apps than RAID5. Generally RAID0 is fastest, RAID1 is fast but can't +grow to be as big as RAID5, RAID5 handles large parallel access better +than RAID1, RAID1 handles batch processing better than RAID5. + +Mixing them together sometimes helps, sometimes not. RAID1 on top of +RAID0 works pretty well but costs the most per meg stored than most plain +RAID5 or RAID1 setups. + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 11:31:27 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3D7E7475B85 + for ; + Mon, 7 Apr 2003 11:31:26 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 0C238474E42 + for ; + Mon, 7 Apr 2003 11:31:23 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2948765; Mon, 07 Apr 2003 08:31:20 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Howard Oblowitz , + pgsql-performance@postgresql.org +Subject: Re: Load times on RAID0 compared to RAID5 +Date: Mon, 7 Apr 2003 08:31:09 -0700 +User-Agent: KMail/1.4.3 +References: +In-Reply-To: +MIME-Version: 1.0 +Message-Id: <200304070831.09813.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/69 +X-Sequence-Number: 1575 + +Howard, + +> We have a perl program that loads data into Postgres version 7.3.1 +> using deletes and inserts. + +Might I suggest COPY instead? + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Mon Apr 7 13:17:55 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B464F476178 + for ; + Mon, 7 Apr 2003 13:17:53 -0400 (EDT) +Received: from localhost.localdomain (unknown [65.217.53.66]) + by postgresql.org (Postfix) with ESMTP id C60CD475FBA + for ; + Mon, 7 Apr 2003 13:17:44 -0400 (EDT) +Received: from thorn.mmrd.com (thorn.mmrd.com [172.25.10.100]) + by localhost.localdomain (8.12.8/8.12.5) with ESMTP id h37Htakj000670; + Mon, 7 Apr 2003 13:55:36 -0400 +Received: from gnvex001.mmrd.com (gnvex001.mmrd.com [192.168.3.55]) + by thorn.mmrd.com (8.11.6/8.11.6) with ESMTP id h37HHZx29153; + Mon, 7 Apr 2003 13:17:35 -0400 +Received: from camel.mmrd.com ([172.25.5.213]) by gnvex001.mmrd.com with SMTP + (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) + id F3HTM18W; Mon, 7 Apr 2003 13:17:35 -0400 +Subject: Re: ext3 filesystem / linux 7.3 +From: Robert Treat +To: Shankar K +Cc: "scott.marlowe" , + Chris Sutton , pgsql-performance@postgresql.org +In-Reply-To: <20030403194552.914.qmail@web21103.mail.yahoo.com> +References: <20030403194552.914.qmail@web21103.mail.yahoo.com> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.8 +Date: 07 Apr 2003 13:17:35 -0400 +Message-Id: <1049735855.8344.8807.camel@camel> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-35.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/71 +X-Sequence-Number: 1577 + +We've had 2 crashes on red hat 7.3 in about 9 months of running. Both +instances required manual power off/on of the server, but everything +came up nice and ready to go. The problems seemed to stem from i/o load +with the kernel (not postgresql specific), but should be resolved with +the latest Red Hat kernel. If you search on buffer_jdirty in bugzilla +you'll see a couple of reports. + +Robert Treat + +On Thu, 2003-04-03 at 14:45, Shankar K wrote: +> Hi Scott, +> +> Could you please share with us the problems you had +> with linux 7.3 +> +> would be really interested to know the kernel configs +> and ext3 filesystem modes +> +> Shankar +> +> --- "scott.marlowe" wrote: +> > On Thu, 3 Apr 2003, Chris Sutton wrote: +> > +> > > On Wed, 2 Apr 2003, Josh Berkus wrote: +> > > +> > > > > I had previously understood that ext3 was a +> > bad thing with PostgreSQL and I +> > > > > went way above and beyond to create it on an +> > Ext2 filesystem (the only one +> > > > > on the server) and mount that. +> > > +> > > We recently started using Postgres on a new +> > database server running RH 7.3 +> > > and ext3. Due to some kernel problems the machine +> > would crash at random +> > > times. Each time it crashed it came back up +> > extremly easily with no data +> > > loss. If we were on ext2 coming back up after a +> > crash probably wouldn't +> > > have been quite as easy. +> > > +> > > We have since given up on RH 7.3 and gone with RH +> > Enterprise ES. Just an +> > > FIY for any of you out there thinking about moving +> > to RH 7.3 or those that +> > > are having problems with 7.3 and ext3. +> > +> > We're still running RH 7.2 due to issues we had with +> > 7.3 as well. +> > + + +From pgsql-sql-owner@postgresql.org Tue Apr 8 10:58:56 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 39D31474E42 + for ; Tue, 8 Apr 2003 10:58:55 -0400 (EDT) +Received: from smtp-out.net.ipl.pt (31.220.137.193.in-addr.arpa + [193.137.220.31]) + by postgresql.org (Postfix) with ESMTP id E8CFD4763B6 + for ; Tue, 8 Apr 2003 10:58:52 -0400 (EDT) +Received: (qmail 15518 invoked by uid 508); 8 Apr 2003 15:58:56 +0100 +Received: from rutes@eselx.ipl.pt by smtp-int.net.ipl.pt by uid 505 with + qmail-scanner + (sophie: 2.10/3.64. Clear:. Processed in 0.04692 secs); + 08 Apr 2003 14:58:56 -0000 +X-IPLNet-RcptTo: pgsql-sql@postgresql.org +Received: from matrix.eselx.ipl.pt (193.137.237.148) + by 0 with SMTP; 8 Apr 2003 15:58:55 +0100 +Received: from [172.21.3.60] (helo=eselx.ipl.pt) + by matrix.eselx.ipl.pt with esmtp (Exim 3.35 #1 (Debian)) + id 192uYi-0007Yt-00 + for ; Tue, 08 Apr 2003 15:58:48 +0100 +Message-ID: <3E92E3B1.7070405@eselx.ipl.pt> +Date: Tue, 08 Apr 2003 15:58:57 +0100 +From: rute solipa +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; + rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: "pgsql-sql@postgresql.org" +Subject: help need it +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-11.7 required=5.0 + tests=BAYES_10,TO_ADDRESS_EQ_REAL,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/115 +X-Sequence-Number: 12816 + +i've an oracle query: + +Select tb_users.ds_description, tb_users.cd_role, tb_users.cd_user, +tb_users.ds_login, tb_monitores.cod_equipa from tb_users, tb_monitores +where ds_login like 'varLogin' and ds_password like 'varPassword' and +tb_users.cd_user = tb_monitores.cd_user(+) + +how can i transform it to an postgresql query? + + +best regards + +etur + + +From pgsql-sql-owner@postgresql.org Tue Apr 8 11:16:32 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E623D476380 + for ; Tue, 8 Apr 2003 11:16:31 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id D0E2D4763A2 + for ; Tue, 8 Apr 2003 11:16:30 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 5E0BCD609; Tue, 8 Apr 2003 08:16:34 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 4D8515C0A; Tue, 8 Apr 2003 08:16:34 -0700 (PDT) +Date: Tue, 8 Apr 2003 08:16:34 -0700 (PDT) +From: Stephan Szabo +To: rute solipa +Cc: "pgsql-sql@postgresql.org" +Subject: Re: help need it +In-Reply-To: <3E92E3B1.7070405@eselx.ipl.pt> +Message-ID: <20030408081439.P50886-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/116 +X-Sequence-Number: 12817 + + +On Tue, 8 Apr 2003, rute solipa wrote: + +> i've an oracle query: +> +> Select tb_users.ds_description, tb_users.cd_role, tb_users.cd_user, +> tb_users.ds_login, tb_monitores.cod_equipa from tb_users, tb_monitores +> where ds_login like 'varLogin' and ds_password like 'varPassword' and +> tb_users.cd_user = tb_monitores.cd_user(+) +> +> how can i transform it to an postgresql query? + +Should be something like: + +Select tb_users.ds_description, tb_users.cd_role, tb_users.cd_user, +tb_users.ds_login, tb_monitores.cod_equipa from tb_users left +outer join tb_monitores using (cd_user) +where ds_login like 'varLogin' and ds_password like 'varPassword'; + + +From pgsql-sql-owner@postgresql.org Tue Apr 8 11:23:41 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 733994762F1 + for ; Tue, 8 Apr 2003 11:23:40 -0400 (EDT) +Received: from matrix.gatewaynet.com (unknown [217.19.69.50]) + by postgresql.org (Postfix) with ESMTP id 53C774762E1 + for ; Tue, 8 Apr 2003 11:23:39 -0400 (EDT) +Received: from matrix.gatewaynet.com (matrix.gatewaynet.com [217.19.69.50] + (may be forged)) + by matrix.gatewaynet.com (8.12.5/8.12.5) with ESMTP id h38JeeIs009771; + Tue, 8 Apr 2003 17:40:40 -0200 +Received: from localhost (achill@localhost) + by matrix.gatewaynet.com (8.12.5/8.12.5/Submit) with ESMTP id + h38JeeRb009767; Tue, 8 Apr 2003 17:40:40 -0200 +Date: Tue, 8 Apr 2003 17:40:39 -0200 (GMT+2) +From: Achilleus Mantzios +To: rute solipa +Cc: "pgsql-sql@postgresql.org" +Subject: Re: help need it +In-Reply-To: <3E92E3B1.7070405@eselx.ipl.pt> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES,SIGNATURE_LONG_DENSE, + USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/117 +X-Sequence-Number: 12818 + +On Tue, 8 Apr 2003, rute solipa wrote: + +> i've an oracle query: +> +> Select tb_users.ds_description, tb_users.cd_role, tb_users.cd_user, +> tb_users.ds_login, tb_monitores.cod_equipa from tb_users, tb_monitores +> where ds_login like 'varLogin' and ds_password like 'varPassword' and +> tb_users.cd_user = tb_monitores.cd_user(+) +> +> how can i transform it to an postgresql query? + +Can you check the postgresql manual if the (+) operator +means something related to OUTER joins? +If yes then use [LEFT|RIGHT] OUTER JOIN of postgresql. + +> +> +> best regards +> +> etur +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster +> + +-- +================================================================== +Achilleus Mantzios +S/W Engineer +IT dept +Dynacom Tankers Mngmt +Nikis 4, Glyfada +Athens 16610 +Greece +tel: +30-210-8981112 +fax: +30-210-8981877 +email: achill@matrix.gatewaynet.com + mantzios@softlab.ece.ntua.gr + + +From pgsql-general-owner@postgresql.org Tue Apr 8 15:59:29 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 7199D4762D7; Tue, 8 Apr 2003 15:59:28 -0400 (EDT) +Received: from news.hub.org (news.hub.org [64.49.215.80]) + by postgresql.org (Postfix) with ESMTP + id E817E4762CF; Tue, 8 Apr 2003 15:59:27 -0400 (EDT) +Received: by news.hub.org (Postfix, from userid 8) + id D7B1943A89E; Tue, 8 Apr 2003 15:59:27 -0400 (EDT) +From: "Denis" +X-Newsgroups: comp.databases.postgresql.general, + comp.databases.postgresql.performance, + comp.databases.postgresql.sql +Subject: Yet Another (Simple) Case of Index not used +Date: Tue, 8 Apr 2003 12:57:16 -0700 +Organization: Hub.Org Networking Services (http://www.hub.org) +Lines: 68 +Message-ID: +X-Complaints-To: usenet@news.hub.org +X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +To: pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +X-Spam-Status: No, hits=-5.8 required=5.0 + tests=BAYES_10 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/526 +X-Sequence-Number: 40591 + +Hi there, +I'm running into a quite puzzling simple example where the index I've +created on a fairly big table (465K entries) is not used, against all common +sense expectations: +The query I am trying to do (fast) is: + +select count(*) from addresses; + +This takes more than a second to complete, because, as the 'explain' command +shows me, +the index created on 'addresses' is not used, and a seq scan is being used. +One would assume that the creation of an index would allow the counting of +the number of entries in a table to be instantanous? + +Here are the details: + +* Using the latest postgresql 7.3.2 release, built and installed from +sources on a Linux box, under Red Hat 8.0 + +* I have an 'addresses' table defined as: +Columm | Type +------------------------------- +address | text +city | char var (20) +zip | char var (5) +state | char var (2) +Unique keys: addresses_idx + +* I have created a unique index 'addresses_idx' on (address, city, zip, +state): +\d addresses_idx; +Index "addresses_idx" +Columm | Type +------------------------------- +address | text +city | char var (20) +zip | char var (5) +state | char var (2) +unique btree + +* I did (re)create the index several times +* I did run the vacuum analyse command several times +* I forced enable_indexscan to true +* I forced enable_seqscan to false + +Despite of all of this, each time I try: +===> explain select count(*) from addresses; +I get the following: +===> NOTICE: QUERY PLAN: +===> +===> Aggregate (cost=100012799.89..100012799.89 rows=1 width=0) +===> -> Seq Scan on addresses (cost=100000000.00..100011635.11 rows=465911 +width=0) + +Quite puzzling, isn't it? +I've searched a bunch of mailing lists and websites, and found many reports +of special cases where it could be argued that the planner may have had a +case for choosing seq scanning over idx scanning, but unless I am missing +some fundamental concept, there's something wrong here. +Any suggestion anyone? +Thanks, + +Denis +denis@next2me.com + + +From pgsql-general-owner@postgresql.org Tue Apr 8 16:23:21 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id B28F94758E6; Tue, 8 Apr 2003 16:23:20 -0400 (EDT) +Received: from snoopy.oit.edu (snoopy.OIT.EDU [140.211.135.12]) + by postgresql.org (Postfix) with ESMTP + id B61B9474E42; Tue, 8 Apr 2003 16:23:19 -0400 (EDT) +Received: from cvc.net (purvine-141-62.oit.edu [140.211.141.62]) + by snoopy.oit.edu (8.12.9/8.12.9/OIT-4.0) with ESMTP id h38KNJGM007905; + Tue, 8 Apr 2003 13:23:19 -0700 +Message-ID: <3E933048.4000805@cvc.net> +Date: Tue, 08 Apr 2003 13:25:44 -0700 +From: Dennis Gearon +Reply-To: gearond@cvc.net +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; + rv:1.3b) Gecko/20030210 +X-Accept-Language: en-us, ru +MIME-Version: 1.0 +To: Denis +Cc: pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +Subject: Re: Yet Another (Simple) Case of Index not used +References: +In-Reply-To: +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-38.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/527 +X-Sequence-Number: 40592 + +as I remember, mysql keeps the record count in a variable and is instantaneaous +with that kind of query. Recent posts suggest the Postgres does not keep that +variable and has to do the seq scan. + +Denis wrote: +> Hi there, +> I'm running into a quite puzzling simple example where the index I've +> created on a fairly big table (465K entries) is not used, against all common +> sense expectations: +> The query I am trying to do (fast) is: +> +> select count(*) from addresses; +> +> This takes more than a second to complete, because, as the 'explain' command +> shows me, +> the index created on 'addresses' is not used, and a seq scan is being used. +> One would assume that the creation of an index would allow the counting of +> the number of entries in a table to be instantanous? +> +> Here are the details: +> +> * Using the latest postgresql 7.3.2 release, built and installed from +> sources on a Linux box, under Red Hat 8.0 +> +> * I have an 'addresses' table defined as: +> Columm | Type +> ------------------------------- +> address | text +> city | char var (20) +> zip | char var (5) +> state | char var (2) +> Unique keys: addresses_idx +> +> * I have created a unique index 'addresses_idx' on (address, city, zip, +> state): +> \d addresses_idx; +> Index "addresses_idx" +> Columm | Type +> ------------------------------- +> address | text +> city | char var (20) +> zip | char var (5) +> state | char var (2) +> unique btree +> +> * I did (re)create the index several times +> * I did run the vacuum analyse command several times +> * I forced enable_indexscan to true +> * I forced enable_seqscan to false +> +> Despite of all of this, each time I try: +> ===> explain select count(*) from addresses; +> I get the following: +> ===> NOTICE: QUERY PLAN: +> ===> +> ===> Aggregate (cost=100012799.89..100012799.89 rows=1 width=0) +> ===> -> Seq Scan on addresses (cost=100000000.00..100011635.11 rows=465911 +> width=0) +> +> Quite puzzling, isn't it? +> I've searched a bunch of mailing lists and websites, and found many reports +> of special cases where it could be argued that the planner may have had a +> case for choosing seq scanning over idx scanning, but unless I am missing +> some fundamental concept, there's something wrong here. +> Any suggestion anyone? +> Thanks, +> +> Denis +> denis@next2me.com +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the unregister command +> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) +> + + +From pgsql-general-owner@postgresql.org Tue Apr 8 16:26:25 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 795FE4758E6; Tue, 8 Apr 2003 16:26:24 -0400 (EDT) +Received: from voyager.corporate.connx.com (unknown [66.228.214.131]) + by postgresql.org (Postfix) with ESMTP + id B65EE474E42; Tue, 8 Apr 2003 16:26:23 -0400 (EDT) +content-class: urn:content-classes:message +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +Subject: Re: Yet Another (Simple) Case of Index not used +X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 +Date: Tue, 8 Apr 2003 13:26:21 -0700 +Message-ID: + +X-MS-Has-Attach: +X-MS-TNEF-Correlator: +Thread-Topic: [GENERAL] Yet Another (Simple) Case of Index not used +Thread-Index: AcL+CppcOx7rQQ2DRIG4S7Ej0yTW3AAAd95g +From: "Dann Corbit" +To: "Denis" , , + , +X-Spam-Status: No, hits=-8.6 required=5.0 + tests=BAYES_01,QUOTED_EMAIL_TEXT,RCVD_IN_RFCI version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/528 +X-Sequence-Number: 40593 + +> -----Original Message----- +> From: Denis [mailto:denis@next2me.com]=20 +> Sent: Tuesday, April 08, 2003 12:57 PM +> To: pgsql-performance@postgresql.org;=20 +> pgsql-general@postgresql.org; pgsql-sql@postgresql.org +> Subject: [GENERAL] Yet Another (Simple) Case of Index not used +>=20 +>=20 +> Hi there, +> I'm running into a quite puzzling simple example where the=20 +> index I've created on a fairly big table (465K entries) is=20 +> not used, against all common sense expectations: The query I=20 +> am trying to do (fast) is: +>=20 +> select count(*) from addresses; +>=20 +> This takes more than a second to complete, because, as the=20 +> 'explain' command shows me, the index created on 'addresses'=20 +> is not used, and a seq scan is being used.=20 + +As well it should be. + +> One would assume=20 +> that the creation of an index would allow the counting of the=20 +> number of entries in a table to be instantanous? + +Traversing the index to perform the count will definitely make the query +many times slower. + +A general rule of thumb (not sure if it is true with PostgreSQL) is that +if you have to traverse more than 10% of the data with an index then a +full table scan will be faster. This is especially true when there is +highly redundant data in the index fields. If there were an index on +bit data type, and you have half and half 1 and 0, an index scan of the +table will be disastrous. + +To simply scan the table, we will just sequentially read pages until the +data is exhausted. If we follow the index, we will randomly jump from +page to page, defeating the read buffering. +[snip] + + +From pgsql-general-owner@postgresql.org Tue Apr 8 16:42:22 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id B4C0A476315; Tue, 8 Apr 2003 16:42:20 -0400 (EDT) +Received: from snoopy.oit.edu (snoopy.OIT.EDU [140.211.135.12]) + by postgresql.org (Postfix) with ESMTP + id 8FADD476302; Tue, 8 Apr 2003 16:42:19 -0400 (EDT) +Received: from cvc.net (purvine-141-62.oit.edu [140.211.141.62]) + by snoopy.oit.edu (8.12.9/8.12.9/OIT-4.0) with ESMTP id h38KgEGM010079; + Tue, 8 Apr 2003 13:42:14 -0700 +Message-ID: <3E93348C.20208@cvc.net> +Date: Tue, 08 Apr 2003 13:43:56 -0700 +From: Dennis Gearon +Reply-To: gearond@cvc.net +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; + rv:1.3b) Gecko/20030210 +X-Accept-Language: en-us, ru +MIME-Version: 1.0 +To: Dann Corbit +Cc: Denis , pgsql-performance@postgresql.org, + pgsql-general@postgresql.org, pgsql-sql@postgresql.org +Subject: Re: Yet Another (Simple) Case of Index not used +References: + +In-Reply-To: + +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-38.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/530 +X-Sequence-Number: 40595 + +from mysql manual: +------------------------------------------------------------- +"COUNT(*) is optimized to return very quickly if the SELECT retrieves from one +table, no other columns are retrieved, and there is no WHERE clause. For example: + +mysql> select COUNT(*) from student;" +------------------------------------------------------------- + +A nice little optimization, maybe not possible in a MVCC system. + +Dann Corbit wrote: +>>-----Original Message----- +>>From: Denis [mailto:denis@next2me.com] +>>Sent: Tuesday, April 08, 2003 12:57 PM +>>To: pgsql-performance@postgresql.org; +>>pgsql-general@postgresql.org; pgsql-sql@postgresql.org +>>Subject: [GENERAL] Yet Another (Simple) Case of Index not used +>> +>> +>>Hi there, +>>I'm running into a quite puzzling simple example where the +>>index I've created on a fairly big table (465K entries) is +>>not used, against all common sense expectations: The query I +>>am trying to do (fast) is: +>> +>>select count(*) from addresses; +>> +>>This takes more than a second to complete, because, as the +>>'explain' command shows me, the index created on 'addresses' +>>is not used, and a seq scan is being used. +> +> +> As well it should be. +> +> +>>One would assume +>>that the creation of an index would allow the counting of the +>>number of entries in a table to be instantanous? +> +> +> Traversing the index to perform the count will definitely make the query +> many times slower. +> +> A general rule of thumb (not sure if it is true with PostgreSQL) is that +> if you have to traverse more than 10% of the data with an index then a +> full table scan will be faster. This is especially true when there is +> highly redundant data in the index fields. If there were an index on +> bit data type, and you have half and half 1 and 0, an index scan of the +> table will be disastrous. +> +> To simply scan the table, we will just sequentially read pages until the +> data is exhausted. If we follow the index, we will randomly jump from +> page to page, defeating the read buffering. +> [snip] +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: Have you searched our list archives? +> +> http://archives.postgresql.org +> + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 17:52:52 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3145F475E14 + for ; + Tue, 8 Apr 2003 17:52:51 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id AFB1A4758E6 + for ; + Tue, 8 Apr 2003 17:52:49 -0400 (EDT) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2951738; Tue, 08 Apr 2003 14:52:44 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Denis" , pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Tue, 8 Apr 2003 14:52:40 -0700 +User-Agent: KMail/1.4.3 +References: +In-Reply-To: +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304081452.40424.josh@agliodbs.com> +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/75 +X-Sequence-Number: 1581 + +Dennis, + +> I'm running into a quite puzzling simple example where the index I've +> created on a fairly big table (465K entries) is not used, against all com= +mon +> sense expectations: +> The query I am trying to do (fast) is: +>=20 +> select count(*) from addresses; + +PostgreSQL is currently unable to use indexes on aggregate queries. This = +is=20 +because of two factors: +1) MVCC means that the number of rows must be recalculated for each=20 +connection's current transaction, and cannot be "cached" anywhere by the=20 +database system; +2) Our extensible model of user-defined aggregates means that each aggregat= +e=20 +is a "black box" whose internal operations are invisible to the planner. + +This is a known performance issue for Postgres, and I believe that a couple= + of=20 +people on Hackers are looking at modifying aggregate implementation for 8.0= +=20 +to use appropriate available indexes, at least for MIN, MAX and COUNT. Unt= +il=20 +then, you will need to either put up with the delay, or create a=20 +trigger-driven aggregates caching table. + +If you are trying to do a correlated count, like "SELECT type, count(*) fro= +m=20 +aggregates GROUP BY type", Tom Lane has already added a hash-aggregates=20 +structure in the 7.4 source that will speed this type of query up=20 +considerably for systems with lots of RAM. + +(PS: in the future, please stick to posting questions to one list at a time= +,=20 +thanks) + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 19:22:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5D2D24758E6 + for ; + Tue, 8 Apr 2003 19:22:45 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id A29CE474E42 + for ; + Tue, 8 Apr 2003 19:22:44 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Tue, 08 Apr 2003 16:22:47 -0700 +Date: Tue, 8 Apr 2003 16:22:47 -0700 +From: Kevin Brown +To: pgsql-performance@postgresql.org +Cc: Josh Berkus +Subject: Re: ext3 filesystem / linux 7.3 +Message-ID: <20030408232247.GH1847@filer> +Mail-Followup-To: Kevin Brown , + pgsql-performance@postgresql.org, Josh Berkus +References: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> + <200304030852.34194.josh@agliodbs.com> + <0b7a01c2fa04$2d299bf0$0b02a8c0@pointhere.net> + <200304030943.06406.josh@agliodbs.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <200304030943.06406.josh@agliodbs.com> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/76 +X-Sequence-Number: 1582 + +Josh Berkus wrote: +> Jeffery, +> +> > Can't we generate data? Random data stored in random formats at random +> > sizes would stress the file system wouldn't it? +> +> In my experience, randomly generated data tends to resemble real data very +> little in distribution patterns and data types. This is one of the +> limitations of PGBench. + +Okay, from this it sounds like what we need is information on the data +types typically used for real world applications and information on +the the distribution patterns for each type (the latter could get +quite complex and varied, I'm sure, but since we're after something +that's typical, we only need a few examples). + +So perhaps the first step in this is to write something that will show +what the distribution pattern for data in a table is? With that +information, we *could* randomly generate data that would conform to +the statistical patterns seen in the real world. + +In fact, even though the databases you have access to are all +proprietary, I'm pretty sure their owners would agree to let you run a +program that would gather statistical distribution about it. Then (as +long as they agree) you could copy the schema itself, recreate it on +the test system, and randomly generate the data. + + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-general-owner@postgresql.org Tue Apr 8 19:46:35 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 3C2CE475E14; Tue, 8 Apr 2003 19:46:34 -0400 (EDT) +Received: from svana.org (svana.org [203.20.62.76]) + by postgresql.org (Postfix) with ESMTP + id 52926474E42; Tue, 8 Apr 2003 19:46:33 -0400 (EDT) +Received: from kleptog by svana.org with local (Exim 3.35 #1 (Debian)) + id 1932nH-0006P3-00; Wed, 09 Apr 2003 09:46:23 +1000 +Date: Wed, 9 Apr 2003 09:46:23 +1000 +From: Martijn van Oosterhout +To: Denis +Cc: pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +Subject: Re: Yet Another (Simple) Case of Index not used +Message-ID: <20030408234623.GD15928@svana.org> +Reply-To: Martijn van Oosterhout +Mail-Followup-To: Denis , + pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +References: +Mime-Version: 1.0 +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; boundary="IMjqdzrDRly81ofr" +Content-Disposition: inline +In-Reply-To: +User-Agent: Mutt/1.3.28i +X-PGP-Key-ID: Length=1024; ID=0x0DC67BE6 +X-PGP-Key-Fingerprint: 295F A899 A81A 156D B522 48A7 6394 F08A 0DC6 7BE6 +X-PGP-Key-URL: +X-Spam-Status: No, hits=-45.1 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/544 +X-Sequence-Number: 40609 + +--IMjqdzrDRly81ofr +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +Content-Transfer-Encoding: quoted-printable + +On Tue, Apr 08, 2003 at 12:57:16PM -0700, Denis wrote: +> The query I am trying to do (fast) is: +>=20 +> select count(*) from addresses; +>=20 +> This takes more than a second to complete, because, as the 'explain' comm= +and +> shows me, +> the index created on 'addresses' is not used, and a seq scan is being use= +d. +> One would assume that the creation of an index would allow the counting of +> the number of entries in a table to be instantanous? + +Incorrect assumption. select count(*) can produce different results in +different backends depending on the current state of the active +transactions. +--=20 +Martijn van Oosterhout http://svana.org/kleptog/ +> "the West won the world not by the superiority of its ideas or values or +> religion but rather by its superiority in applying organized violence. +> Westerners often forget this fact, non-Westerners never do." +> - Samuel P. Huntington + +--IMjqdzrDRly81ofr +Content-Type: application/pgp-signature +Content-Disposition: inline + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.6 (GNU/Linux) +Comment: For info see http://www.gnupg.org + +iD8DBQE+k19PY5Twig3Ge+YRAs7pAJ4kxoQQnRu1zQeCzfB+8lRA4XgTtQCeMb1T +m2DuiE8HICjO5qVCcVKdgUI= +=LkBi +-----END PGP SIGNATURE----- + +--IMjqdzrDRly81ofr-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 20:12:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 66B6F4758F1 + for ; + Tue, 8 Apr 2003 20:12:26 -0400 (EDT) +Received: from localhost.localdomain + (adsl-216-103-208-155.dsl.snfc21.pacbell.net [216.103.208.155]) + by postgresql.org (Postfix) with ESMTP id 0DB50474E42 + for ; + Tue, 8 Apr 2003 20:12:12 -0400 (EDT) +Received: from flipper5 (flipper5.next2me.com [192.168.0.3]) + by localhost.localdomain (8.12.8/8.12.8) with SMTP id h390DYgL032299; + Tue, 8 Apr 2003 17:13:34 -0700 +Reply-To: +From: "Denis @ Next2Me" +To: "Martijn van Oosterhout" , "Denis" +Cc: +Subject: Re: [GENERAL] Yet Another (Simple) Case of Index not used +Date: Tue, 8 Apr 2003 17:10:01 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <20030408234623.GD15928@svana.org> +X-Spam-Status: No, hits=-14.7 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/78 +X-Sequence-Number: 1584 + +Interesting generic response. In other words, "it all depends". +Well, a de facto observation is: "In my case, it's always much slower with, say, mysql". +Understand me, I don't mean to be starting a performance comparaison mysql vs postgresql, +which is probably an old subject, I am just looking for a solution to solve this type +of performance issues, ie the generic cases: +select count(*) from addresses where address is like 'pattern%'; +Which are very fast on mysql, and very slow on postgresql. +Understood, it will always depend on some parameters, but the real question is: how +much control does one have over those parameters, and how does one tweak them to reach +optimal performance? + +D. + + + + + + > -----Original Message----- + > From: pgsql-performance-owner@postgresql.org + > [mailto:pgsql-performance-owner@postgresql.org]On Behalf Of Martijn van + > Oosterhout + > Sent: Tuesday, April 08, 2003 4:46 PM + > To: Denis + > Cc: pgsql-performance@postgresql.org; pgsql-general@postgresql.org; + > pgsql-sql@postgresql.org + > Subject: Re: [PERFORM] [GENERAL] Yet Another (Simple) Case of Index not + > used + > + > + > On Tue, Apr 08, 2003 at 12:57:16PM -0700, Denis wrote: + > > The query I am trying to do (fast) is: + > > + > > select count(*) from addresses; + > > + > > This takes more than a second to complete, because, as the 'explain' command + > > shows me, + > > the index created on 'addresses' is not used, and a seq scan is being used. + > > One would assume that the creation of an index would allow the counting of + > > the number of entries in a table to be instantanous? + > + > Incorrect assumption. select count(*) can produce different results in + > different backends depending on the current state of the active + > transactions. + > -- + > Martijn van Oosterhout http://svana.org/kleptog/ + > > "the West won the world not by the superiority of its ideas or values or + > > religion but rather by its superiority in applying organized violence. + > > Westerners often forget this fact, non-Westerners never do." + > > - Samuel P. Huntington + > + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 20:23:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B18D14758E6 + for ; + Tue, 8 Apr 2003 20:23:27 -0400 (EDT) +Received: from localhost.localdomain + (adsl-216-103-208-155.dsl.snfc21.pacbell.net [216.103.208.155]) + by postgresql.org (Postfix) with ESMTP id 82369474E42 + for ; + Tue, 8 Apr 2003 20:23:26 -0400 (EDT) +Received: from flipper5 (flipper5.next2me.com [192.168.0.3]) + by localhost.localdomain (8.12.8/8.12.8) with SMTP id h390OmgL032444; + Tue, 8 Apr 2003 17:24:48 -0700 +Reply-To: +From: "Denis @ Next2Me" +To: , "Denis" , + +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Tue, 8 Apr 2003 17:21:16 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <200304081452.40424.josh@agliodbs.com> +X-Spam-Status: No, hits=-14.7 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/79 +X-Sequence-Number: 1585 + +Josh, + +I am no database expert, and even less knowledgeable about the internals +of postgresql, so I'll trust you on the 2 points you make below. + +Are you saying the 7.4 'group by' trick would be faster than the simple select count(*)? +That seems hard to believe, being that the request now has to fetch / sort the data. +I must be missing something. + +The kind of requests that I am really interested in are: +select count(*) from table where table.column like 'pattern%' +These seems to go much master on mysql (which I guess it not a MVCC database? or wasn't +the Innobase supposed to make it so?), than on postgresql. + +So, in the meantime, I've decided to split up my data into two sets, +the static big tables which are handled by mysql, and the rest of it handled +by postgresql.... + + + +ps: apologies for the cross-posting. + + > -----Original Message----- + > From: Josh Berkus [mailto:josh@agliodbs.com] + > Sent: Tuesday, April 08, 2003 2:53 PM + > To: Denis; pgsql-performance@postgresql.org + > Subject: Re: [SQL] Yet Another (Simple) Case of Index not used + > + > + > Dennis, + > + > > I'm running into a quite puzzling simple example where the index I've + > > created on a fairly big table (465K entries) is not used, against all common + > > sense expectations: + > > The query I am trying to do (fast) is: + > > + > > select count(*) from addresses; + > + > PostgreSQL is currently unable to use indexes on aggregate queries. This is + > because of two factors: + > 1) MVCC means that the number of rows must be recalculated for each + > connection's current transaction, and cannot be "cached" anywhere by the + > database system; + > 2) Our extensible model of user-defined aggregates means that each aggregate + > is a "black box" whose internal operations are invisible to the planner. + > + > This is a known performance issue for Postgres, and I believe that a couple of + > people on Hackers are looking at modifying aggregate implementation for 8.0 + > to use appropriate available indexes, at least for MIN, MAX and COUNT. Until + > then, you will need to either put up with the delay, or create a + > trigger-driven aggregates caching table. + > + > If you are trying to do a correlated count, like "SELECT type, count(*) from + > aggregates GROUP BY type", Tom Lane has already added a hash-aggregates + > structure in the 7.4 source that will speed this type of query up + > considerably for systems with lots of RAM. + > + > (PS: in the future, please stick to posting questions to one list at a time, + > thanks) + > + > -- + > -Josh Berkus + > Aglio Database Solutions + > San Francisco + > + + +From pgsql-general-owner@postgresql.org Wed Apr 9 12:13:43 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id ED4514758E6 + for ; + Tue, 8 Apr 2003 20:44:51 -0400 (EDT) +Received: from clam.niwa.co.nz (clam.niwa.cri.nz [202.36.29.1]) + by postgresql.org (Postfix) with ESMTP id 8E84A474E42 + for ; + Tue, 8 Apr 2003 20:44:50 -0400 (EDT) +Received: from storm.niwa.co.nz (storm.niwa.co.nz [192.168.59.10]) + by clam.niwa.co.nz (8.12.6p2/8.12.3) with ESMTP id h390imuX064083; + Wed, 9 Apr 2003 12:44:49 +1200 (NZST) + (envelope-from b.wood@niwa.co.nz) +Received: from localhost (wood@localhost) + by storm.niwa.co.nz (8.11.6/8.11.6) with ESMTP id h390im634386; + Wed, 9 Apr 2003 12:44:48 +1200 (NZST) + (envelope-from wood@storm.niwa.co.nz) +Date: Wed, 9 Apr 2003 12:44:48 +1200 (NZST) +From: Brent Wood +To: pgsql-general@postgresql.org +Cc: Denis +Subject: Re: Yet Another (Simple) Case of Index not used +In-Reply-To: <20030408234623.GD15928@svana.org> +Message-ID: <20030409123856.Q34167-100000@storm.niwa.co.nz> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/591 +X-Sequence-Number: 40656 + + + +On Wed, 9 Apr 2003, Martijn van Oosterhout wrote: + +> On Tue, Apr 08, 2003 at 12:57:16PM -0700, Denis wrote: +> > The query I am trying to do (fast) is: +> > +> > select count(*) from addresses; +> > +> > This takes more than a second to complete, because, as the 'explain' command +> > shows me, +> > the index created on 'addresses' is not used, and a seq scan is being used. +> > One would assume that the creation of an index would allow the counting of +> > the number of entries in a table to be instantanous? +> +> Incorrect assumption. select count(*) can produce different results in +> different backends depending on the current state of the active +> transactions. + +Some thoughts: + +Select count(*) is often applied to views, and may take some time +depending on the underlying query. + +However, for a single table, I would have thought that if there are no +write locks or open transactions for the table, the index would return a +faster result than a scan? Is there room for some optimisation here? + +Does count() work faster, poss using the unique index on the +key (for non-composite keys)? + + +Cheers + Brent Wood + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 22:00:10 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9CC41475F3D + for ; + Tue, 8 Apr 2003 22:00:06 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 0B50B474E42 + for ; + Tue, 8 Apr 2003 21:59:34 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id ED552D60B; Tue, 8 Apr 2003 18:59:37 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id E30EE5C0B; Tue, 8 Apr 2003 18:59:37 -0700 (PDT) +Date: Tue, 8 Apr 2003 18:59:37 -0700 (PDT) +From: Stephan Szabo +To: "Denis @ Next2Me" +Cc: , +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-Reply-To: +Message-ID: <20030408185412.C57783-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/80 +X-Sequence-Number: 1586 + + +On Tue, 8 Apr 2003, Denis @ Next2Me wrote: + +> The kind of requests that I am really interested in are: +> select count(*) from table where table.column like 'pattern%' + +If you think an index scan should be faster, you can try +set enable_seqscan=off; +and see if that changes the plan generated by explain and with analyze +you can compare the time used. Without information on the estimated +selectivity it's hard to say what's right. + +If it doesn't use the index (ie, it's still using a sequential scan) +after the enable_seqscan=off it's likely that you didn't initdb in "C" +locale in which case like won't use indexes currently (you can see the +archives for long description, but the short one is that some of the +locale rules can cause problems with using the index). + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 22:35:32 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 727F84760CC + for ; + Tue, 8 Apr 2003 22:35:31 -0400 (EDT) +Received: from houston.familyhealth.com.au (unknown [203.59.48.253]) + by postgresql.org (Postfix) with ESMTP id 8671B475E77 + for ; + Tue, 8 Apr 2003 22:35:27 -0400 (EDT) +Received: (from root@localhost) + by houston.familyhealth.com.au (8.11.6p2/8.11.6) id h392ZVK50833 + for pgsql-performance@postgresql.org; + Wed, 9 Apr 2003 10:35:31 +0800 (WST) + (envelope-from chriskl@familyhealth.com.au) +Received: from mariner (mariner.internal [192.168.0.101]) + by houston.familyhealth.com.au (8.11.6p2/8.9.3) with SMTP id + h392ZCx50663; Wed, 9 Apr 2003 10:35:12 +0800 (WST) +Message-ID: <077201c2fe40$ab420d70$6500a8c0@fhp.internal> +From: "Christopher Kings-Lynne" +To: , , + +References: +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Wed, 9 Apr 2003 10:35:22 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: base64 +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-scanner: scanned by Inflex 0.1.5c - (http://www.inflex.co.za/) +X-Spam-Status: No, hits=-11.1 required=5.0 + tests=BASE64_ENC_TEXT,BAYES_20,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/81 +X-Sequence-Number: 1587 + +SGkgRGVuaXMsDQoNCj4gVGhlIGtpbmQgb2YgcmVxdWVzdHMgdGhhdCBJIGFt +IHJlYWxseSBpbnRlcmVzdGVkIGluIGFyZToNCj4gc2VsZWN0IGNvdW50KCop +IGZyb20gdGFibGUgd2hlcmUgdGFibGUuY29sdW1uIGxpa2UgJ3BhdHRlcm4l +Jw0KPiBUaGVzZSBzZWVtcyB0byBnbyBtdWNoIG1hc3RlciBvbiBteXNxbCAo +d2hpY2ggSSBndWVzcyBpdCBub3QgYSBNVkNDIGRhdGFiYXNlPyBvciB3YXNu +J3QgDQo+IHRoZSBJbm5vYmFzZSBzdXBwb3NlZCB0byBtYWtlIGl0IHNvPyks +IHRoYW4gb24gcG9zdGdyZXNxbC4NCg0KQSBmZXcgdGhpbmdzLg0KDQoqIE1W +Q0MgaW4gUG9zdGdyZVNRTCBhbGxvd3MgdXMgdG8gYmUgd2F5IGZhc3RlciB0 +aGFuIE15U1FMIHdoZW4geW91IGhhdmUgaGVhcHMgb2YgY29uY3VycmVudCBy +ZWFkZXJzIGFuZCB3cml0ZXJzLiAgVGhlIHRyYWRlb2ZmIGlzIHRoYXQgY291 +bnQoKikgaXMgc2xvdyBzaW5jZSBQb3N0Z3JlU1FMIG5lZWRzIHRvIGNoZWNr +IHRoYXQgZWFjaCB0dXBsZSBpcyBhY3R1YWxseSB2aXNpYmxlIHRvIHlvdXIg +cXVlcnkgKGVnLiB5b3Ugc3RhcnQgYSB0cmFuc2FjdGlvbiwgc29tb25lIGVs +c2UgaW5zZXJ0cyBhIHJvdywgeW91IGRvIGEgY291bnQoKikgLSBzaG91bGQg +dGhlIHJlc3VsdCBpbmNsdWRlIHRoYXQgbmV3IHJvdyBvciBub3Q/ICBBbnN3 +ZXI6IG5vLikNCg0KKiBKdXN0IGF2b2lkIGRvaW5nIGNvdW50KCopIG92ZXIg +dGhlIGVudGlyZSB0YWJsZSB3aXRoIG5vIHdoZXJlIGNsYXVzZSEhISBJdCdz +IGFzIGVhc3kgYXMgdGhhdA0KDQoqIFRoZSBMSUtFICdwYXR0ZXJuJScgaXMg +aW5kZXhhYmxlIGluIFBvc3RncmVzcWwuICBZb3Ugd2lsbCBuZWVkIHRvIGNy +ZWF0ZSBhIG5vcm1hbCBidHJlZSBpbmRleCBvdmVyIHRhYmxlLmNvbHVtbi4g +IFNvIGxvbmcgYXMgdGhlIGluZGV4IGlzIHJldHVybmluZyBhIHNtYWxsIHBv +cnRpb24gb2YgdGhlIHRhYmxlIChlZy4gc2F5IG9ubHkgNS0xMCUgb2YgdGhl +IGZpZWxkcyBiZWdpbiB3aXRoIHBhdHRlcm4pLCB0aGVuIHRoZSBpbmRleCB3 +aWxsIGJlIHVzZWQgYW5kIGl0IHdpbGwgYmUgZmFzdC4NCg0KKiBJZiB5b3Ug +d2FudCByZWFsbHkgZmFzdCBmdWxsIHRleHQgaW5kZXhpbmcsIGNoZWNrIG91 +dCBjb250cmliL3RzZWFyY2ggLSBpdCdzIHJlYWxseSwgcmVhbGx5LCByZWFs +bHkgZmFzdC4NCg0KQ2hyaXMNCg== + +From pgsql-performance-owner@postgresql.org Tue Apr 8 23:18:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2702C4758E6 + for ; + Tue, 8 Apr 2003 23:18:47 -0400 (EDT) +Received: from svana.org (svana.org [203.20.62.76]) + by postgresql.org (Postfix) with ESMTP id 05C06474E42 + for ; + Tue, 8 Apr 2003 23:18:46 -0400 (EDT) +Received: from kleptog by svana.org with local (Exim 3.35 #1 (Debian)) + id 19366h-0006mT-00; Wed, 09 Apr 2003 13:18:39 +1000 +Date: Wed, 9 Apr 2003 13:18:39 +1000 +From: Martijn van Oosterhout +To: "Denis @ Next2Me" +Cc: pgsql-performance@postgresql.org +Subject: Re: [GENERAL] Yet Another (Simple) Case of Index not used +Message-ID: <20030409031839.GE15928@svana.org> +Reply-To: Martijn van Oosterhout +References: <20030408234623.GD15928@svana.org> + +Mime-Version: 1.0 +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; boundary="3XA6nns4nE4KvaS/" +Content-Disposition: inline +In-Reply-To: +User-Agent: Mutt/1.3.28i +X-PGP-Key-ID: Length=1024; ID=0x0DC67BE6 +X-PGP-Key-Fingerprint: 295F A899 A81A 156D B522 48A7 6394 F08A 0DC6 7BE6 +X-PGP-Key-URL: +X-Spam-Status: No, hits=-45.1 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/82 +X-Sequence-Number: 1588 + +--3XA6nns4nE4KvaS/ +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +Content-Transfer-Encoding: quoted-printable + +On Tue, Apr 08, 2003 at 05:10:01PM -0700, Denis @ Next2Me wrote: +> Interesting generic response. In other words, "it all depends". +> Well, a de facto observation is: "In my case, it's always much slower wit= +h, say, mysql". + +Curious, is mysql still so fast when you have transactions enabled? How does +it deal with the following: + +begin; +delete from bigtable; +select count(*) from bigtable; -- Should return 0 +abort; +select count(*) from bigtable; -- Should give original size + +> Understand me, I don't mean to be starting a performance comparaison mysql +> vs postgresql, which is probably an old subject, I am just looking for a +> solution to solve this type of performance issues, ie the generic cases: +> select count(*) from addresses where address is like 'pattern%'; +> Which are very fast on mysql, and very slow on postgresql. + +Ah, but that may be caused by something else altogether. LIKE is only +indexable in the C locale so if you have en_US as your locale, your LIKE +won't be indexable. See the discussion threads on this mailing list in the = +past. + +> Understood, it will always depend on some parameters, but the real +> question is: how much control does one have over those parameters, and how +> does one tweak them to reach optimal performance? + +Hmm, it depends. One person put it that mysql goes for performance first, +then correctness, whereas postgresql goes for correctness first, then +performance. + +Maybe fti (full text indexing) would work better? + +--=20 +Martijn van Oosterhout http://svana.org/kleptog/ +> "the West won the world not by the superiority of its ideas or values or +> religion but rather by its superiority in applying organized violence. +> Westerners often forget this fact, non-Westerners never do." +> - Samuel P. Huntington + +--3XA6nns4nE4KvaS/ +Content-Type: application/pgp-signature +Content-Disposition: inline + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.6 (GNU/Linux) +Comment: For info see http://www.gnupg.org + +iD8DBQE+k5EPY5Twig3Ge+YRAiovAKCHfX0JXOzbUVfEIrnixz+XwZ1wYQCfWW39 +OTdtMALGGZa5+0KFOpRhFjA= +=s8Ph +-----END PGP SIGNATURE----- + +--3XA6nns4nE4KvaS/-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 8 23:38:57 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 614254758E6 + for ; + Tue, 8 Apr 2003 23:38:56 -0400 (EDT) +Received: from ms-smtp-01.tampabay.rr.com (ms-smtp-01.tampabay.rr.com + [65.32.1.43]) by postgresql.org (Postfix) with ESMTP id 9447E474E42 + for ; + Tue, 8 Apr 2003 23:38:55 -0400 (EDT) +Received: from mattspc (169-52.34-65.tampabay.rr.com [65.34.52.169]) + by ms-smtp-01.tampabay.rr.com (8.12.5/8.12.5) with ESMTP id + h393coVn028692 for ; + Tue, 8 Apr 2003 23:38:50 -0400 (EDT) +From: "Matthew Nuzum" +To: "Pgsql-Performance" +Subject: choosing the right platform +Date: Tue, 8 Apr 2003 23:38:44 -0400 +Organization: Bearfruit.org +Message-ID: <003101c2fe49$86a9fc30$6900a8c0@mattspc> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4510 +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-1.6 required=5.0 + tests=BAYES_30 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/83 +X-Sequence-Number: 1589 + +Hello all, + +I've been the lead developer of a successful (so-far) web application. +Currently we run the database and the web application on the same server, +but it will soon be necessary to split them and add some more web servers. + +I'm not counting on using replication any time soon, so I want to choose the +hardware platform that will meet my needs for some time. Maybe you can give +some suggestions... + +My application is written in PHP and relies on the apache web server. We +use persistent db connections, so it appears (correct me if I'm wrong) that +every apache child process gets one connection to the database. If my +MaxClients is 150, each web server will be able to make up to 150 db +connections. I'd like to play with that number a little bit once I get the +webserver off of the db server. I feel that I could handle a greater number +of Clients, so let us say that I have up to 200 connections per server. + +I'd like to have room to grow, so let's also say that I go to 20 web servers +for a total of 4000 connections. (I'd probably like to go even higher, so +consider this our starting point) + +With a couple dozen active accounts and a lot of test data, my current +database is equiv to about 100 active accounts. Its current disk space +consumption is: +data # du --max-depth=3D2 +3656 ./base/1 +3656 ./base/16975 +4292 ./base/95378 +177824 ./base/200371 +189432 ./base +144 ./global +82024 ./pg_xlog +2192 ./pg_clog +273836 . + +This is not optimized and there is a lot of old data, but to be safe, maybe +we should assume that each account uses 4 MB of disk space in the db, +counting indexes, tables and etc. I'd like to scale to 15,000 - 25,000 +accounts, but I doubt that will be feasible at my budget level. (Also, +there is a lot of optimizing to do, so it won't surprise me if this 4MB +number is more like 2MB or even less) + +I'm not as concerned with disk subsystem or layout at the moment. I've seen +a lot of good documentation (especially from Bruce Momjian, thanks!) on this +subject. I'm mostly concerned with choosing the platform that's going to +allow the scalability I need. + +Currently I'm most experienced in Linux, especially RedHat. I'm "certified" +on SCO Openserver (5.x) and I've played with Irix, OSF/1 (I don't think it's +called that anymore), Free BSD (3.x) and Solaris (2.x). I'm most +comfortable with Linux, but I'm willing to use a different platform if it +will be beneficial. I've heard that Solaris on the Sparc platform is +capable of addressing larger amounts of RAM than Linux on Intel does. I +don't know if that's true or if that has bearing, but I'd like to hear your +opinions. + +My budget is going to be between (US) $5,000 and $10,000 and I'd like to +stay under $7,000. I'm a major bargain hunter, so I shop e-bay a lot and +here are some samplings that I think may be relevant for discussion: + +SUN (I'm not an expert in this, advice is requested) +---------------------------------------------------- +SUN ENTERPRISE 4500 8x400 Mhz 4MB Cache CPUs 8GB RAM no hard drives ~$6,000 +Sun E3500 - 8 x 336MHz 4MB Cache CPUs 4GB RAM 8 x 9.1GB FC disks ~$600.00 +Any other suggestions? + +INTEL (I'm much more familiar with this area) +---------------------------------------------------- +Compaq DL580 4x700 MHz 2MB Cache CPUs 4GB RAM (16GB Max) HW Raid w/ 64MB +Cache ~$6000 +IBM Netfinity 7100 4x500 MHz 1MB Cache CPUs up to (16GB Max) HW Raid +Dell PowerEdge 8450 8x550 2M Cache CPUS 4GB (32GB Max) HS RAID w/ 16MB Cache +~$4,500 +Any other suggestions? + +Any other hardware platforms I should consider? + +Finally, and I know this sounds silly, but I don't have my own data center, +so size is something I need to take into consideration. I pay for data +center space by the physical size of my servers. My priorities are +Performance, Reasonable amount of scalability (as outlined above) and +finally physical size. + +Thanks for taking the time to read this and for any assistance you can give, + +Matthew Nuzum +www.bearfruit.org + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 01:57:02 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2EE074758E6 + for ; + Wed, 9 Apr 2003 01:57:01 -0400 (EDT) +Received: from localhost.localdomain + (adsl-216-103-208-155.dsl.snfc21.pacbell.net [216.103.208.155]) + by postgresql.org (Postfix) with ESMTP id 569A4474E42 + for ; + Wed, 9 Apr 2003 01:57:00 -0400 (EDT) +Received: from flipper5 (flipper5.next2me.com [192.168.0.3]) + by localhost.localdomain (8.12.8/8.12.8) with SMTP id h395wMgL002290; + Tue, 8 Apr 2003 22:58:22 -0700 +Reply-To: +From: "Denis @ Next2Me" +To: "Martijn van Oosterhout" , + "Stephan Szabo" , + "Denis @ Next2Me" +Cc: +Subject: Re: [GENERAL] Yet Another (Simple) Case of Index not used +Date: Tue, 8 Apr 2003 22:54:46 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <20030409031839.GE15928@svana.org> +X-Spam-Status: No, hits=-14.7 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/84 +X-Sequence-Number: 1590 + +Stephan, Martijn, +good call, that was it: the C locale. + +I had used all the default settings when installing/creating the database, +and apparently it used my default locale (en_US). +I recreated (initdb) the database with --no-locale, and recreated the database, +and sure enough, the query: +select count(*) from table where table.column like 'fol%' +was a zillion (well almost) time faster than it used to be, +and on pair with mysql's performance. +And as expected, the EXPLAIN on that query does show indeed +the use of the index I had created on the table. + +Sweet, I can now nuke mysql out of my system. + +Folks, thank you all for the help and other suggestions. + +Denis Amselem +Next2Me Inc. + + + + +Stephan said: + > If it doesn't use the index (ie, it's still using a sequential scan) + > after the enable_seqscan=off it's likely that you didn't initdb in "C" + > locale in which case like won't use indexes currently (you can see the + > archives for long description, but the short one is that some of the + > locale rules can cause problems with using the index). + +Martijn said: + + > Ah, but that may be caused by something else altogether. LIKE is only + > indexable in the C locale so if you have en_US as your locale, your LIKE + > won't be indexable. See the discussion threads on this mailing list in the past. + > + > + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 11:43:17 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BE4384762F6 + for ; + Wed, 9 Apr 2003 11:43:13 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 93D904762D7 + for ; + Wed, 9 Apr 2003 11:43:09 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h39Fga208429 + for ; Wed, 9 Apr 2003 21:12:36 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h39Fgaa08424 + for ; Wed, 9 Apr 2003 21:12:36 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: [OT][Announce] Availability of OAS Server pakcages +Date: Wed, 9 Apr 2003 21:12:56 +0530 +User-Agent: KMail/1.5 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304092112.56916.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-5.8 required=5.0 tests=BAYES_10,USER_AGENT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/85 +X-Sequence-Number: 1591 + +Hello all, + +This is to announce couple of things regarding OAS Server. + +1. Mailing list for OAS Server is up now. It is available at +https://lists.sourceforge.net/lists/listinfo/oasserver-general. + +So I wouldn't be bothering you guys next time like this..:-) + +2. First packaging release of OAS Server is made available. So in case, you do +not want to use CVS, try the source tarballs. + +The project website is http://oasserver.sourceforge.net + +Regards + Shridhar + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 12:11:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 908BE475FEE + for ; + Wed, 9 Apr 2003 12:11:07 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 9CA29475ECE + for ; + Wed, 9 Apr 2003 12:10:57 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2952996; Wed, 09 Apr 2003 09:10:56 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Kevin Brown , + pgsql-performance@postgresql.org +Subject: Re: ext3 filesystem / linux 7.3 +Date: Wed, 9 Apr 2003 09:10:29 -0700 +User-Agent: KMail/1.4.3 +References: <231C6A82-65C3-11D7-8D88-0003939CC61E@trilug.org> + <200304030943.06406.josh@agliodbs.com> + <20030408232247.GH1847@filer> +In-Reply-To: <20030408232247.GH1847@filer> +MIME-Version: 1.0 +Message-Id: <200304090910.29057.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/86 +X-Sequence-Number: 1592 + +Kevin, + +> So perhaps the first step in this is to write something that will show +> what the distribution pattern for data in a table is? With that +> information, we *could* randomly generate data that would conform to +> the statistical patterns seen in the real world. + +Sure. But I think it'll be *much* easier just to use portions of the FCC= +=20 +database. You want to start working on converting it to PostgreSQL? + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 12:19:17 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 34D7B475A8D + for ; + Wed, 9 Apr 2003 12:19:14 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 6C186475458 + for ; + Wed, 9 Apr 2003 12:19:13 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2953011; Wed, 09 Apr 2003 09:19:13 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: , +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Wed, 9 Apr 2003 09:18:45 -0700 +User-Agent: KMail/1.4.3 +References: +In-Reply-To: +MIME-Version: 1.0 +Message-Id: <200304090918.45275.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/87 +X-Sequence-Number: 1593 + +Denis, + +> Are you saying the 7.4 'group by' trick would be faster than the simple +> select count(*)? That seems hard to believe, being that the request now h= +as +> to fetch / sort the data. I must be missing something. + +No, I'm saying that the 7.4 hash-aggregate is faster than the same query wa= +s=20 +under 7.2 or 7.3. Much faster. But it does little to speed up a raw=20 +count(*). + +> The kind of requests that I am really interested in are: +> select count(*) from table where table.column like 'pattern%' + +Hash-aggregates may, in fact, help with this. Care to try downloading the= +=20 +the source from CVS? + +> These seems to go much master on mysql (which I guess it not a MVCC +> database? or wasn't the Innobase supposed to make it so?), + +They did incorporate a lot of MVCC logic into InnoDB tables, yes. Which me= +ans=20 +that if SELECT count(*) on an InnoDB table is just as fast as a MyISAM tabl= +e,=20 +then it is not accurate. This would be in keeping with MySQL's design=20 +philosophy, which values performance and simplicity over accuracy and=20 +precision -- the opposite of our philosophy. + +> So, in the meantime, I've decided to split up my data into two sets, +> the static big tables which are handled by mysql, and the rest of it +> handled by postgresql.... + +Hey, if it works for you, it's probably easier than dealing with the=20 +PostgreSQL workarounds to this performance issue. I'll ask you to give=20 +PostgreSQL a try for those tables again when 7.4 comes out. + +> ps: apologies for the cross-posting. + +De nada. The Performance list is the right place for this sort of questio= +n=20 +in the future. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 12:28:31 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EF124476353 + for ; + Wed, 9 Apr 2003 12:28:30 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 2119F47634E + for ; + Wed, 9 Apr 2003 12:28:30 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2953027; Wed, 09 Apr 2003 09:28:29 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Matthew Nuzum" , + "Pgsql-Performance" +Subject: Re: choosing the right platform +Date: Wed, 9 Apr 2003 09:28:01 -0700 +User-Agent: KMail/1.4.3 +References: <003101c2fe49$86a9fc30$6900a8c0@mattspc> +In-Reply-To: <003101c2fe49$86a9fc30$6900a8c0@mattspc> +MIME-Version: 1.0 +Message-Id: <200304090928.01767.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/88 +X-Sequence-Number: 1594 + +Matthew, + +> Currently I'm most experienced in Linux, especially RedHat. I'm +> "certified" on SCO Openserver (5.x) and I've played with Irix, OSF/1 (I +> don't think it's called that anymore), Free BSD (3.x) and Solaris (2.x).= +=20 +> I'm most +> comfortable with Linux, but I'm willing to use a different platform if it +> will be beneficial. I've heard that Solaris on the Sparc platform is +> capable of addressing larger amounts of RAM than Linux on Intel does. I +> don't know if that's true or if that has bearing, but I'd like to hear yo= +ur +> opinions. + +Please browse through the list archives. We have numerous posts on the=20 +platform subject. In fact, several of us are trying to put together a=20 +PostgreSQL performance test package to answer this question difinitively=20 +rather than anecdotally. + +Anecdotal responses are: + +Solaris is *bad* for PostgreSQL, due to a high per-process overhead.=20=20 +Universal opinion on this list has been that Solaris is optimized for=20 +multi-threaded applications, not multi-process applications, and postgres i= +s=20 +the latter. + +*BSD has a *lot* of fans on the PGSQL lists, many of whom claim significant= +ly=20 +better performance than Linux, mostly due to better filesystem I/O. + +Linux is used heavily by a lot of PostgreSQL users. I have yet to see anyo= +ne=20 +provide actual Linux vs. BSD statistics, though ... something we hope to do. + +Nobody has come forward and reported on PostgreSQL on SCO Unix. + +Irix is widely regarded as a "dead" platform, though PostgreSQL does run on= + it=20 +... + +Good luck, and keep watching this space! + + + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 12:57:11 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D3E26476302 + for ; + Wed, 9 Apr 2003 12:57:08 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id A6628476262 + for ; + Wed, 9 Apr 2003 12:57:07 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h39GtVYQ025856; + Wed, 9 Apr 2003 10:55:31 -0600 (MDT) +Date: Wed, 9 Apr 2003 10:51:34 -0600 (MDT) +From: "scott.marlowe" +To: Matthew Nuzum +Cc: Pgsql-Performance +Subject: Re: choosing the right platform +In-Reply-To: <003101c2fe49$86a9fc30$6900a8c0@mattspc> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-28.2 required=5.0 + tests=BAYES_20,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/89 +X-Sequence-Number: 1595 + +I would say up front that both Linux and BSD are probably your two best +choices. If you're familiar with one more than the other, that +familiarity may be more important than the underlying differences in the +two OSes, as they are both good platforms to run postgresql on top of. + +Secondly, look carefully at using persistant connections in large numbers. + +While persistant connections DO represent a big savings in connect time, +the savings are lost in the noise of many PHP applications. + +i.e. my dual PIII swiss army knife server can initiate single persistant +connections at 1,000,000 a second (reusing the old ones of course). +non-persistant connects happen at 1,000 times a second. Most of my +scripts run in 1/10th of a second or so, so the 1/1000th used to connect +is noise to me. + +If you are going to use persistant connections, it might work better to +let apache have only 20 or 40 children, which will force the apache +children to "round robin" serve the requests coming in. + +This will usually work fine, since keeping the number of apache children +down keeps the number of postgresql backends down, which keeps the system +faster in terms of response time. Turn keep alive down to something short +like 10 seconds, or just turn it off, as keep alive doesn't really save +all that much time in apache. + +Note that machine testing with 100 simo connections doesn't translate +directly to 100 users. Generally, x simos usually represents about 10 to +20 x users, since users don't click buttons all that fast. so an apache +configured by 40 max children should handle 100 to 200 users with no +problem. + +On Tue, 8 Apr 2003, Matthew Nuzum wrote: + +> Hello all, +> +> I've been the lead developer of a successful (so-far) web application. +> Currently we run the database and the web application on the same server, +> but it will soon be necessary to split them and add some more web servers. +> +> I'm not counting on using replication any time soon, so I want to choose the +> hardware platform that will meet my needs for some time. Maybe you can give +> some suggestions... +> +> My application is written in PHP and relies on the apache web server. We +> use persistent db connections, so it appears (correct me if I'm wrong) that +> every apache child process gets one connection to the database. If my +> MaxClients is 150, each web server will be able to make up to 150 db +> connections. I'd like to play with that number a little bit once I get the +> webserver off of the db server. I feel that I could handle a greater number +> of Clients, so let us say that I have up to 200 connections per server. +> +> I'd like to have room to grow, so let's also say that I go to 20 web servers +> for a total of 4000 connections. (I'd probably like to go even higher, so +> consider this our starting point) +> +> With a couple dozen active accounts and a lot of test data, my current +> database is equiv to about 100 active accounts. Its current disk space +> consumption is: +> data # du --max-depth=2 +> 3656 ./base/1 +> 3656 ./base/16975 +> 4292 ./base/95378 +> 177824 ./base/200371 +> 189432 ./base +> 144 ./global +> 82024 ./pg_xlog +> 2192 ./pg_clog +> 273836 . +> +> This is not optimized and there is a lot of old data, but to be safe, maybe +> we should assume that each account uses 4 MB of disk space in the db, +> counting indexes, tables and etc. I'd like to scale to 15,000 - 25,000 +> accounts, but I doubt that will be feasible at my budget level. (Also, +> there is a lot of optimizing to do, so it won't surprise me if this 4MB +> number is more like 2MB or even less) +> +> I'm not as concerned with disk subsystem or layout at the moment. I've seen +> a lot of good documentation (especially from Bruce Momjian, thanks!) on this +> subject. I'm mostly concerned with choosing the platform that's going to +> allow the scalability I need. +> +> Currently I'm most experienced in Linux, especially RedHat. I'm "certified" +> on SCO Openserver (5.x) and I've played with Irix, OSF/1 (I don't think it's +> called that anymore), Free BSD (3.x) and Solaris (2.x). I'm most +> comfortable with Linux, but I'm willing to use a different platform if it +> will be beneficial. I've heard that Solaris on the Sparc platform is +> capable of addressing larger amounts of RAM than Linux on Intel does. I +> don't know if that's true or if that has bearing, but I'd like to hear your +> opinions. +> +> My budget is going to be between (US) $5,000 and $10,000 and I'd like to +> stay under $7,000. I'm a major bargain hunter, so I shop e-bay a lot and +> here are some samplings that I think may be relevant for discussion: +> +> SUN (I'm not an expert in this, advice is requested) +> ---------------------------------------------------- +> SUN ENTERPRISE 4500 8x400 Mhz 4MB Cache CPUs 8GB RAM no hard drives ~$6,000 +> Sun E3500 - 8 x 336MHz 4MB Cache CPUs 4GB RAM 8 x 9.1GB FC disks ~$600.00 +> Any other suggestions? +> +> INTEL (I'm much more familiar with this area) +> ---------------------------------------------------- +> Compaq DL580 4x700 MHz 2MB Cache CPUs 4GB RAM (16GB Max) HW Raid w/ 64MB +> Cache ~$6000 +> IBM Netfinity 7100 4x500 MHz 1MB Cache CPUs up to (16GB Max) HW Raid +> Dell PowerEdge 8450 8x550 2M Cache CPUS 4GB (32GB Max) HS RAID w/ 16MB Cache +> ~$4,500 +> Any other suggestions? +> +> Any other hardware platforms I should consider? +> +> Finally, and I know this sounds silly, but I don't have my own data center, +> so size is something I need to take into consideration. I pay for data +> center space by the physical size of my servers. My priorities are +> Performance, Reasonable amount of scalability (as outlined above) and +> finally physical size. +> +> Thanks for taking the time to read this and for any assistance you can give, +> +> Matthew Nuzum +> www.bearfruit.org +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org +> + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 13:14:00 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 69E43476342 + for ; + Wed, 9 Apr 2003 13:13:57 -0400 (EDT) +Received: from ms-smtp-03.tampabay.rr.com (ms-smtp-03.tampabay.rr.com + [65.32.1.41]) by postgresql.org (Postfix) with ESMTP id 90C3C476340 + for ; + Wed, 9 Apr 2003 13:13:56 -0400 (EDT) +Received: from mattspc (169-52.34-65.tampabay.rr.com [65.34.52.169]) + by ms-smtp-03.tampabay.rr.com (8.12.5/8.12.5) with ESMTP id + h39HDpbm010125; Wed, 9 Apr 2003 13:13:54 -0400 (EDT) +From: "Matthew Nuzum" +To: "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: choosing the right platform +Date: Wed, 9 Apr 2003 13:13:46 -0400 +Organization: Bearfruit.org +Message-ID: <00a001c2febb$631141d0$6900a8c0@mattspc> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4510 +Importance: Normal +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +In-Reply-To: <200304090928.01767.josh@agliodbs.com> +X-Spam-Status: No, hits=-9.5 required=5.0 + tests=BAYES_20,IN_REP_TO,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/90 +X-Sequence-Number: 1596 + +> Anecdotal responses are: +>=20 +> Solaris is *bad* for PostgreSQL, due to a high per-process overhead. +> Universal opinion on this list has been that Solaris is optimized for +> multi-threaded applications, not multi-process applications, and postgres +> is +> the latter. +>=20 +> *BSD has a *lot* of fans on the PGSQL lists, many of whom claim +> significantly +> better performance than Linux, mostly due to better filesystem I/O. +>=20 +> Linux is used heavily by a lot of PostgreSQL users. I have yet to see +> anyone +> provide actual Linux vs. BSD statistics, though ... something we hope to +> do. +... +> -- +> Josh Berkus +> Aglio Database Solutions +> San Francisco + +Thanks for the reply. Three things come to mind: + +About the list archives... + +I read through the entire archive at +http://archives.postgresql.org/pgsql-performance/ and didn't see much talk +on the subject. It only goes back 8 months though, so I don't know if there +is another archive that is more comprehensive... + +Also, + +I'm glad to hear your comments about Solaris, I'm really most comfortable +with Linux and I think I can pick up BSD pretty easily. + +About the Intel platform though, + +It's only been pretty recently (relatively speaking) that servers based on +IA32 architecture have had support for greater than 2GB of RAM. I've heard +talk about problems with applications that require more than 2GB. I do +believe that my tables will become larger than this, and the way I +understand it, sort mem works best when the tables can be loaded completely +in RAM. + +I don't suspect that individual tables will be 2GB, but that the size of all +tables combined will be. If there is a limitation on the largest chunk of +RAM allocated to a program, will I have problems? + +Finally, can someone suggest a *BSD to evaluate? FreeBSD 4.8? 5.0? Is Apple +a good choice? (I've heard it's based on BSD Unix) + +Thanks, + +-- +Matthew Nuzum +www.bearfruit.org +cobalt@bearfruit.org +=20 + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 13:20:31 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 17ED9476340 + for ; + Wed, 9 Apr 2003 13:20:30 -0400 (EDT) +Received: from l2.socialecology.com (unknown [4.42.179.131]) + by postgresql.org (Postfix) with ESMTP id DA03547633A + for ; + Wed, 9 Apr 2003 13:20:27 -0400 (EDT) +Received: from 4.42.179.151 (broccoli.socialecology.com [4.42.179.151]) + by l2.socialecology.com (Postfix) with SMTP + id 074D2581998; Wed, 9 Apr 2003 10:20:25 -0700 (PDT) +X-Mailer: UserLand Frontier 9.1b2 (Macintosh OS) (mailServer v1.1..144) +Mime-Version: 1.0 +Message-Id: <67638702.1162238874@[4.42.179.151]> +X-authenticated-sender: erics +In-reply-to: <00a001c2febb$631141d0$6900a8c0@mattspc> +Date: Wed, 09 Apr 2003 10:20:22 -0700 +To: Matthew Nuzum , 'Josh Berkus' , + 'Pgsql-Performance' +From: eric soroos +Subject: Re: choosing the right platform +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-6.3 required=5.0 tests=BAYES_20,IN_REP_TO + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/91 +X-Sequence-Number: 1597 + + +> Finally, can someone suggest a *BSD to evaluate? FreeBSD 4.8? 5.0? Is Apple +> a good choice? (I've heard it's based on BSD Unix) + +I wouldn't recommend OSX for deployment if you're worried about performance. The hardware availiable and the settings to take advantage of it just aren't there yet, compared to the more established FreeBSD and Linux offerings. + +Development on a tibook is another matter, I'd recommend it to anyone with an attraction to shiny things that do real work. + +eric + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 14:01:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AC240474E44 + for ; + Wed, 9 Apr 2003 14:01:13 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 09D4A474E42 + for ; + Wed, 9 Apr 2003 14:01:11 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h39HxrYQ001563; + Wed, 9 Apr 2003 11:59:53 -0600 (MDT) +Date: Wed, 9 Apr 2003 11:55:56 -0600 (MDT) +From: "scott.marlowe" +To: Matthew Nuzum +Cc: "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: choosing the right platform +In-Reply-To: <00a001c2febb$631141d0$6900a8c0@mattspc> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/92 +X-Sequence-Number: 1598 + +On Wed, 9 Apr 2003, Matthew Nuzum wrote: + +> I'm glad to hear your comments about Solaris, I'm really most comfortable +> with Linux and I think I can pick up BSD pretty easily. +> +> About the Intel platform though, +> +> It's only been pretty recently (relatively speaking) that servers based on +> IA32 architecture have had support for greater than 2GB of RAM. I've heard +> talk about problems with applications that require more than 2GB. I do +> believe that my tables will become larger than this, and the way I +> understand it, sort mem works best when the tables can be loaded completely +> in RAM. +> +> I don't suspect that individual tables will be 2GB, but that the size of all +> tables combined will be. If there is a limitation on the largest chunk of +> RAM allocated to a program, will I have problems? + +A couple more suggestions. One is to never allocate more than 50% of your +memory to a database's shared buffers, i.e. let the OS buffer the disks en +masse, while the database should have a smaller buffer for the most recent +accesses. This is because kernel caching is usually faster and more +efficient than the database doing it, and this becomes more an issue with +large chunks of memory, which both Linux and BSD are quite good at +caching, and postgresql, not so good. + +The other is to look at Linux or BSD on 64 bit hardware (Sparc, IBM +Zseries mainframes, SGI Altix, etc...) where the one thing that's worth +being on the bleeding edge for is databases and their memory hungry ways. +:-) + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 14:04:00 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0B818474E44 + for ; + Wed, 9 Apr 2003 14:04:00 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 655DB474E42 + for ; + Wed, 9 Apr 2003 14:03:59 -0400 (EDT) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2953260; Wed, 09 Apr 2003 11:03:53 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Matthew Nuzum" , + "'Pgsql-Performance'" +Subject: Re: choosing the right platform +Date: Wed, 9 Apr 2003 11:03:48 -0700 +User-Agent: KMail/1.4.3 +References: <00a001c2febb$631141d0$6900a8c0@mattspc> +In-Reply-To: <00a001c2febb$631141d0$6900a8c0@mattspc> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304091103.48151.josh@agliodbs.com> +X-Spam-Status: No, hits=-21.9 required=5.0 + tests=BAYES_10,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/93 +X-Sequence-Number: 1599 + +Matthew, + +> I read through the entire archive at +> http://archives.postgresql.org/pgsql-performance/ and didn't see much talk +> on the subject. It only goes back 8 months though, so I don't know if th= +ere +> is another archive that is more comprehensive... + +Really? There was a long-running Mac OS X vs. Solaris thread that touched = +on=20 +most major platforms, about 2-3 months ago. + +> I don't suspect that individual tables will be 2GB, but that the size of = +all +> tables combined will be. If there is a limitation on the largest chunk of +> RAM allocated to a program, will I have problems? + +No. Since PostgreSQL is a multi-process architecture, not a multi-threaded= +,=20 +you only need enough RAM per process to load the current largest query. + +Plus, in my experience, Disk I/O issues are vastly more important than RAM = +in=20 +database performance. You're better off spending money on really fast dis= +ks=20 +in Linux RAID or really good hardware RAID 1+0 .... + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 19:45:13 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 034F5475458 + for ; + Wed, 9 Apr 2003 19:45:00 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 9D6DC474E42 + for ; + Wed, 9 Apr 2003 19:44:58 -0400 (EDT) +Received: (qmail 57171 invoked by uid 1001); 9 Apr 2003 23:45:01 -0000 +Date: Wed, 9 Apr 2003 18:45:01 -0500 +From: "Jim C. Nasby" +To: Matthew Nuzum +Cc: 'Josh Berkus' , + 'Pgsql-Performance' +Subject: Re: choosing the right platform +Message-ID: <20030409184501.V31861@flake.decibel.org> +Reply-To: jim@nasby.net +References: <200304090928.01767.josh@agliodbs.com> + <00a001c2febb$631141d0$6900a8c0@mattspc> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <00a001c2febb$631141d0$6900a8c0@mattspc>; + from cobalt@bearfruit.org on Wed, Apr 09, 2003 at 01:13:46PM -0400 +X-Operating-System: FreeBSD 4.7-RELEASE-p3 i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-35.4 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/94 +X-Sequence-Number: 1600 + +On Wed, Apr 09, 2003 at 01:13:46PM -0400, Matthew Nuzum wrote: +> Finally, can someone suggest a *BSD to evaluate? FreeBSD 4.8? 5.0? Is Apple +> a good choice? (I've heard it's based on BSD Unix) + +FreeBSD has 3 different branches: + +-current: +This is bleeding edge. Definitely need to be careful with this one, and +it's not recommended for production. + +-stable: +This is still a 'live' branch that any FBSD coder can (generally) commit +to, but they are far more careful about breaking this branch. Not as +stable as a release branch, but it's probably suitable for production so +long as you're careful to test things. + +release branches: +Every time an official release is done (ie: 4.8), a branch is created. +The only code committed to these branches are security patches and fixes +for very serious bugs. These branches are extremely stable. + +5.0 is the first release after several years of development in -current. +It incorporates some major changes designed to allow the kernel to run +multi-threaded. However, unlike what usually happens, 5.0 is not +considered to be -stable yet. First, this is still very new code; +second, I believe there's some performance issues that are still being +addressed. The intention is that 5.1 will be the first -stable release +of the 5.x code. + +Because you're looking for something that's production ready, you +probably want 4.8 (cvs tag RELENG_4_8). However, if you don't plan to +hit production until late this year (when 5.1 should be out), you might +want to try 5.0. + +Far more info is available at http://www.freebsd.org/releng/index.html + +BTW, I've heard of many, many companies moving their Oracle installs +from Sun to RS/6000 because RS/6000's typically need 1/2 the processors +that Sun does for a given load. If you're going to look at big-iron, +RS/6000 is definitely worth a look if you see anything. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 19:47:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B6C07475458 + for ; + Wed, 9 Apr 2003 19:47:46 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 83F9F474E42 + for ; + Wed, 9 Apr 2003 19:47:41 -0400 (EDT) +Received: (qmail 57261 invoked by uid 1001); 9 Apr 2003 23:47:44 -0000 +Date: Wed, 9 Apr 2003 18:47:44 -0500 +From: "Jim C. Nasby" +To: "scott.marlowe" +Cc: Matthew Nuzum , 'Josh Berkus' , + 'Pgsql-Performance' +Subject: Re: choosing the right platform +Message-ID: <20030409184744.W31861@flake.decibel.org> +Reply-To: jim@nasby.net +References: <00a001c2febb$631141d0$6900a8c0@mattspc> + +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: ; + from scott.marlowe@ihs.com on Wed, Apr 09, 2003 at 11:55:56AM + -0600 +X-Operating-System: FreeBSD 4.7-RELEASE-p3 i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-39.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/95 +X-Sequence-Number: 1601 + +On Wed, Apr 09, 2003 at 11:55:56AM -0600, scott.marlowe wrote: +> A couple more suggestions. One is to never allocate more than 50% of your +> memory to a database's shared buffers, i.e. let the OS buffer the disks en +> masse, while the database should have a smaller buffer for the most recent +> accesses. This is because kernel caching is usually faster and more +> efficient than the database doing it, and this becomes more an issue with +> large chunks of memory, which both Linux and BSD are quite good at +> caching, and postgresql, not so good. + +That seems odd... shouldn't pgsql be able to cache information better +since it would be cached in whatever format is best for it, rather than +the raw page format (or maybe that is the best format). There's also the +issue of having to go through more layers of software if you're relying +on the OS caching. All the tuning info I've seen for every other +database I've worked with specifically recommends giving the database as +much memory as you possibly can, the theory being that it will do a much +better job of caching than the OS will. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 19:58:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9268C475458 + for ; + Wed, 9 Apr 2003 19:58:42 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 6D13D474E42 + for ; + Wed, 9 Apr 2003 19:58:40 -0400 (EDT) +Received: (qmail 57465 invoked by uid 1001); 9 Apr 2003 23:58:43 -0000 +Date: Wed, 9 Apr 2003 18:58:43 -0500 +From: "Jim C. Nasby" +To: "scott.marlowe" +Cc: Matthew Nuzum , + Pgsql-Performance +Subject: Re: choosing the right platform +Message-ID: <20030409185843.X31861@flake.decibel.org> +Reply-To: jim@nasby.net +References: <003101c2fe49$86a9fc30$6900a8c0@mattspc> + +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: ; + from scott.marlowe@ihs.com on Wed, Apr 09, 2003 at 10:51:34AM + -0600 +X-Operating-System: FreeBSD 4.7-RELEASE-p3 i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/96 +X-Sequence-Number: 1602 + +On Wed, Apr 09, 2003 at 10:51:34AM -0600, scott.marlowe wrote: +> Secondly, look carefully at using persistant connections in large numbers. +> +> While persistant connections DO represent a big savings in connect time, +> the savings are lost in the noise of many PHP applications. +> +> i.e. my dual PIII swiss army knife server can initiate single persistant +> connections at 1,000,000 a second (reusing the old ones of course). +> non-persistant connects happen at 1,000 times a second. Most of my +> scripts run in 1/10th of a second or so, so the 1/1000th used to connect +> is noise to me. + +My $0.02 from my experience with Sybase and DB2: +It's not the connection *time* that's an issue, it's the amount of +resources (mostly memory) used by each database connection. Each db2 +connection to a database uses 4-8 meg of memory; on my pgsql system, +each connection appears to be using about 4M. This is the resident set, +which I believe indicates memory that basically can't be shared. All +this memory is memory that can't be used for buffering/caching; on a +system with a hundred connections, it can really start to add up. + +If your PHP is written in such a way that it does all the database work +in one section of code, and only holds a connection to the database in +that one section, then you can potentially have a lot of apache +processes for each database connection. + +Of course, all this holds true wether you're using pooling or not. How +much pooling will help depends on how expensive it is for the *database* +to handle each new connection request, and how your code is written. +Since it's often not possible to put all you database code in one place +like I mentioned above, an alternative is to connect right before you do +an operation, and disconnect as soon as you're done. This doesn't add +much (if any) expense if you're using pooling, but it's a very different +story if you're not using pooling. + +> If you are going to use persistant connections, it might work better to +> let apache have only 20 or 40 children, which will force the apache +> children to "round robin" serve the requests coming in. +> +> This will usually work fine, since keeping the number of apache children +> down keeps the number of postgresql backends down, which keeps the system +> faster in terms of response time. Turn keep alive down to something short +> like 10 seconds, or just turn it off, as keep alive doesn't really save +> all that much time in apache. + +Very important advice. Generally, once you push a database past a +certain point, your performance degrades severely as the database +thrashes about trying to answer all the pending queries. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 20:15:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 98A8F475458 + for ; + Wed, 9 Apr 2003 20:15:42 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 2D6A7474E42 + for ; + Wed, 9 Apr 2003 20:15:41 -0400 (EDT) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2954009 for pgsql-performance@postgresql.org; + Wed, 09 Apr 2003 17:15:24 -0700 +Content-Type: text/plain; + charset="us-ascii" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Pgsql-Performance +Subject: Help analyzing 7.2.4 EXPLAIN +Date: Wed, 9 Apr 2003 17:15:19 -0700 +User-Agent: KMail/1.4.3 +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304091715.19565.josh@agliodbs.com> +X-Spam-Status: No, hits=-12.2 required=5.0 tests=BAYES_10,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/97 +X-Sequence-Number: 1603 + +Folks, + +What follows is a 7.2.4 EXPLAIN ANALYZE statement for the shown query. Thi= +s=20 +query is currently taking 570 msec, an OK amount of time until you realize= +=20 +that the system only has test data currently, and the tables in full=20 +production will have 100-1000 times as much data. + + Becuase it's 7.2.4, it's a little hard to tell exactly which part of the= +=20 +query is taking up 90% of the processing time. The line which claims to = +be=20 +taking that time is: + -> Seq Scan on users (cost=3D0.00..3595.33 rows=3D12 width=3D87) (actua= +l=20 +time=3D13.50..547.59 rows=3D41 loops=3D1) + +However, since users has only 200 records, I suspect that what's actually= +=20 +being represented here is the processing time for the PL/pgSQL procedure in= +=20 +the correlated subselect, if_addendee_conflict(). + +Questions:=20=20 +1. Can anyone confirm my analysis in the paragraph above? +2. Can anyone point out any obvious ways to speed up the query below? +3. In the query below, if_attendee_conflict needs to be run once for each= +=20 +(attorney times events) on the same day. Further, if_attendee_conflict=20 +involves a database lookup in 10-25% of cases. Given that=20 +if_attendee_conflict needs to apply complex criteria to determine whether o= +r=20 +not there is a conflict, can anyone suggest possible ways to cut down on th= +e=20 +number of required loops? + +Thanks everyone! Query and analyze follows. + + +j_test=3D> explain analyze +SELECT users.user_id, (users.fname || COALESCE(' ' || users.minit, '') || '= + '=20 +|| users.lname) as atty_name, + users.lname, + (SELECT if_addendee_conflict(users.user_id, 3272, '2003-04-15 10:00', '1= +=20 +days'::INTERVAL, + events.event_id, events.event_date, events.duration, event_cats.status, = +'30=20 +minutes') as cflt + FROM events, event_types, event_cats, event_days + WHERE events.event_id =3D event_days.event_id + and events.etype_id =3D event_types.etype_id + AND event_types.ecat_id =3D event_cats.ecat_id + AND event_days.event_day + BETWEEN '2003-04-15' AND '2003-04-16 10:00'=20 + ORDER BY cflt LIMIT 1) AS conflict +FROM users=20 +WHERE EXISTS (SELECT teams_users.user_id FROM teams_users JOIN teams_tree + ON teams_users.team_id =3D teams_tree.team_id WHERE teams_tree.treeno + BETWEEN 3 and 4 AND teams_users.user_id =3D users.user_id) +AND users.status > 0 + AND NOT EXISTS (SELECT staff_id FROM event_staff WHERE event_id =3D 3272 + AND staff_id =3D users.user_id)=20 +ORDER BY conflict, users.lname, atty_name; + +NOTICE: QUERY PLAN: + +Sort (cost=3D3595.55..3595.55 rows=3D12 width=3D87) (actual time=3D547.89.= +.547.91=20 +rows=3D41 loops=3D1) + -> Seq Scan on users (cost=3D0.00..3595.33 rows=3D12 width=3D87) (actua= +l=20 +time=3D13.50..547.59 rows=3D41 loops=3D1) + SubPlan + -> Limit (cost=3D54.03..54.03 rows=3D1 width=3D46) (actual=20 +time=3D13.14..13.14 rows=3D1 loops=3D41) + -> Sort (cost=3D54.03..54.03 rows=3D1 width=3D46) (actual= +=20 +time=3D13.13..13.13 rows=3D2 loops=3D41) + -> Hash Join (cost=3D52.77..54.02 rows=3D1 width=3D= +46)=20 +(actual time=3D5.09..12.94 rows=3D95 loops=3D41) + -> Seq Scan on event_cats (cost=3D0.00..1.16= +=20 +rows=3D16 width=3D6) (actual time=3D0.01..0.05 rows=3D16 loops=3D41) + -> Hash (cost=3D52.77..52.77 rows=3D1 width= +=3D40)=20 +(actual time=3D4.72..4.72 rows=3D0 loops=3D41) + -> Hash Join (cost=3D49.94..52.77 rows= +=3D1=20 +width=3D40) (actual time=3D4.19..4.59 rows=3D95 loops=3D41) + -> Seq Scan on event_types=20=20 +(cost=3D0.00..2.54 rows=3D54 width=3D8) (actual time=3D0.01..0.12 rows=3D54= + loops=3D41) + -> Hash (cost=3D49.93..49.93 rows= +=3D5=20 +width=3D32) (actual time=3D4.10..4.10 rows=3D0 loops=3D41) + -> Nested Loop=20=20 +(cost=3D0.00..49.93 rows=3D5 width=3D32) (actual time=3D0.16..3.95 rows=3D9= +5 loops=3D41) + -> Seq Scan on event_d= +ays=20=20 +(cost=3D0.00..25.00 rows=3D5 width=3D4) (actual time=3D0.12..2.31 rows=3D95= + loops=3D41) + -> Index Scan using=20 +events_pkey on events (cost=3D0.00..4.97 rows=3D1 width=3D28) (actual=20 +time=3D0.01..0.01 rows=3D1 loops=3D3895) + -> Nested Loop (cost=3D0.00..19.47 rows=3D1 width=3D12) (actual= +=20 +time=3D0.04..0.04 rows=3D0 loops=3D147) + -> Index Scan using idx_teams_tree_node on teams_tree=20= +=20 +(cost=3D0.00..8.58 rows=3D2 width=3D4) (actual time=3D0.01..0.02 rows=3D2 l= +oops=3D147) + -> Index Scan using teams_users_pk on teams_users=20=20 +(cost=3D0.00..4.83 rows=3D1 width=3D8) (actual time=3D0.01..0.01 rows=3D0 l= +oops=3D252) + -> Index Scan using event_staff_table_pk on event_staff=20=20 +(cost=3D0.00..4.95 rows=3D1 width=3D4) (actual time=3D0.01..0.01 rows=3D0 l= +oops=3D41) +Total runtime: 548.20 msec + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 20:21:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7D0A9475458 + for ; + Wed, 9 Apr 2003 20:21:14 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 6EF32474E42 + for ; + Wed, 9 Apr 2003 20:21:13 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3A0Kb2L011733; + Wed, 9 Apr 2003 20:20:38 -0400 (EDT) +To: jim@nasby.net +Cc: "scott.marlowe" , + Matthew Nuzum , "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Caching (was Re: choosing the right platform) +In-reply-to: <20030409184744.W31861@flake.decibel.org> +References: <00a001c2febb$631141d0$6900a8c0@mattspc> + + <20030409184744.W31861@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Wed, 09 Apr 2003 18:47:44 -0500" +Date: Wed, 09 Apr 2003 20:20:37 -0400 +Message-ID: <11732.1049934037@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/98 +X-Sequence-Number: 1604 + +"Jim C. Nasby" writes: +> That seems odd... shouldn't pgsql be able to cache information better +> since it would be cached in whatever format is best for it, rather than +> the raw page format (or maybe that is the best format). There's also the +> issue of having to go through more layers of software if you're relying +> on the OS caching. All the tuning info I've seen for every other +> database I've worked with specifically recommends giving the database as +> much memory as you possibly can, the theory being that it will do a much +> better job of caching than the OS will. + +There are a number of reasons why that's a dubious policy for PG (I +won't take a position on whether these apply to other databases...) + +One is that because we sit on top of the OS' filesystem, we can't +(portably) prevent the OS from caching blocks. So it's quite easy to +get into a situation where the same data is cached twice, once in PG +buffers and once in kernel disk cache. That's clearly a waste of RAM +however you slice it, and it's worst when you set the PG shared buffer +size to be about half of available RAM. You can minimize the +duplication by skewing the allocation one way or the other: either set +PG's allocation relatively small, relying heavily on the OS to do the +caching; or make PG's allocation most of RAM and hope to squeeze out +the OS' cache. There are partisans for both approaches on this list. +I lean towards the first policy because I think that starving the kernel +for RAM is a bad idea. (Especially if you run on Linux, where this +policy tempts the kernel to start kill -9'ing random processes ...) + +Another reason is that PG uses a simplistic fixed-number-of-buffers +internal cache, and therefore it can't adapt on-the-fly to varying +memory pressure, whereas the kernel can and will give up disk cache +space to make room when it's needed for processes. Since PG isn't +even aware of the total memory pressure on the system as a whole, +it couldn't do as good a job of trading off cache vs process workspace +as the kernel can do, even if we had a variable-size cache scheme. + +A third reason is that on many (most?) Unixen, SysV shared memory is +subject to swapping, and the bigger you make the shared_buffer arena, +the more likely it gets that some of the arena will be touched seldom +enough to make it a candidate for swapping. A disk buffer that gets +swapped to disk is worse than useless (if it's dirty, the swapping +is downright counterproductive, since an extra read and write cycle +will be needed before the data can make it to its rightful place). + +PG is *not* any smarter about the usage patterns of its disk buffers +than the kernel is; it uses a simple LRU algorithm that is surely no +brighter than what the kernel uses. (We have looked at smarter buffer +recycling rules, but failed to see any performance improvement.) So the +notion that PG can do a better job of cache management than the kernel +is really illusory. About the only advantage you gain from having data +directly in PG buffers rather than kernel buffers is saving the CPU +effort needed to move data across the userspace boundary --- which is +not zero, but it's sure a lot less than the time spent for actual I/O. + +So my take on it is that you want shared_buffers fairly small, and let +the kernel do the bulk of the heavy lifting for disk cache. That's what +it does for a living, so let it do what it does best. You only want +shared_buffers big enough so you don't spend too many CPU cycles shoving +data back and forth between PG buffers and kernel disk cache. The +default shared_buffers setting of 64 is surely too small :-(, but my +feeling is that values in the low thousands are enough to get past the +knee of that curve in most cases. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 20:51:31 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9C195475AE5 + for ; + Wed, 9 Apr 2003 20:51:27 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 6DCB4475A8D + for ; + Wed, 9 Apr 2003 20:51:21 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3A0pN2L011861; + Wed, 9 Apr 2003 20:51:23 -0400 (EDT) +To: josh@agliodbs.com +Cc: Pgsql-Performance +Subject: Re: Help analyzing 7.2.4 EXPLAIN +In-reply-to: <200304091715.19565.josh@agliodbs.com> +References: <200304091715.19565.josh@agliodbs.com> +Comments: In-reply-to Josh Berkus + message dated "Wed, 09 Apr 2003 17:15:19 -0700" +Date: Wed, 09 Apr 2003 20:51:23 -0400 +Message-ID: <11860.1049935883@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/99 +X-Sequence-Number: 1605 + +Josh Berkus writes: +> Becuase it's 7.2.4, it's a little hard to tell exactly which part of the +> query is taking up 90% of the processing time. + +Keep in mind that in the subqueries, the "actual time" shown is the time +per iteration --- you should multiply by the "loops" value to get an +accurate idea of where the time is going. With that in mind, it's real +clear that the first subplan is eating the bulk of the time. + +I think you are probably right that execution of the +if_addendee_conflict() function is the main cost. But +given this subquery that's not too surprising: + +> (SELECT if_addendee_conflict(users.user_id, 3272, '2003-04-15 10:00', '1 days'::INTERVAL, +> events.event_id, events.event_date, events.duration, event_cats.status, '30 minutes') as cflt +> FROM events, event_types, event_cats, event_days +> WHERE events.event_id = event_days.event_id +> and events.etype_id = event_types.etype_id +> AND event_types.ecat_id = event_cats.ecat_id +> AND event_days.event_day +> BETWEEN '2003-04-15' AND '2003-04-16 10:00' +> ORDER BY cflt LIMIT 1) AS conflict + +What you have here is a subquery that will execute +if_addendee_conflict() for *each* row of the events table; then throw +away all but one of the results. And then do that over again for each +user row. It looks to me like if_addendee_conflict() is being called +nearly 4000 times in this query. No wonder it's slow. + +The first thing that pops to mind is whether you really need the *first* +conflict, or would it be enough to find any old conflict? If you could +dispense with the ORDER BY then at least some evaluations of +if_addendee_conflict() could be saved. + +Realistically, though, I think you're going to have to refactor the work +to make this perform reasonably. How much of what +if_addendee_conflict() does is actually dependent on the user_id? Could +you separate out tests that depend only on the event, and do that in a +separate pass that is done only once per event, instead once per +event*user? If you could reduce the number of events that need to be +examined for any given user, you could get somewhere. + +Also, I don't see where this query checks to see if the user is actually +interested in attending the event. Is that one of the things +if_addendee_conflict checks? If so, you should pull it out and make it +a join condition. You're essentially forcing the stupidest possible +join algorithm by burying that condition inside a user-defined function. +It would win to check that sooner instead of later, since presumably the +set of interesting events for any one user is a lot smaller than the set +of all events. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 21:15:38 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 01C25476305 + for ; + Wed, 9 Apr 2003 21:15:36 -0400 (EDT) +Received: from ms-smtp-03.tampabay.rr.com (ms-smtp-03.tampabay.rr.com + [65.32.1.41]) by postgresql.org (Postfix) with ESMTP id 7FE97476302 + for ; + Wed, 9 Apr 2003 21:15:34 -0400 (EDT) +Received: from mattspc (169-52.34-65.tampabay.rr.com [65.34.52.169]) + by ms-smtp-03.tampabay.rr.com (8.12.5/8.12.5) with ESMTP id + h3A1FBbm021581; Wed, 9 Apr 2003 21:15:11 -0400 (EDT) +From: "Matthew Nuzum" +To: "'Pgsql-Performance'" +Cc: "'scott.marlowe'" , + "'Matthew Nuzum'" , + "'Josh Berkus'" , , + "'Tom Lane'" +Subject: Re: Caching (was Re: choosing the right platform) +Date: Wed, 9 Apr 2003 21:15:05 -0400 +Message-ID: <000501c2fefe$9f82c150$6900a8c0@mattspc> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4510 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +In-Reply-To: <11732.1049934037@sss.pgh.pa.us> +X-Spam-Status: No, hits=-13.0 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/100 +X-Sequence-Number: 1606 + +Thanks for all the feedback, this is very informative. + +My current issues that I'm still not clear on, are: +* Is the ia32 architecture going to impose uncomfortable limits on my +application? I'm seeing lots of confirmation that this platform, regardless +of the OS is going to limit me to less the 4GB of memory allocated to a +single application (i.e. http://www.spack.org/index.cgi/LinuxRamLimits). +This may or may not be an issue because: (note that these are questions, not +statements) +** Postgres is multi-process, not multi-threaded (?) +** It's better to not use huge amount of sort-mem but instead let the OS do +the caching (?) +** My needs are really not going to be as big as I think they are if I +manage the application/environment correctly (?) + +Here are some of the performance suggestions I've heard, please, if I +mis-understood, could you help me get clarity? +* It's better to run fewer apache children and turn off persistent +connections (I had suggested 200 children per server, someone else suggested +40) +* FreeBSD is going to provide a better file system than Linux (because Linux +only supports large files on journaling filesystems which impose extra over +head) (this gleaned from this conversation and previous threads in archives) +* Running Linux or *BSD on a 64 bit platform can alleviate some potential +RAM limitations (if there are truly going to be limitations). If this is +so, I've heard suggestions for Itanium, Sparc and RS/6000. Maybe someone +can give some more info on these, here are my immediate thoughts: I've heard +that the industry as a whole has not yet warmed up to Itanium. I can't +afford the newest Sparc Servers, so I'd need to settle with a previous +generation if I went that route, any problems with that? I know nothing +about the RS/6000 servers (I did see one once though :-), does linux|*BSD +run well on them and any suggestions for series/models I should look at? + +Finally, some specific questions, +What's the max number of connections someone has seen on a database server? +What type of hardware was it? How much RAM did postgres use? + +Thanks again, + +-- +Matthew Nuzum +www.bearfruit.org +cobalt@bearfruit.org +=20 +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance- +> owner@postgresql.org] On Behalf Of Tom Lane +> Sent: Wednesday, April 09, 2003 8:21 PM +> To: jim@nasby.net +> Cc: scott.marlowe; Matthew Nuzum; 'Josh Berkus'; 'Pgsql-Performance' +> Subject: Caching (was Re: [PERFORM] choosing the right platform) +>=20 +> "Jim C. Nasby" writes: +> > That seems odd... shouldn't pgsql be able to cache information better +> > since it would be cached in whatever format is best for it, rather than +> > the raw page format (or maybe that is the best format). There's also the +> > issue of having to go through more layers of software if you're relying +> > on the OS caching. All the tuning info I've seen for every other +> > database I've worked with specifically recommends giving the database as +> > much memory as you possibly can, the theory being that it will do a much +> > better job of caching than the OS will. +>=20 +> There are a number of reasons why that's a dubious policy for PG (I +> won't take a position on whether these apply to other databases...) +>=20 +> One is that because we sit on top of the OS' filesystem, we can't +> (portably) prevent the OS from caching blocks. So it's quite easy to +> get into a situation where the same data is cached twice, once in PG +> buffers and once in kernel disk cache. That's clearly a waste of RAM +> however you slice it, and it's worst when you set the PG shared buffer +> size to be about half of available RAM. You can minimize the +> duplication by skewing the allocation one way or the other: either set +> PG's allocation relatively small, relying heavily on the OS to do the +> caching; or make PG's allocation most of RAM and hope to squeeze out +> the OS' cache. There are partisans for both approaches on this list. +> I lean towards the first policy because I think that starving the kernel +> for RAM is a bad idea. (Especially if you run on Linux, where this +> policy tempts the kernel to start kill -9'ing random processes ...) +>=20 +> Another reason is that PG uses a simplistic fixed-number-of-buffers +> internal cache, and therefore it can't adapt on-the-fly to varying +> memory pressure, whereas the kernel can and will give up disk cache +> space to make room when it's needed for processes. Since PG isn't +> even aware of the total memory pressure on the system as a whole, +> it couldn't do as good a job of trading off cache vs process workspace +> as the kernel can do, even if we had a variable-size cache scheme. +>=20 +> A third reason is that on many (most?) Unixen, SysV shared memory is +> subject to swapping, and the bigger you make the shared_buffer arena, +> the more likely it gets that some of the arena will be touched seldom +> enough to make it a candidate for swapping. A disk buffer that gets +> swapped to disk is worse than useless (if it's dirty, the swapping +> is downright counterproductive, since an extra read and write cycle +> will be needed before the data can make it to its rightful place). +>=20 +> PG is *not* any smarter about the usage patterns of its disk buffers +> than the kernel is; it uses a simple LRU algorithm that is surely no +> brighter than what the kernel uses. (We have looked at smarter buffer +> recycling rules, but failed to see any performance improvement.) So the +> notion that PG can do a better job of cache management than the kernel +> is really illusory. About the only advantage you gain from having data +> directly in PG buffers rather than kernel buffers is saving the CPU +> effort needed to move data across the userspace boundary --- which is +> not zero, but it's sure a lot less than the time spent for actual I/O. +>=20 +> So my take on it is that you want shared_buffers fairly small, and let +> the kernel do the bulk of the heavy lifting for disk cache. That's what +> it does for a living, so let it do what it does best. You only want +> shared_buffers big enough so you don't spend too many CPU cycles shoving +> data back and forth between PG buffers and kernel disk cache. The +> default shared_buffers setting of 64 is surely too small :-(, but my +> feeling is that values in the low thousands are enough to get past the +> knee of that curve in most cases. +>=20 +> regards, tom lane +>=20 +>=20 +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: Have you searched our list archives? +>=20 +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 21:16:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B43AD474E42 + for ; + Wed, 9 Apr 2003 21:16:42 -0400 (EDT) +Received: from ms-smtp-01.tampabay.rr.com (ms-smtp-01.tampabay.rr.com + [65.32.1.43]) by postgresql.org (Postfix) with ESMTP id 15763475ECE + for ; + Wed, 9 Apr 2003 21:16:38 -0400 (EDT) +Received: from mattspc (169-52.34-65.tampabay.rr.com [65.34.52.169]) + by ms-smtp-01.tampabay.rr.com (8.12.5/8.12.5) with ESMTP id + h3A1Gfn6021298 for ; + Wed, 9 Apr 2003 21:16:41 -0400 (EDT) +From: "Matthew Nuzum" +To: "'Pgsql-Performance'" +Subject: Caching (was Re: choosing the right platform) +Date: Wed, 9 Apr 2003 21:16:36 -0400 +Organization: Bearfruit.org +Message-ID: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: quoted-printable +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.4510 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-9.8 required=5.0 tests=BAYES_01,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/101 +X-Sequence-Number: 1607 + +Thanks for all the feedback, this is very informative. + +My current issues that I'm still not clear on, are: +* Is the ia32 architecture going to impose uncomfortable limits on my +application? I'm seeing lots of confirmation that this platform, regardless +of the OS is going to limit me to less the 4GB of memory allocated to a +single application (i.e. http://www.spack.org/index.cgi/LinuxRamLimits). +This may or may not be an issue because: (note that these are questions, not +statements) +** Postgres is multi-process, not multi-threaded (?) +** It's better to not use huge amount of sort-mem but instead let the OS do +the caching (?) +** My needs are really not going to be as big as I think they are if I +manage the application/environment correctly (?) + +Here are some of the performance suggestions I've heard, please, if I +mis-understood, could you help me get clarity? +* It's better to run fewer apache children and turn off persistent +connections (I had suggested 200 children per server, someone else suggested +40) +* FreeBSD is going to provide a better file system than Linux (because Linux +only supports large files on journaling filesystems which impose extra over +head) (this gleaned from this conversation and previous threads in archives) +* Running Linux or *BSD on a 64 bit platform can alleviate some potential +RAM limitations (if there are truly going to be limitations). If this is +so, I've heard suggestions for Itanium, Sparc and RS/6000. Maybe someone +can give some more info on these, here are my immediate thoughts: I've heard +that the industry as a whole has not yet warmed up to Itanium. I can't +afford the newest Sparc Servers, so I'd need to settle with a previous +generation if I went that route, any problems with that? I know nothing +about the RS/6000 servers (I did see one once though :-), does linux|*BSD +run well on them and any suggestions for series/models I should look at? + +Finally, some specific questions, +What's the max number of connections someone has seen on a database server? +What type of hardware was it? How much RAM did postgres use? + +Thanks again, + +-- +Matthew Nuzum +www.bearfruit.org +cobalt@bearfruit.org +=20 +> -----Original Message----- +> From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance- +> owner@postgresql.org] On Behalf Of Tom Lane +> Sent: Wednesday, April 09, 2003 8:21 PM +> To: jim@nasby.net +> Cc: scott.marlowe; Matthew Nuzum; 'Josh Berkus'; 'Pgsql-Performance' +> Subject: Caching (was Re: [PERFORM] choosing the right platform) +>=20 +> "Jim C. Nasby" writes: +> > That seems odd... shouldn't pgsql be able to cache information better +> > since it would be cached in whatever format is best for it, rather than +> > the raw page format (or maybe that is the best format). There's also the +> > issue of having to go through more layers of software if you're relying +> > on the OS caching. All the tuning info I've seen for every other +> > database I've worked with specifically recommends giving the database as +> > much memory as you possibly can, the theory being that it will do a much +> > better job of caching than the OS will. +>=20 +> There are a number of reasons why that's a dubious policy for PG (I +> won't take a position on whether these apply to other databases...) +>=20 +> One is that because we sit on top of the OS' filesystem, we can't +> (portably) prevent the OS from caching blocks. So it's quite easy to +> get into a situation where the same data is cached twice, once in PG +> buffers and once in kernel disk cache. That's clearly a waste of RAM +> however you slice it, and it's worst when you set the PG shared buffer +> size to be about half of available RAM. You can minimize the +> duplication by skewing the allocation one way or the other: either set +> PG's allocation relatively small, relying heavily on the OS to do the +> caching; or make PG's allocation most of RAM and hope to squeeze out +> the OS' cache. There are partisans for both approaches on this list. +> I lean towards the first policy because I think that starving the kernel +> for RAM is a bad idea. (Especially if you run on Linux, where this +> policy tempts the kernel to start kill -9'ing random processes ...) +>=20 +> Another reason is that PG uses a simplistic fixed-number-of-buffers +> internal cache, and therefore it can't adapt on-the-fly to varying +> memory pressure, whereas the kernel can and will give up disk cache +> space to make room when it's needed for processes. Since PG isn't +> even aware of the total memory pressure on the system as a whole, +> it couldn't do as good a job of trading off cache vs process workspace +> as the kernel can do, even if we had a variable-size cache scheme. +>=20 +> A third reason is that on many (most?) Unixen, SysV shared memory is +> subject to swapping, and the bigger you make the shared_buffer arena, +> the more likely it gets that some of the arena will be touched seldom +> enough to make it a candidate for swapping. A disk buffer that gets +> swapped to disk is worse than useless (if it's dirty, the swapping +> is downright counterproductive, since an extra read and write cycle +> will be needed before the data can make it to its rightful place). +>=20 +> PG is *not* any smarter about the usage patterns of its disk buffers +> than the kernel is; it uses a simple LRU algorithm that is surely no +> brighter than what the kernel uses. (We have looked at smarter buffer +> recycling rules, but failed to see any performance improvement.) So the +> notion that PG can do a better job of cache management than the kernel +> is really illusory. About the only advantage you gain from having data +> directly in PG buffers rather than kernel buffers is saving the CPU +> effort needed to move data across the userspace boundary --- which is +> not zero, but it's sure a lot less than the time spent for actual I/O. +>=20 +> So my take on it is that you want shared_buffers fairly small, and let +> the kernel do the bulk of the heavy lifting for disk cache. That's what +> it does for a living, so let it do what it does best. You only want +> shared_buffers big enough so you don't spend too many CPU cycles shoving +> data back and forth between PG buffers and kernel disk cache. The +> default shared_buffers setting of 64 is surely too small :-(, but my +> feeling is that values in the low thousands are enough to get past the +> knee of that curve in most cases. +>=20 +> regards, tom lane +>=20 +>=20 +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: Have you searched our list archives? +>=20 +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 23:39:37 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D4E33475AE5 + for ; + Wed, 9 Apr 2003 23:39:33 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 01C73474E42 + for ; + Wed, 9 Apr 2003 23:39:32 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2954218; Wed, 09 Apr 2003 20:39:31 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Tom Lane +Subject: Re: Help analyzing 7.2.4 EXPLAIN +Date: Wed, 9 Apr 2003 20:39:00 -0700 +User-Agent: KMail/1.4.3 +Cc: Pgsql-Performance +References: <200304091715.19565.josh@agliodbs.com> + <11860.1049935883@sss.pgh.pa.us> +In-Reply-To: <11860.1049935883@sss.pgh.pa.us> +MIME-Version: 1.0 +Message-Id: <200304092039.00376.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.2 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,QUOTE_TWICE_1, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/102 +X-Sequence-Number: 1608 + +Tom, + +> Keep in mind that in the subqueries, the "actual time" shown is the time +> per iteration --- you should multiply by the "loops" value to get an +> accurate idea of where the time is going. With that in mind, it's real +> clear that the first subplan is eating the bulk of the time. + +Thanks, that's what I thought, but I wanted confirmation. + +> The first thing that pops to mind is whether you really need the *first* +> conflict, or would it be enough to find any old conflict? If you could +> dispense with the ORDER BY then at least some evaluations of +> if_addendee_conflict() could be saved. + +The problem is that I need the lowest-sorted non-NULL conflict. The major= +ity=20 +(95%) of the runs of if_attendee_conflict will return NULL. But we can't= +=20 +know that until we run the test, which is a bit too complex for a case=20 +statement. + +Now, if I could figure out a way to stop testing for a particular user the= +=20 +first time if_attendee_conflict returned a particular result, that could cu= +t=20 +the number of subquery loops by 1/3. Any ideas? + +> Realistically, though, I think you're going to have to refactor the work +> to make this perform reasonably. How much of what +> if_addendee_conflict() does is actually dependent on the user_id?=20=20 + +Almost all of it. The question being answered by the query is "Please give= + me=20 +the list of all users, plus which of them have a conflict for that particul= +ar=20 +date and time and what kind of conflict it is". + +>Could +> you separate out tests that depend only on the event, and do that in a +> separate pass that is done only once per event, instead once per +> event*user? If you could reduce the number of events that need to be +> examined for any given user, you could get somewhere. + +Regrettably, no. We have to run it for each user. I was acutally hoping = +to=20 +come up with a way of running for less events, acutally .... + +> +> Also, I don't see where this query checks to see if the user is actually +> interested in attending the event. Is that one of the things +> if_addendee_conflict checks?=20 + +No. the users aren't given a choice about what they want to attend = +--=20 +the purpose of the query is to supply the calendar staff with a list of who= +'s=20 +available so the users can be assigned -- whether they want to or not. + +Well, we'll see if the current incarnation bogs down in a couple of months,= +=20 +and I'll rework the query if so. Thanks for the advice! + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 9 23:46:12 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7A8B0475CEE + for ; + Wed, 9 Apr 2003 23:46:06 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 0716D474E42 + for ; + Wed, 9 Apr 2003 23:46:02 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2954227; Wed, 09 Apr 2003 20:46:00 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Matthew Nuzum" , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +Date: Wed, 9 Apr 2003 20:45:29 -0700 +User-Agent: KMail/1.4.3 +References: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +In-Reply-To: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +MIME-Version: 1.0 +Message-Id: <200304092045.29503.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/103 +X-Sequence-Number: 1609 + +Matthew, + +> ** Postgres is multi-process, not multi-threaded (?) + +Correct. + +> ** It's better to not use huge amount of sort-mem but instead let the OS = +do +> the caching (?) + +That's "don't use a huge amount of *shared_buffers*". Sort_mem is a differ= +ent=20 +setting. However, I have never seen a database use more than 32mb sort mem= +=20 +in a single process, so I don't think the 2GB limit will hurt you much ... + +> ** My needs are really not going to be as big as I think they are if I +> manage the application/environment correctly (?) + +Your needs *per process*. Also, PostgreSQL is not as much of a consumer o= +f=20 +RAM as it is a consumer of disk I/O. + +> * FreeBSD is going to provide a better file system than Linux (because +> Linux only supports large files on journaling filesystems which impose +> extra over head) (this gleaned from this conversation and previous threads +> in archives)=20 + +No, the jury is still out on this one. ReiserFS is optimized for small=20 +files, and I've done well with it although some posters report stability=20 +problems, though all second-hand. We hope to test this sometime in the=20 +upcoming months. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 04:18:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3BE3F47634D + for ; + Thu, 10 Apr 2003 04:18:12 -0400 (EDT) +Received: from lakemtao03.cox.net (lakemtao03.cox.net [68.1.17.242]) + by postgresql.org (Postfix) with ESMTP id 3ED5A47632D + for ; + Thu, 10 Apr 2003 04:18:07 -0400 (EDT) +Received: from haggis ([68.11.66.83]) by lakemtao03.cox.net + (InterMail vM.5.01.04.05 201-253-122-122-105-20011231) with ESMTP + id <20030410081808.VXUN23518.lakemtao03.cox.net@haggis> + for ; + Thu, 10 Apr 2003 04:18:08 -0400 +Subject: Re: Caching (was Re: choosing the right platform) +From: Ron Johnson +To: 'Pgsql-Performance' +In-Reply-To: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +References: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +Content-Type: text/plain +Organization: +Message-Id: <1049962679.13873.107.camel@haggis> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.3 +Date: 10 Apr 2003 03:17:59 -0500 +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-44.3 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_LONG_DENSE, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/104 +X-Sequence-Number: 1610 + +On Wed, 2003-04-09 at 20:16, Matthew Nuzum wrote: +> Thanks for all the feedback, this is very informative. +[snip] +> * Running Linux or *BSD on a 64 bit platform can alleviate some potential +> RAM limitations (if there are truly going to be limitations). If this is +> so, I've heard suggestions for Itanium, Sparc and RS/6000. Maybe someone +> can give some more info on these, here are my immediate thoughts: I've heard +> that the industry as a whole has not yet warmed up to Itanium. I can't +> afford the newest Sparc Servers, so I'd need to settle with a previous +> generation if I went that route, any problems with that? I know nothing +> about the RS/6000 servers (I did see one once though :-), does linux|*BSD +> run well on them and any suggestions for series/models I should look at? + +If you want 64-bit, maybe wait for Operon, or look at Alphas. You could +probably get a used DS20 or ES40 for a pretty good price, and Linux is +*well* supported on Alpha. If you want something that really smokes, +and have some buck lying around, try an ES47. + +-- ++----------------------------------------------------------------+ +| Ron Johnson, Jr. mailto:ron.l.johnson@cox.net | +| Jefferson, LA USA http://members.cox.net/ron.l.johnson | +| | +| "A C program is like a fast dance on a newly waxed dance floor | +| by people carrying razors." | +| Waldi Ravens | ++----------------------------------------------------------------+ + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 05:34:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5B78E4763CE + for ; + Thu, 10 Apr 2003 05:34:40 -0400 (EDT) +Received: from envy.ph.ed.ac.uk (envy.ph.ed.ac.uk [129.215.72.168]) + by postgresql.org (Postfix) with ESMTP id 2E35B4763C3 + for ; + Thu, 10 Apr 2003 05:34:35 -0400 (EDT) +Received: from jensen.ph.ed.ac.uk (jensen.ph.ed.ac.uk [129.215.73.47]) + by envy.ph.ed.ac.uk (8.9.3p2/8.9.3) with ESMTP id KAA18948; + Thu, 10 Apr 2003 10:34:36 +0100 (BST) +Received: (from dmckain1@localhost) + by jensen.ph.ed.ac.uk (8.11.6/8.11.6) id h3A9YZp15671; + Thu, 10 Apr 2003 10:34:35 +0100 +Date: Thu, 10 Apr 2003 10:34:35 +0100 +From: David McKain +To: Matthew Nuzum +Cc: "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +Message-ID: <20030410103435.B16757@ph.ed.ac.uk> +References: <000601c2fefe$d4b07e80$6900a8c0@mattspc> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <000601c2fefe$d4b07e80$6900a8c0@mattspc>; + from cobalt@bearfruit.org on Wed, Apr 09, 2003 at 09:16:36PM -0400 +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/105 +X-Sequence-Number: 1611 + +On Wed, Apr 09, 2003 at 09:16:36PM -0400, Matthew Nuzum wrote: +> Thanks for all the feedback, this is very informative. +> +> Here are some of the performance suggestions I've heard, please, if I +> mis-understood, could you help me get clarity? +> * It's better to run fewer apache children and turn off persistent +> connections (I had suggested 200 children per server, someone else suggested +> 40) + +Hi Matthew, + +I'm coming in a bit late and slightly OT here, but one common Apache +solution you might want to look at is a "reverse proxy" configuration. +This works very well if there's a good proportion of static vs dynamic +content on your site - if your pages contain a lot of graphics then this +may well be the case. + +To do this, you compile 2 Apache servers listening on different ports on +the same machine (or you can have them on different machines too). + +Server 1 (we'll call the "front server") is just a vanilla Apache +listening on Port 80, compiled with mod_rewrite and mod_proxy but +nothing else. + +Server 2 ("back server" or "heavy server") has mod_php and anything else +you need which is quite bulky (e.g. XML processing stuff, mod_perl ...) +It can listen on Port 8080 or something. Your persistent DB connections +come from Server 2. + +All web requests come in to Server 1 in the normal way and Server 1 +deals with static content as before. By setting up Apache rewrite rules +on Server 1, requests for *.php and other dynamic stuff can be forwarded +to Server 2 for processing. Server 2 returns its response back through +Server 1 and the end-user is oblivious to what's going on. (Server 2 +and/or your firewall can be configured to allow connections only from +Server 1 too.) + +It's a bit of effort to set up and does require a wee bit more +maintenance than a single server but it comes with a few nice +advantages: + +* You can have a lower MaxClients setting on server 2 and hence less + persistent DB connections and less memory used by heavy Apache modules + and PostgreSQL instances. + +* Server 1 is nice and light - no DB, low memory use (much of which is + probably shared) - so you can set its MaxClients much higher. + +* The overall impact of each dynamic page is lower as all of the + images and stylesheets it references can be quickly dealt with by + Server 1, rather than wasting an unnecessary wodge of memory and + persistent DB connection. + +I used this recently for transforming XML web pages into HTML using XSLT +and mod_perl on a slightly old and underpowered Solaris server and it +worked really well. Of course, YMMV! + +There are lots of tutorials on setting this up on the web - the mod_perl +guide has some very handy stuff in it which ought to apply reasonably +well to PHP too: + +http://perl.apache.org/docs/1.0/guide/scenario.html + +Hope that might help, +David. + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 05:58:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 27DBE476398 + for ; + Thu, 10 Apr 2003 05:58:48 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 13B83476393 + for ; + Thu, 10 Apr 2003 05:58:46 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h3A9wlF06691 + for ; Thu, 10 Apr 2003 15:28:47 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h3A9wla06685 + for ; Thu, 10 Apr 2003 15:28:47 +0530 +From: Shridhar Daithankar +To: "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +Date: Thu, 10 Apr 2003 15:29:05 +0530 +User-Agent: KMail/1.5 +References: <000601c2fefe$d4b07e80$6900a8c0@mattspc> + <20030410103435.B16757@ph.ed.ac.uk> +In-Reply-To: <20030410103435.B16757@ph.ed.ac.uk> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304101529.05217.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/106 +X-Sequence-Number: 1612 + +On Thursday 10 April 2003 15:04, you wrote: +> On Wed, Apr 09, 2003 at 09:16:36PM -0400, Matthew Nuzum wrote: +> > Thanks for all the feedback, this is very informative. +> > +> > Here are some of the performance suggestions I've heard, please, if I +> > mis-understood, could you help me get clarity? +> > * It's better to run fewer apache children and turn off persistent +> > connections (I had suggested 200 children per server, someone else +> > suggested 40) +> +> Hi Matthew, +> +> I'm coming in a bit late and slightly OT here, but one common Apache +> solution you might want to look at is a "reverse proxy" configuration. +> This works very well if there's a good proportion of static vs dynamic +> content on your site - if your pages contain a lot of graphics then this +> may well be the case. +> +> To do this, you compile 2 Apache servers listening on different ports on + +Umm.. AFAIK, if you use fastCGI, persistence of connection should be a lot +better and or OAS Server, which gives you explicit control +on how much resources to allocate. + + Shridhar + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 10:26:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 1FFDF475F16 + for ; + Thu, 10 Apr 2003 10:26:42 -0400 (EDT) +Received: from beamish.nsd.ca (beamish.nsd.ca [205.150.156.194]) + by postgresql.org (Postfix) with ESMTP id 9EB0D475CEE + for ; + Thu, 10 Apr 2003 10:26:34 -0400 (EDT) +Received: (from smap@localhost) by beamish.nsd.ca (8.9.3/8.9.3) id KAA12467; + Thu, 10 Apr 2003 10:26:12 -0400 +X-Authentication-Warning: beamish.nsd.ca: smap set sender to + using -f +Received: from reddog.nsd.ca(192.168.101.30) by beamish.nsd.ca via smap + (V2.1/2.1+anti-relay+anti-spam) + id xma012460; Thu, 10 Apr 03 10:25:42 -0400 +Received: from nsd.ca (jllachan-linux.nsd.ca [192.168.101.148]) + by reddog.nsd.ca (8.8.7/8.8.7) with ESMTP id KAA01073; + Thu, 10 Apr 2003 10:20:26 -0400 +Message-ID: <3E957F44.A1106F6A@nsd.ca> +Date: Thu, 10 Apr 2003 10:27:16 -0400 +From: Jean-Luc Lachance +X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.18-24.7.x i686) +X-Accept-Language: en +MIME-Version: 1.0 +To: Tom Lane +Cc: jim@nasby.net, "scott.marlowe" , + Matthew Nuzum , "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +References: <00a001c2febb$631141d0$6900a8c0@mattspc> + + <20030409184744.W31861@flake.decibel.org> + <11732.1049934037@sss.pgh.pa.us> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-30.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,X_AUTH_WARNING autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/107 +X-Sequence-Number: 1613 + +Tom, + +What appends when PG scans a table that is is too big to fit in the +cache? +Won't the whole cache get trashed and swapped off to disk? +Shouldn't there be a way to lock some tables in PG cache? +Who about caracterizing some of the RAM like: scan, index, small +frequently used tables. + +JLL + +Tom Lane wrote: +> [...] +> PG is *not* any smarter about the usage patterns of its disk buffers +> than the kernel is; it uses a simple LRU algorithm that is surely no +> brighter than what the kernel uses. (We have looked at smarter buffer +> recycling rules, but failed to see any performance improvement.) So the +> notion that PG can do a better job of cache management than the kernel +> is really illusory. About the only advantage you gain from having data +> directly in PG buffers rather than kernel buffers is saving the CPU +> effort needed to move data across the userspace boundary --- which is +> not zero, but it's sure a lot less than the time spent for actual I/O. +> +> So my take on it is that you want shared_buffers fairly small, and let +> the kernel do the bulk of the heavy lifting for disk cache. That's what +> it does for a living, so let it do what it does best. You only want +> shared_buffers big enough so you don't spend too many CPU cycles shoving +> data back and forth between PG buffers and kernel disk cache. The +> default shared_buffers setting of 64 is surely too small :-(, but my +> feeling is that values in the low thousands are enough to get past the +> knee of that curve in most cases. + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 10:40:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 06564474E42 + for ; + Thu, 10 Apr 2003 10:40:17 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id BF5BB4762A2 + for ; + Thu, 10 Apr 2003 10:40:15 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3AEeF2L004073; + Thu, 10 Apr 2003 10:40:15 -0400 (EDT) +To: Jean-Luc Lachance +Cc: jim@nasby.net, "scott.marlowe" , + Matthew Nuzum , "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +In-reply-to: <3E957F44.A1106F6A@nsd.ca> +References: <00a001c2febb$631141d0$6900a8c0@mattspc> + + <20030409184744.W31861@flake.decibel.org> + <11732.1049934037@sss.pgh.pa.us> <3E957F44.A1106F6A@nsd.ca> +Comments: In-reply-to Jean-Luc Lachance + message dated "Thu, 10 Apr 2003 10:27:16 -0400" +Date: Thu, 10 Apr 2003 10:40:15 -0400 +Message-ID: <4072.1049985615@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/108 +X-Sequence-Number: 1614 + +Jean-Luc Lachance writes: +> Shouldn't there be a way to lock some tables in PG cache? + +In my opinion, no. I do not think a manual locking feature could +possibly be used effectively. It could very easily be abused to +decrease net performance, though :-( + +It does seem that a smarter buffer management algorithm would be a good +idea, but past experiments have failed to show any measurable benefit. +Perhaps those experiments were testing the wrong conditions. I'd still +be happy to see LRU(k) or some such method put in, if someone can prove +that it actually does anything useful for us. (As best I recall, I only +tested LRU-2 with pgbench. Perhaps Josh's benchmarking project will +offer a wider variety of interesting scenarios.) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 12:49:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E203047592C + for ; + Thu, 10 Apr 2003 12:49:00 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id AD5BA474E42 + for ; + Thu, 10 Apr 2003 12:48:56 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3AGkdRF007995; + Thu, 10 Apr 2003 10:46:39 -0600 (MDT) +Date: Thu, 10 Apr 2003 10:42:35 -0600 (MDT) +From: "scott.marlowe" +To: "Jim C. Nasby" +Cc: Matthew Nuzum , + Pgsql-Performance +Subject: Re: choosing the right platform +In-Reply-To: <20030409185843.X31861@flake.decibel.org> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/109 +X-Sequence-Number: 1615 + +On Wed, 9 Apr 2003, Jim C. Nasby wrote: + +> On Wed, Apr 09, 2003 at 10:51:34AM -0600, scott.marlowe wrote: +> > Secondly, look carefully at using persistant connections in large numbers. +> > +> > While persistant connections DO represent a big savings in connect time, +> > the savings are lost in the noise of many PHP applications. +> > +> > i.e. my dual PIII swiss army knife server can initiate single persistant +> > connections at 1,000,000 a second (reusing the old ones of course). +> > non-persistant connects happen at 1,000 times a second. Most of my +> > scripts run in 1/10th of a second or so, so the 1/1000th used to connect +> > is noise to me. +> +> My $0.02 from my experience with Sybase and DB2: +> It's not the connection *time* that's an issue, it's the amount of +> resources (mostly memory) used by each database connection. Each db2 +> connection to a database uses 4-8 meg of memory; + +Agreed. + +> on my pgsql system, +> each connection appears to be using about 4M. This is the resident set, +> which I believe indicates memory that basically can't be shared. All +> this memory is memory that can't be used for buffering/caching; on a +> system with a hundred connections, it can really start to add up. + +If I run "select * from logs" from two different psql sessions on my +backup box hitting my main box (psql would hold the result set and throw +the results off if I ran it on the main box) I get this output from top: + +No (pgsql) load: + + 8:58am up 9 days, 22:43, 4 users, load average: 0.65, 0.54, 0.35 +169 processes: 168 sleeping, 1 running, 0 zombie, 0 stopped +CPU0 states: 0.1% user, 0.1% system, 0.0% nice, 99.1% idle +CPU1 states: 32.1% user, 3.2% system, 0.0% nice, 64.0% idle +Mem: 1543980K av, 1049864K used, 494116K free, 265928K shrd, 31404K buff +Swap: 2048208K av, 0K used, 2048208K free 568600K cached + + PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND +10241 postgres 9 0 4216 4216 4136 S 0.0 0.2 0:05 postmaster +10242 postgres 9 0 4444 4444 4156 S 0.0 0.2 0:00 postmaster +10243 postgres 9 0 4812 4812 4148 S 0.0 0.3 0:00 postmaster + +1 psql select *: + 9:03am up 9 days, 22:48, 2 users, load average: 0.71, 0.71, 0.46 +166 processes: 165 sleeping, 1 running, 0 zombie, 0 stopped +CPU0 states: 0.0% user, 0.0% system, 0.0% nice, 100.0% idle +CPU1 states: 0.1% user, 2.0% system, 0.0% nice, 97.3% idle +Mem: 1543980K av, 1052188K used, 491792K free, 265928K shrd, 32036K buff +Swap: 2048208K av, 0K used, 2048208K free 570656K cached + + PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND +10241 postgres 10 0 4216 4216 4136 S 0.0 0.2 0:05 postmaster +10242 postgres 9 0 4448 4448 4156 S 0.0 0.2 0:00 postmaster +10243 postgres 9 0 4812 4812 4148 S 0.0 0.3 0:00 postmaster +18026 postgres 9 0 236M 236M 235M S 0.0 15.6 0:12 postmaster +18035 postgres 10 0 5832 5732 5096 S 0.0 0.3 0:00 postmaster + +2 psql select *: + 9:03am up 9 days, 22:49, 2 users, load average: 0.58, 0.66, 0.45 +166 processes: 165 sleeping, 1 running, 0 zombie, 0 stopped +CPU0 states: 0.0% user, 2.2% system, 0.0% nice, 97.2% idle +CPU1 states: 0.0% user, 0.0% system, 0.0% nice, 100.0% idle +Mem: 1543980K av, 1053152K used, 490828K free, 265928K shrd, 32112K buff +Swap: 2048208K av, 0K used, 2048208K free 570684K cached + + PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME COMMAND +10241 postgres 8 0 4216 4216 4136 S 0.0 0.2 0:05 postmaster +10242 postgres 9 0 4448 4448 4156 S 0.0 0.2 0:00 postmaster +10243 postgres 9 0 4812 4812 4148 S 0.0 0.3 0:00 postmaster +18026 postgres 9 0 236M 236M 235M S 0.0 15.6 0:12 postmaster +18035 postgres 9 0 236M 236M 235M S 0.0 15.6 0:12 postmaster + +The difference between SIZE and SHARE is the delta, which is only +something like 3 or 4 megs for the initial select * from logs, but the +second one is only 1 meg. On average, the actual increase in memory usage +for postgresql isn't that great, usually about 1 meg. + +Running out of memory isn't really a problem with connections<=200 and 1 +gig of ram, as long as sort_mem isn't too high. I/O contention is the +killer at that point, as is CPU load. + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 12:58:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 04643475CEE + for ; + Thu, 10 Apr 2003 12:58:03 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id DB99E475AE5 + for ; + Thu, 10 Apr 2003 12:58:01 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3AGtfRF008847; + Thu, 10 Apr 2003 10:55:41 -0600 (MDT) +Date: Thu, 10 Apr 2003 10:51:38 -0600 (MDT) +From: "scott.marlowe" +To: "Jim C. Nasby" +Cc: Matthew Nuzum , "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: choosing the right platform +In-Reply-To: <20030409184744.W31861@flake.decibel.org> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/110 +X-Sequence-Number: 1616 + +On Wed, 9 Apr 2003, Jim C. Nasby wrote: + +> On Wed, Apr 09, 2003 at 11:55:56AM -0600, scott.marlowe wrote: +> > A couple more suggestions. One is to never allocate more than 50% of your +> > memory to a database's shared buffers, i.e. let the OS buffer the disks en +> > masse, while the database should have a smaller buffer for the most recent +> > accesses. This is because kernel caching is usually faster and more +> > efficient than the database doing it, and this becomes more an issue with +> > large chunks of memory, which both Linux and BSD are quite good at +> > caching, and postgresql, not so good. +> +> That seems odd... shouldn't pgsql be able to cache information better +> since it would be cached in whatever format is best for it, rather than +> the raw page format (or maybe that is the best format). + +Yes and no. The problem isn't that the data is closer to postgresql in +it's buffers versus further away in kernel buffers, it's that postgresql's +caching algorhythm isn't performance tweaked for very large settings, it's +performance tweaked to provide good performance on smaller machines, with +say 4 or 16 Megs of shared buffers. Handling large buffers requires a +different approach to handling small ones, and the kernel is optimized in +that direction. + +Also, the kernel in most Oses, i.e. Linux and BSD tends to use "spare ram" +with abandon as cache memory, so if you've got 4 gigs of ram, with 200 +Megs set aside for postgresql, it's quite likely that the kernel cache can +hold ALL your dataset for you once it's been read in once. So, the data +is already cached once. Caching it again in Postgresql only gains a +little, since the speed difference of postgresql shared buffer / cache and +kernel caches is very small. However, the speed going to the hard drive +is much slower. + +What you don't want is a postgresql cache that's bigger (on average) than +the kernel cache, since the kernel cache will then be "thrashing" when you +access information not currently in either cache. I.e. postgresql becomes +your only cache, and kernel caching stops working for you and becomes just +overhead, since you never get anything from it if it's too small to cache +something long enough to be used again. + +> There's also the +> issue of having to go through more layers of software if you're relying +> on the OS caching. All the tuning info I've seen for every other +> database I've worked with specifically recommends giving the database as +> much memory as you possibly can, the theory being that it will do a much +> better job of caching than the OS will. + +That's old school thinking. There was a day when kernel caching was much +slower, and writing directly to your devices in a raw mode was the only +way to ensure good performance. Nowadays, most modern Unix kernels and +their file systems are a match for most database needs. heck, with some +storage systems, the performance of the file system is just not really an +issue, it's the bandwidth of the connector you use. + +Note that this is a good thing (TM) since it frees the postgresql +development team to do other things than worry about caching 1 gig of +data. + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:17:53 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 06FF4475EDF + for ; + Thu, 10 Apr 2003 13:17:50 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id D8392475AE5 + for ; + Thu, 10 Apr 2003 13:17:48 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3AHHd2L005113; + Thu, 10 Apr 2003 13:17:39 -0400 (EDT) +To: "scott.marlowe" +Cc: "Jim C. Nasby" , Matthew Nuzum , + "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: choosing the right platform +In-reply-to: +References: +Comments: In-reply-to "scott.marlowe" + message dated "Thu, 10 Apr 2003 10:51:38 -0600" +Date: Thu, 10 Apr 2003 13:17:39 -0400 +Message-ID: <5112.1049995059@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/111 +X-Sequence-Number: 1617 + +"scott.marlowe" writes: +> Note that this is a good thing (TM) since it frees the postgresql +> development team to do other things than worry about caching 1 gig of +> data. + +Yeah. I think this is one very fundamental difference of design +philosophy between Postgres and more-traditional databases such as +Oracle. We prefer to let the kernel and filesystem do their jobs, +and we assume they will do them well; whereas Oracle wants to bypass +if not replace the kernel and filesystem. Partly this is a matter of +the PG project not having the manpower to replace those layers. But +I believe the world has changed in the last twenty years, and the Oracle +approach is now obsolete: it's now costing them design and maintenance +effort that isn't providing much return. Modern kernels and filesystems +are *good*, and it's not easy to do better. We should focus our efforts +on functionality that doesn't just duplicate what the OS can do. + +This design approach shows up in other areas too. For instance, in +another thread I was just pointing out that there is no need for our +frontend/backend protocol to solve communication problems like dropped +or duplicated packets; TCP does that perfectly well already. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:21:07 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3AEB8476331 + for ; + Thu, 10 Apr 2003 13:21:02 -0400 (EDT) +Received: from mail.nbc.attcanada.ca (tor-vs3.nbc.netcom.ca [207.181.89.35]) + by postgresql.org (Postfix) with ESMTP id 0467947632D + for ; + Thu, 10 Apr 2003 13:20:59 -0400 (EDT) +Received: from localhost (firewall.procedium.com [216.13.191.82]) + by mail.nbc.attcanada.ca (bela (1.1)/8.12.8) with ESMTP id + h3AHKn0d017896 for ; + Thu, 10 Apr 2003 13:20:58 -0400 (EDT) +Date: Thu, 10 Apr 2003 10:20:49 -0700 +From: Boris Popov +X-Mailer: The Bat! (v1.62i) Business +Reply-To: Boris Popov +Organization: Procedium Software +X-Priority: 3 (Normal) +Message-ID: <564664787.20030410102049@procedium.com> +To: pgsql-performance +Subject: Reference data for performance testing? +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-1.6 required=5.0 + tests=BAYES_30 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/112 +X-Sequence-Number: 1618 + +Hello, + +We're evaluating postgresql as a backend choice for our next +generation software and would like to perform some rough measurements +in-house. Where could I get my hands on some reference data, say few +very large tables with a total size of over 1G that we could run. I +noticed earlier discussion about Tiger data, but 30G is a bit too much +for what we need. Any other ideas or suggestions? + +Thanks. + +-- +-Boris + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:23:04 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B89A6475CEE + for ; + Thu, 10 Apr 2003 13:23:03 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id F3401475AE5 + for ; + Thu, 10 Apr 2003 13:23:02 -0400 (EDT) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2955117; Thu, 10 Apr 2003 10:22:56 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Boris Popov , + pgsql-performance +Subject: Re: Reference data for performance testing? +Date: Thu, 10 Apr 2003 10:22:50 -0700 +User-Agent: KMail/1.4.3 +References: <564664787.20030410102049@procedium.com> +In-Reply-To: <564664787.20030410102049@procedium.com> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304101022.50663.josh@agliodbs.com> +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/113 +X-Sequence-Number: 1619 + +Boris, + +> We're evaluating postgresql as a backend choice for our next +> generation software and would like to perform some rough measurements +> in-house. Where could I get my hands on some reference data, say few +> very large tables with a total size of over 1G that we could run. I +> noticed earlier discussion about Tiger data, but 30G is a bit too much +> for what we need. Any other ideas or suggestions? + +The same discussion references the FCC data, which is more managably sized. + +Please share your results, if you can! + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:24:57 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A10F547592C + for ; + Thu, 10 Apr 2003 13:24:56 -0400 (EDT) +Received: from mail.nbc.attcanada.ca (tor-vs3.nbc.netcom.ca [207.181.89.35]) + by postgresql.org (Postfix) with ESMTP id C3BA2474E42 + for ; + Thu, 10 Apr 2003 13:24:55 -0400 (EDT) +Received: from localhost (firewall.procedium.com [216.13.191.82]) + by mail.nbc.attcanada.ca (bela (1.1)/8.12.8) with ESMTP id + h3AHOq0d019974; Thu, 10 Apr 2003 13:24:54 -0400 (EDT) +Date: Thu, 10 Apr 2003 10:24:51 -0700 +From: Boris Popov +X-Mailer: The Bat! (v1.62i) Business +Reply-To: Boris Popov +Organization: Procedium Software +X-Priority: 3 (Normal) +Message-ID: <1014906905.20030410102451@procedium.com> +To: Josh Berkus +Cc: pgsql-performance +Subject: Re: Reference data for performance testing? +In-Reply-To: <200304101022.50663.josh@agliodbs.com> +References: <564664787.20030410102049@procedium.com> + <200304101022.50663.josh@agliodbs.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-29.0 required=5.0 + tests=BAYES_20,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/114 +X-Sequence-Number: 1620 + +Hello Josh, + +Thursday, April 10, 2003, 10:22:50 AM, you wrote: + +JB> Boris, + +>> We're evaluating postgresql as a backend choice for our next +>> generation software and would like to perform some rough measurements +>> in-house. Where could I get my hands on some reference data, say few +>> very large tables with a total size of over 1G that we could run. I +>> noticed earlier discussion about Tiger data, but 30G is a bit too much +>> for what we need. Any other ideas or suggestions? + +JB> The same discussion references the FCC data, which is more managably sized. + +JB> Please share your results, if you can! + + +I can't find a link right now, could you tell me where can I download it? + +-- +-Boris + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:35:30 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B397B476323 + for ; + Thu, 10 Apr 2003 13:35:29 -0400 (EDT) +Received: from hotmail.com (f85.law12.hotmail.com [64.4.19.85]) + by postgresql.org (Postfix) with ESMTP id 03454476305 + for ; + Thu, 10 Apr 2003 13:35:25 -0400 (EDT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Thu, 10 Apr 2003 10:32:49 -0700 +Received: from 200.67.80.182 by lw12fd.law12.hotmail.msn.com with HTTP; + Thu, 10 Apr 2003 17:32:49 GMT +X-Originating-IP: [200.67.80.182] +X-Originating-Email: [cecilia_ag@hotmail.com] +From: "Cecilia Alvarez" +To: pgsql-performance@postgresql.org +Subject: Slow Visual Basic application +Date: Thu, 10 Apr 2003 12:32:49 -0500 +Mime-Version: 1.0 +Content-Type: text/html; charset=iso-8859-1 +Message-ID: +X-OriginalArrivalTime: 10 Apr 2003 17:32:49.0499 (UTC) + FILETIME=[35051AB0:01C2FF87] +X-Spam-Status: No, + hits=0.0 required=5.0 tests=BAYES_30,HTML_20_30 version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/115 +X-Sequence-Number: 1621 + +
Hi,
+
I have a visual basic application and the access to postgress is very slow.
+
If I run the query on PGadminII the answer is quite good but if I run the same query from the application it takes a long time (I debugged it). 11seconds .vs. 5 minutes.
+
I would like to know if I have a problem with my connection to postgres or my odbc.
+
The string connection is:
+
 
+
gobjBD.StringConexion = "Provider=MSDataShape.1;DRIVER={PostgreSQL};DATABASE=mydatabase;
SERVER=192.9.200.5;PORT=5432;UID=postgres;PWD="
+
 
+
I�ll really apreciate your help.
+
Thanks
+
Cecilia

�nete al mayor servicio mundial de correo electr�nico: Haz clic aqu� + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 13:47:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B5F8E47592C + for ; + Thu, 10 Apr 2003 13:47:46 -0400 (EDT) +Received: from moya.trilug.org (moya.trilug.org [64.244.27.141]) + by postgresql.org (Postfix) with ESMTP id CA5E3474E42 + for ; + Thu, 10 Apr 2003 13:47:42 -0400 (EDT) +Received: from trilug.org (vpn.ccgroupnet.com [207.103.85.62]) + (using SSLv3 with cipher DES-CBC3-SHA (168/168 bits)) + (No client certificate requested) + by moya.trilug.org (Postfix) with ESMTP id 45AE6A0025 + for ; + Thu, 10 Apr 2003 13:47:40 -0400 (EDT) +Date: Thu, 10 Apr 2003 13:47:44 -0400 +Subject: Re: Reference data for performance testing? +Content-Type: text/plain; charset=US-ASCII; format=flowed +Mime-Version: 1.0 (Apple Message framework v551) +From: Chris Hedemark +To: pgsql-performance@postgresql.org +Content-Transfer-Encoding: 7bit +In-Reply-To: <564664787.20030410102049@procedium.com> +Message-Id: <88A7D7B4-6B7C-11D7-829D-0003939CC61E@trilug.org> +X-Request-Pgp: http://yonderway.com/chris/hedemark.gpg +X-Mailer: Apple Mail (2.551) +X-Spam-Status: No, hits=-28.3 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_APPLEMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/116 +X-Sequence-Number: 1622 + + +On Thursday, April 10, 2003, at 01:20 PM, Boris Popov wrote: + +> We're evaluating postgresql as a backend choice for our next +> generation software and would like to perform some rough measurements +> in-house. Where could I get my hands on some reference data, say few +> very large tables with a total size of over 1G that we could run. I +> noticed earlier discussion about Tiger data, but 30G is a bit too much +> for what we need. Any other ideas or suggestions? + +Actually Tiger is broken down into easily digestable chunks; you don't +grab all 30G at once. Pick one moderate size state to work with and +you've got about the right size data set. + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 14:58:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 26E58475AE5; Thu, 10 Apr 2003 14:58:16 -0400 (EDT) +Received: from fddlnint05.fds.com (fddlnint05.fds.com [208.15.91.52]) + by postgresql.org (Postfix) with ESMTP + id 53DCB475EFD; Thu, 10 Apr 2003 14:58:09 -0400 (EDT) +In-Reply-To: +Subject: Re: Slow Visual Basic application +To: cecilia_ag@hotmail.com +Cc: pgsql-performance@postgresql.org, + pgsql-performance-owner@postgresql.org +X-Mailer: Lotus Notes Release 6.0 September 26, 2002 +Message-ID: + +From: "Patrick Hatcher" +Date: Thu, 10 Apr 2003 11:52:45 -0700 +X-MIMETrack: Serialize by Router on FDDLNINT05/FSG/SVR/FDD(Release 5.0.4 |June + 8, 2000) at 04/10/2003 02:54:26 PM +MIME-Version: 1.0 +Content-type: text/plain; charset=iso-8859-1 +Content-transfer-encoding: quoted-printable +X-Spam-Status: No, hits=-9.0 required=5.0 tests=BAYES_10,IN_REP_TO + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/117 +X-Sequence-Number: 1623 + + +It appears you are trying to create a cube by using MSDataShape. Correct? +This could be the cause of the slow query. Why not use a straight ADO +connection? + +Dim cn As ADODB.Connection +Dim rs As ADODB.Recordset + +Set cn =3D New ADODB.Connection +Set rs =3D New ADODB.Recordset + +cn.ConnectionString =3D "driver=3D{PostgreSQL};server=3D192.9.200.5;uid=3D;= +pwd +=3D;database=3Dmydatabase" +cn.ConnectionTimeout =3D 300 +cn.CursorLocation =3D adUseClient +cn.Open + +Set rs =3D cn.Execute("Select * from table1) + + + + +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20 + "Cecilia Alvarez"=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20 + To: pgsql-perfor= +mance@postgresql.org=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 + Sent by: cc:=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 + pgsql-performance-owner@post Subject: [PERFOR= +M] Slow Visual Basic application=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20 + gresql.org=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20 +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20 +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20 + 04/10/2003 10:32 AM=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20 +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20 + + + + +Hi, +I have a visual basic application and the access to postgress is very slow. +If I run the query on PGadminII the answer is quite good but if I run the +same query from the application it takes a long time (I debugged it). +11seconds .vs. 5 minutes. +I would like to know if I have a problem with my connection to postgres or +my odbc. +The string connection is: + +gobjBD.StringConexion =3D "Provider=3DMSDataShape.1;DRIVER +=3D{PostgreSQL};DATABASE=3Dmydatabase; +SERVER=3D192.9.200.5;PORT=3D5432;UID=3Dpostgres;PWD=3D" + +I=B4ll really apreciate your help. +Thanks +Cecilia + +=DAnete al mayor servicio mundial de correo electr=F3nico: Haz clic aqu=ED + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 14:59:32 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2623D47592C + for ; + Thu, 10 Apr 2003 14:59:29 -0400 (EDT) +Received: from beamish.nsd.ca (beamish.nsd.ca [205.150.156.194]) + by postgresql.org (Postfix) with ESMTP id B4EBA474E42 + for ; + Thu, 10 Apr 2003 14:59:27 -0400 (EDT) +Received: (from smap@localhost) by beamish.nsd.ca (8.9.3/8.9.3) id OAA16964; + Thu, 10 Apr 2003 14:58:20 -0400 +X-Authentication-Warning: beamish.nsd.ca: smap set sender to + using -f +Received: from reddog.nsd.ca(192.168.101.30) by beamish.nsd.ca via smap + (V2.1/2.1+anti-relay+anti-spam) + id xma016962; Thu, 10 Apr 03 14:58:16 -0400 +Received: from nsd.ca (jllachan-linux.nsd.ca [192.168.101.148]) + by reddog.nsd.ca (8.8.7/8.8.7) with ESMTP id OAA03220; + Thu, 10 Apr 2003 14:52:59 -0400 +Message-ID: <3E95BF2B.B93FD0EF@nsd.ca> +Date: Thu, 10 Apr 2003 14:59:55 -0400 +From: Jean-Luc Lachance +X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.18-24.7.x i686) +X-Accept-Language: en +MIME-Version: 1.0 +To: Tom Lane +Cc: jim@nasby.net, "scott.marlowe" , + Matthew Nuzum , "'Josh Berkus'" , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +References: <00a001c2febb$631141d0$6900a8c0@mattspc> + + <20030409184744.W31861@flake.decibel.org> + <11732.1049934037@sss.pgh.pa.us> <3E957F44.A1106F6A@nsd.ca> + <4072.1049985615@sss.pgh.pa.us> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-30.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,X_AUTH_WARNING autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/118 +X-Sequence-Number: 1624 + +How can we solve the problem of cache trashing when scanning large +tables? + +Tom Lane wrote: +> +> Jean-Luc Lachance writes: +> > Shouldn't there be a way to lock some tables in PG cache? +> +> In my opinion, no. I do not think a manual locking feature could +> possibly be used effectively. It could very easily be abused to +> decrease net performance, though :-( +> +> It does seem that a smarter buffer management algorithm would be a good +> idea, but past experiments have failed to show any measurable benefit. +> Perhaps those experiments were testing the wrong conditions. I'd still +> be happy to see LRU(k) or some such method put in, if someone can prove +> that it actually does anything useful for us. (As best I recall, I only +> tested LRU-2 with pgbench. Perhaps Josh's benchmarking project will +> offer a wider variety of interesting scenarios.) +> +> regards, tom lane +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 19:15:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0D7DD476036 + for ; + Thu, 10 Apr 2003 19:15:08 -0400 (EDT) +Received: from torque.intervideoinc.com (mail.intervideo.com + [206.112.112.151]) + by postgresql.org (Postfix) with ESMTP id 8D840476032 + for ; + Thu, 10 Apr 2003 19:15:06 -0400 (EDT) +Received: from ronpc [63.68.5.2] by torque.intervideoinc.com + (SMTPD32-5.05) id AFBA1B60152; Thu, 10 Apr 2003 16:35:22 -0700 +From: "Ron Mayer" +To: "Josh Berkus" , "Matthew Nuzum" , + "'Pgsql-Performance'" +Cc: +Subject: Re: Caching (was Re: choosing the right platform) +Date: Thu, 10 Apr 2003 16:06:40 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +Importance: Normal +In-Reply-To: <200304092045.29503.josh@agliodbs.com> +X-Spam-Status: No, hits=-14.3 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE,SMTPD_IN_RCVD + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/119 +X-Sequence-Number: 1625 + + +Short summary... + + I think sort_mem matters quite a bit (20-40%) on + my data-warehousing applications. + + Am I doing something wrong to need so much sort_mem? + +Josh wrote: +>> ** It's better to not use huge amount of sort-mem... +> +>...However, I have never seen a database use more than 32mb sort mem +>in a single process, so I don't think the 2GB limit will hurt you much ... + +Do you think this is true in data warehousing applications as well? + +During the ETL part of data warehousing, large sorts are often +used to get the "new" values that need to be inserted +into "dimension" tables, like this: + INSERT INTO dimension_val (id,val) + SELECT nextval('val_seq'),val + FROM (SELECT DISTINCT val FROM import_table + EXCEPT + SELECT val FROM dimension_val) as a; +As far as I can tell, this query typically does two sorts, +one for the distinct, and one for the except. + + +In a data warehouse we have here, we load about 3 million rows +each week; load time improved from about 9 to 7 hours +by breaking up such queries into expressions that only require +one sort at a time, and surrounding the expressions with +"set sort_mem=something_big" statements to give it enough +space to not hit the disk. + + SET SORT_MEM=300000; + CREATE TEMPORARY TABLE potential_new_values AS + SELECT DISTINCT val FROM import_table; + ... + SET SORT_MEM=1000; + +Anyone else have similar experience, or am I doing something +wrong to need so much SORT_MEM? + + + Ron + + + +PS: + +Below is an example of another real-world query from the same +reporting system that benefits from a sort_mem over 32M. +Explain analyze (below) shows a 40% improvement by having +the sort fit in memory. + +10Meg and 32Meg take over 22 seconds. 100Meg takes 14. + +==================================================================================================== +logs2=# +logs2=# +logs2=# set sort_mem=10000; +SET VARIABLE +logs2=# explain analyze select distinct category from c_transaction_credit; +NOTICE: QUERY PLAN: + +Unique (cost=71612.82..72838.69 rows=49035 width=17) (actual time=20315.47..22457.21 rows=2914 loops=1) + -> Sort (cost=71612.82..71612.82 rows=490348 width=17) (actual time=20315.46..21351.42 rows=511368 loops=1) + -> Seq Scan on c_transaction_credit (cost=0.00..14096.48 rows=490348 width=17) (actual time=0.08..2932.72 rows=511368 +loops=1) +Total runtime: 22475.63 msec + +EXPLAIN +logs2=# set sort_mem=32000; +SET VARIABLE +logs2=# explain analyze select distinct category from c_transaction_credit; +NOTICE: QUERY PLAN: + +Unique (cost=60442.82..61668.69 rows=49035 width=17) (actual time=22657.31..24794.19 rows=2914 loops=1) + -> Sort (cost=60442.82..60442.82 rows=490348 width=17) (actual time=22657.30..23714.43 rows=511368 loops=1) + -> Seq Scan on c_transaction_credit (cost=0.00..14096.48 rows=490348 width=17) (actual time=0.07..3020.83 rows=511368 +loops=1) +Total runtime: 24811.65 msec + +EXPLAIN +logs2=# set sort_mem=100000; +SET VARIABLE +logs2=# explain analyze select distinct category from c_transaction_credit; +NOTICE: QUERY PLAN: + +Unique (cost=60442.82..61668.69 rows=49035 width=17) (actual time=12205.19..14012.57 rows=2914 loops=1) + -> Sort (cost=60442.82..60442.82 rows=490348 width=17) (actual time=12205.18..12710.16 rows=511368 loops=1) + -> Seq Scan on c_transaction_credit (cost=0.00..14096.48 rows=490348 width=17) (actual time=0.08..3001.05 rows=511368 +loops=1) +Total runtime: 14187.96 msec + +EXPLAIN +logs2=# + + +From pgsql-performance-owner@postgresql.org Thu Apr 10 20:13:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C4C48474E42 + for ; + Thu, 10 Apr 2003 20:13:34 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 03A24474E4F + for ; + Thu, 10 Apr 2003 20:13:30 -0400 (EDT) +Received: from [216.135.165.74] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2955916; Thu, 10 Apr 2003 17:13:26 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Tom Lane +Subject: Re: Help analyzing 7.2.4 EXPLAIN +Date: Thu, 10 Apr 2003 17:13:19 -0700 +User-Agent: KMail/1.4.3 +Cc: Pgsql-Performance +References: <200304091715.19565.josh@agliodbs.com> + <11860.1049935883@sss.pgh.pa.us> +In-Reply-To: <11860.1049935883@sss.pgh.pa.us> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304101713.19953.josh@agliodbs.com> +X-Spam-Status: No, hits=-22.7 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/120 +X-Sequence-Number: 1626 + +Tom, + +If you're interested, here's the query I ended up with. It's much uglier t= +han=20 +the original query, but gives me slightly more data (one bit of information= +=20 +is seperated into 2 columns rather than rolled up), is 100ms faster, and=20 +should not slow down much with the growth of the tables: + +SELECT users.user_id, (users.fname || COALESCE(' ' || users.minit, '') || '= + '=20 +|| users.lname) as atty_name, + users.lname, + COALESCE ( + (SELECT if_addendee_conflict(users.user_id, 3272, '2003-04-15 10:00', '1= +=20 +days'::INTERVAL, + events.event_id, events.event_date, events.duration, event_cats.status, + '30 minutes', staff_id) as cflt + FROM event_types, event_cats, event_days, events, event_staff + WHERE events.event_id =3D event_days.event_id + and events.etype_id =3D event_types.etype_id + AND event_types.ecat_id =3D event_cats.ecat_id + AND event_days.event_day BETWEEN '2003-04-15' AND '2003-04-16 10:00' + AND events.event_id <> 3272 + AND events.event_id =3D event_staff.event_id + AND event_staff.staff_id =3D users.user_id + AND event_cats.status IN (1,3) + ORDER BY cflt LIMIT 1), + (SELECT 'LEAVE'::TEXT + FROM event_types, event_cats, event_days, events + WHERE events.event_id =3D event_days.event_id + and events.etype_id =3D event_types.etype_id + AND event_types.ecat_id =3D event_cats.ecat_id + AND event_days.event_day BETWEEN '2003-04-15' AND '2003-04-16 10:00' + AND events.event_id <> 3272 + AND event_cats.status =3D 4) + ) AS conflict, + (SELECT (staff_id > 0) FROM event_staff + WHERE event_id =3D 3272 + AND staff_id =3D users.user_id) as assigned +FROM users +WHERE EXISTS (SELECT teams_users.user_id FROM teams_users JOIN teams_tree + ON teams_users.team_id =3D teams_tree.team_id WHERE teams_tree.treeno + BETWEEN 3 and 4 AND teams_users.user_id =3D users.user_id) + AND users.status > 0 +ORDER BY conflict, users.lname, atty_name; + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 11 11:19:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id ADCC64762D7 + for ; + Fri, 11 Apr 2003 11:19:24 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id DC0624762A2 + for ; + Fri, 11 Apr 2003 11:19:23 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3BFIBRF006302; + Fri, 11 Apr 2003 09:18:11 -0600 (MDT) +Date: Fri, 11 Apr 2003 09:14:00 -0600 (MDT) +From: "scott.marlowe" +To: Ron Mayer +Cc: Josh Berkus , Matthew Nuzum , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-21.8 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTE_TWICE_1, + USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/121 +X-Sequence-Number: 1627 + +On Thu, 10 Apr 2003, Ron Mayer wrote: + +> +> Short summary... +> +> I think sort_mem matters quite a bit (20-40%) on +> my data-warehousing applications. +> +> Am I doing something wrong to need so much sort_mem? + +No. In fact, it's not uncommon for certain queries to need WAY more sort +memory than most queries. The mistake that gets made is setting sort_mem +to something like 32 meg for every sort. There are many "sorts" on my +machine that are coming from well ordered data, and don't really need to +be done in memory to be reasonably fast. Those can run fine with 8 meg +sort_mem. For things with less well ordered in the database, or where the +data set is really big (100s of megs of data being sorted) it often helps +to just grab a 100 meg sort_mem for the session. + +If sort_mem is too big, the OS will likely wind up swapping it or shared +memory out and thrashing at the worst, or just surrendering all spare +memory to sort_mem, thus flushing all fs cache. For a lot of apps, it's +all about the sweet spot of memory to each subsystem, and sort_mem can go +from nibbling memory to eating it like Nibbler from Futurama in seconds if +you set it just a little too high and have the right parallel load on your +server. + +So, as long as you aren't starving your server of resources, setting +sort_mem higher is fine. + + +From pgsql-performance-owner@postgresql.org Fri Apr 11 12:16:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 587FD475F5F + for ; + Fri, 11 Apr 2003 12:16:20 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 5859F4762A2 + for ; + Fri, 11 Apr 2003 12:16:04 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2956889; Fri, 11 Apr 2003 09:15:57 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Ron Mayer" , "Matthew Nuzum" , + "'Pgsql-Performance'" +Subject: Re: Caching (was Re: choosing the right platform) +Date: Fri, 11 Apr 2003 09:15:15 -0700 +User-Agent: KMail/1.4.3 +Cc: +References: +In-Reply-To: +MIME-Version: 1.0 +Message-Id: <200304110915.15060.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/122 +X-Sequence-Number: 1628 + +Ron, + +> In a data warehouse we have here, we load about 3 million rows +> each week; load time improved from about 9 to 7 hours +> by breaking up such queries into expressions that only require +> one sort at a time, and surrounding the expressions with +> "set sort_mem=3Dsomething_big" statements to give it enough +> space to not hit the disk. +> +> SET SORT_MEM=3D300000; +> CREATE TEMPORARY TABLE potential_new_values AS +> SELECT DISTINCT val FROM import_table; +> ... +> SET SORT_MEM=3D1000; +> +> Anyone else have similar experience, or am I doing something +> wrong to need so much SORT_MEM? + +No, this sounds very reasonable to me. I do a similar operation on one of = +my=20 +systems as part of a nightly data transformation for reporting. Since I=20 +haven't had to do those on tables over 150,000 rows, I haven't seen the kin= +d=20 +of RAM usage you experience. + +> Below is an example of another real-world query from the same +> reporting system that benefits from a sort_mem over 32M. +> Explain analyze (below) shows a 40% improvement by having +> the sort fit in memory. + +Cool! That's a perfect example of sizing sort_mem for the query. Mind if= + I=20 +steal it for an article at some point? + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Fri Apr 11 13:38:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 56FD847644D + for ; + Fri, 11 Apr 2003 13:38:32 -0400 (EDT) +Received: from torque.intervideoinc.com (mail.intervideo.com + [206.112.112.151]) + by postgresql.org (Postfix) with ESMTP id 27E6147651D + for ; + Fri, 11 Apr 2003 13:33:48 -0400 (EDT) +Received: from ronpc [63.68.5.2] by torque.intervideoinc.com + (SMTPD32-5.05) id A13F233100F2; Fri, 11 Apr 2003 10:54:07 -0700 +From: "Ron Mayer" +To: "Josh Berkus" , "Matthew Nuzum" , + "'Pgsql-Performance'" +Cc: +Subject: Re: Caching (was Re: choosing the right platform) +Date: Fri, 11 Apr 2003 10:25:24 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 +Importance: Normal +In-Reply-To: <200304110915.15060.josh@agliodbs.com> +X-Spam-Status: No, hits=-14.8 required=5.0 + tests=BAYES_20,IN_REP_TO,MSGID_GOOD_EXCHANGE,QUOTED_EMAIL_TEXT, + SMTPD_IN_RCVD autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/123 +X-Sequence-Number: 1629 + + +Josh wrote: +>Ron, +>> Below is an example of another real-world query from the same +>> reporting system that benefits from a sort_mem over 32M. +>> Explain analyze (below) shows a 40% improvement by having +>> the sort fit in memory. +> +>Cool! That's a perfect example of sizing sort_mem for the query. Mind if I +>steal it for an article at some point? + +Gladly! + + +BTW... if you're writing a tuning article, the most interesting one +I've seen is: + http://otn.oracle.com/oramag/webcolumns/2002/techarticles/scalzo_linux01.html +I like how they broke down the process in many steps and measured after each. +I'm was intrigued by how much Linux's VM tweaking (vm.bdflush) affected +performance mattered as much at the more-commontly tweaked "noatime". + + Ron + + +From pgsql-performance-owner@postgresql.org Sat Apr 12 13:06:20 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 002F6475B85 + for ; + Sat, 12 Apr 2003 13:06:19 -0400 (EDT) +Received: from smtp-relay-3.sea.adobe.com (smtp-relay-3.adobe.com + [192.150.22.10]) + by postgresql.org (Postfix) with ESMTP id 321F2475AE4 + for ; + Sat, 12 Apr 2003 13:06:13 -0400 (EDT) +Received: from inner-relay-3.corp.adobe.com (inner-relay-3 [153.32.251.51]) + by smtp-relay-3.sea.adobe.com (8.12.9/8.12.9) with ESMTP id + h3CH67rT009475 for ; + Sat, 12 Apr 2003 10:06:13 -0700 (PDT) +Received: from mail-321.corp.adobe.com (mail-321 [153.32.2.46]) + by inner-relay-3.corp.adobe.com (8.12.3/8.12.3) with ESMTP id + h3CH67iQ028819 for ; + Sat, 12 Apr 2003 10:06:07 -0700 (PDT) +Received: from adobe.com (c-155-123.corp.adobe.com [153.32.155.123]) + by mail-321.corp.adobe.com (8.11.4/8.11.4) with ESMTP id h3CH4o922189 + for ; + Sat, 12 Apr 2003 10:04:50 -0700 (PDT) +Message-ID: <3E98498C.80306@adobe.com> +Date: Sat, 12 Apr 2003 10:14:52 -0700 +From: shane hill +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; + rv:1.0.0) Gecko/20020530 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance +Subject: update query blows out +References: <564664787.20030410102049@procedium.com> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-18.6 required=5.0 + tests=BAYES_10,REFERENCES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/124 +X-Sequence-Number: 1630 + +Hi folks, sorry if the following is confusing, I have just tried to +provide the pertinent info and I have been up for more than 24 hours +working. I am getting weary.... + +I am having a problem with an update transaction. I need to update 4000+ +records but the update query keeps blowing out postgres and at times I +am forced to restart the postmaster or reboot my server if I update +2500+ records. The query is fine with 2225 records it is just somewhere +beyond 2225 that brings the server down. + +I assumed this was related to the shared memory settings but when I +tried changing those values the behavior was identical. I did not try +beyond 256 megs for shmmax. +I then tried the temporary solution of lowering the number of +shared_buffers and max_connections but that did not change anything either. +I then tried using the IN operator but that did not change anything either + +I am wondering if there is some other limit that I am hitting in MacOSX +that is not related to the SHM vars. + +I hope I am just overlooking something simple and that the list will +come back with some chiding and an answer :) + +does anybody have any suggestions? + +thank you very much, + +-Shane + + +----------------------------------------------------------- +SQL DETAILS: + +my query is of this form: + +BEGIN; + +UPDATE "mytable" SET "n_filtered"=0,"n_dirty"=1 where ("s_fileName" = +'filename1' OR "s_fileName" = 'filename2' ....... OR "s_fileName" = +'filename2000') AND ("n_objId=12345); + +COMMIT; + +explain tells me this: + +seq scan on "mytable" (cost=0.00..5020.00 rows=5 width=174) Filter + ......... + +----------------------------------------------------------- + +----------------------------------------------------------- +SYSTEM: + +os: Mac 10.2.4 +chip: 1.4 GHz +ram: 1 GB +----------------------------------------------------------- + +----------------------------------------------------------- +ERROR MESSAGE: + +server process (pid 650) was terminated by signal 11 +all server processes terminated; reinitializing shared memopry and +semaphores + +----------------------------------------------------------- + +----------------------------------------------------------- +SOLUTIONS I HAVE TRIED + +1. tweaking the five kern.sysv vars. to every configurable option possible + +currently I am at: + +kern.sysv.shmmax: 1073741824 +kern.sysv.shmmin: 256 +kern.sysv.shmmni: 8192 +kern.sysv.shmseg: 2048 +kern.sysv.shmall: 262144 + +(I know shmmin is way too high according to the stuff I read, I was just +getting desperate, I have tried just leaving it at 1) + + +2. lowering the number of shared_buffers and max_connections to 32:16 +32:8 16:8 in postgresql.conf + +currently I am at 64 shared_bufs and 32 max_connects (these were the +defaults) + +3. Using the IN sql operator rather than a bunch of ORs, but I still +have the same problem + +------------------------------------- + + +From pgsql-performance-owner@postgresql.org Sat Apr 12 13:17:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D7A4E475AA9 + for ; + Sat, 12 Apr 2003 13:17:01 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 12A2347580B + for ; + Sat, 12 Apr 2003 13:17:01 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3CHGP2L018801; + Sat, 12 Apr 2003 13:16:25 -0400 (EDT) +To: shane hill +Cc: pgsql-performance +Subject: Re: update query blows out +In-reply-to: <3E98498C.80306@adobe.com> +References: <564664787.20030410102049@procedium.com> + <3E98498C.80306@adobe.com> +Comments: In-reply-to shane hill + message dated "Sat, 12 Apr 2003 10:14:52 -0700" +Date: Sat, 12 Apr 2003 13:16:24 -0400 +Message-ID: <18800.1050167784@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/125 +X-Sequence-Number: 1631 + +shane hill writes: +> I am having a problem with an update transaction. I need to update 4000+ +> records but the update query keeps blowing out postgres and at times I +> am forced to restart the postmaster or reboot my server if I update +> 2500+ records. The query is fine with 2225 records it is just somewhere +> beyond 2225 that brings the server down. + +What Postgres version? Can you get a backtrace from the core dump? + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sat Apr 12 14:06:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AE5C24762E1 + for ; + Sat, 12 Apr 2003 14:06:33 -0400 (EDT) +Received: from smtp-relay-3.sea.adobe.com (smtp-relay-3.adobe.com + [192.150.22.10]) + by postgresql.org (Postfix) with ESMTP id 2C04F47580B + for ; + Sat, 12 Apr 2003 14:06:31 -0400 (EDT) +Received: from inner-relay-3.corp.adobe.com (inner-relay-3 [153.32.251.51]) + by smtp-relay-3.sea.adobe.com (8.12.9/8.12.9) with ESMTP id + h3CI6LrT013974; Sat, 12 Apr 2003 11:06:27 -0700 (PDT) +Received: from mail-321.corp.adobe.com (mail-321 [153.32.2.46]) + by inner-relay-3.corp.adobe.com (8.12.3/8.12.3) with ESMTP id + h3CI6GiQ000739; Sat, 12 Apr 2003 11:06:16 -0700 (PDT) +Received: from adobe.com (c-155-123.corp.adobe.com [153.32.155.123]) + by mail-321.corp.adobe.com (8.11.4/8.11.4) with ESMTP id h3CI4r927796; + Sat, 12 Apr 2003 11:04:59 -0700 (PDT) +Message-ID: <3E98579F.8040904@adobe.com> +Date: Sat, 12 Apr 2003 11:14:55 -0700 +From: shane hill +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; + rv:1.0.0) Gecko/20020530 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane +Cc: pgsql-performance +Subject: Re: update query blows out +References: <564664787.20030410102049@procedium.com> + <3E98498C.80306@adobe.com> <18800.1050167784@sss.pgh.pa.us> +Content-Type: multipart/mixed; boundary="------------070800090800020601030107" +X-Spam-Status: No, hits=-25.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,REFERENCES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/126 +X-Sequence-Number: 1632 + +This is a multi-part message in MIME format. +--------------070800090800020601030107 +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit + +Postgres 7.3.1 + +The crash log is attached: + +thank you very much! + +-Shane + + +Tom Lane wrote: + +>shane hill writes: +> +> +>>I am having a problem with an update transaction. I need to update 4000+ +>>records but the update query keeps blowing out postgres and at times I +>>am forced to restart the postmaster or reboot my server if I update +>>2500+ records. The query is fine with 2225 records it is just somewhere +>>beyond 2225 that brings the server down. +>> +>> +> +>What Postgres version? Can you get a backtrace from the core dump? +> +> regards, tom lane +> +> +>---------------------------(end of broadcast)--------------------------- +>TIP 6: Have you searched our list archives? +> +>http://archives.postgresql.org +> +> +> +> + + + +--------------070800090800020601030107 +Content-Type: text/plain; + name="postmaster.crash.log" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline; + filename="postmaster.crash.log" + +Date/Time: 2003-04-11 22:44:26 -0700 +OS Version: 10.2.4 (Build 6I35) +Host: qesx + +Command: postmaster +PID: 622 + +Exception: EXC_BAD_ACCESS (0x0001) +Codes: KERN_INVALID_ADDRESS (0x0001) at 0xbff7ffc0 + +Thread 0 Crashed: + #0 0x000acb88 in eval_const_expressions_mutator (clauses.c:1130) + #1 0x000add34 in expression_tree_mutator (clauses.c:2314) + #2 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #3 0x000add34 in expression_tree_mutator (clauses.c:2314) + #4 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #5 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expression_tree_mutator (clauses.c:2314) + #488 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #489 0x000add34 in expression_tree_mutator (clauses.c:2314) + #490 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #491 0x000add34 in expression_tree_mutator (clauses.c:2314) + #492 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #493 0x000add34 in expression_tree_mutator (clauses.c:2314) + #494 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #495 0x000add34 in expression_tree_mutator (clauses.c:2314) + #496 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #497 0x000add34 in expression_tree_mutator (clauses.c:2314) + #498 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #499 0x000add34 in expression_tree_mutator (clauses.c:2314) + #500 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #501 0x000add34 in expression_tree_mutator (clauses.c:2314) + #502 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #503 0x000add34 in expression_tree_mutator (clauses.c:2314) + #504 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #505 0x000add34 in expression_tree_mutator (clauses.c:2314) + #506 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + #507 0x000add34 in expression_tree_mutator (clauses.c:2314) + #508 0x000acbb8 in eval_const_expressions_mutator (clauses.c:1149) + +PPC Thread State: + srr0: 0x000acb88 srr1: 0x0000d930 vrsave: 0x00000000 + xer: 0x20000000 lr: 0x000acb80 ctr: 0x000acb70 mq: 0x00000000 + r0: 0x000add34 r1: 0xbff80030 r2: 0x24024424 r3: 0x0157ff90 + r4: 0x00000000 r5: 0x000001f5 r6: 0x00001f40 r7: 0x0000000c + r8: 0x00000000 r9: 0x01202b18 r10: 0x00000000 r11: 0x00000000 + r12: 0x000acb70 r13: 0x001a0c30 r14: 0x00afa008 r15: 0xbfffee60 + r16: 0x00000002 r17: 0x00000001 r18: 0x001a2dd4 r19: 0x0019e9d0 + r20: 0x00000002 r21: 0x001a6f84 r22: 0x00000000 r23: 0x00000000 + r24: 0x001a6f84 r25: 0x00000000 r26: 0x000acb70 r27: 0x00000000 + r28: 0x0157ff90 r29: 0x01581130 r30: 0x00000000 r31: 0x000acb80 + + +--------------070800090800020601030107-- + + +From pgsql-performance-owner@postgresql.org Sat Apr 12 16:53:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4553C4762EF + for ; + Sat, 12 Apr 2003 16:53:43 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 886334762E1 + for ; + Sat, 12 Apr 2003 16:53:42 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3CKrN2L019652; + Sat, 12 Apr 2003 16:53:23 -0400 (EDT) +To: shane hill +Cc: pgsql-performance +Subject: Re: update query blows out +In-reply-to: <3E98579F.8040904@adobe.com> +References: <564664787.20030410102049@procedium.com> + <3E98498C.80306@adobe.com> <18800.1050167784@sss.pgh.pa.us> + <3E98579F.8040904@adobe.com> +Comments: In-reply-to shane hill + message dated "Sat, 12 Apr 2003 11:14:55 -0700" +Date: Sat, 12 Apr 2003 16:53:23 -0400 +Message-ID: <19651.1050180803@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/127 +X-Sequence-Number: 1633 + +shane hill writes: +> I am having a problem with an update transaction. I need to update 4000+ +> records but the update query keeps blowing out postgres and at times I +> am forced to restart the postmaster or reboot my server if I update +> 2500+ records. The query is fine with 2225 records it is just somewhere +> beyond 2225 that brings the server down. + +> [ core dump in heavily-recursive routine ] + +I think you are running into a stack-size problem. A quick look at +"ulimit -a" on my own OS X machine shows that the default stack limit +is a mere 512KB, which is verging on the ridiculously small :-(. + +Try setting "ulimit -s 10000" or so in the script that launches the +postmaster. Now that I look at it, the -d setting is on the miserly +side as well ... + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 13 21:45:06 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A64734760E3 + for ; + Sun, 13 Apr 2003 21:45:04 -0400 (EDT) +Received: from wolff.to (wolff.to [66.93.249.74]) + by postgresql.org (Postfix) with SMTP id ED07047580B + for ; + Sun, 13 Apr 2003 21:45:03 -0400 (EDT) +Received: (qmail 19493 invoked by uid 500); 14 Apr 2003 01:45:47 -0000 +Date: Sun, 13 Apr 2003 20:45:47 -0500 +From: Bruno Wolff III +To: pgsql-performance@postgresql.org +Subject: Multicolumn indexes and equal conditions +Message-ID: <20030414014547.GA19450@wolff.to> +Mail-Followup-To: pgsql-performance@postgresql.org +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.5.4i +X-Spam-Status: No, hits=-12.1 required=5.0 tests=BAYES_10,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/128 +X-Sequence-Number: 1634 + +I noticed that when a multicolumn index exists it isn't necessarily +fully used when the first column is constrained by an equals condition. +However by adding a redundant sort condition you can get both columns +used. + +In the following examples crate has an index on gameid and areaid. + +The examples below are for 7.4 development, but 7.3.2 behaves similarly. + +explain analyze select areaid from crate where gameid = 'TTN' order by areaid; + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------- + Sort (cost=132.93..133.02 rows=36 width=11) (actual time=5.44..5.57 rows=287 loops=1) + Sort Key: areaid + -> Index Scan using crate_game on crate (cost=0.00..132.00 rows=36 width=11) (actual time=0.06..1.94 rows=287 loops=1) + Index Cond: (gameid = 'TTN'::text) + Total runtime: 5.81 msec +(5 rows) + + +explain analyze select areaid from crate where gameid = 'TTN' order by gameid, areaid; + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------- + Index Scan using crate_game on crate (cost=0.00..132.00 rows=36 width=18) (actual time=0.08..2.06 rows=287 loops=1) + Index Cond: (gameid = 'TTN'::text) + Total runtime: 2.51 msec +(3 rows) + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 05:47:20 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 35CD2476349 + for ; + Tue, 15 Apr 2003 05:47:19 -0400 (EDT) +Received: from shsis (unknown [211.102.12.252]) + by postgresql.org (Postfix) with ESMTP id 28FC4474E44 + for ; + Tue, 15 Apr 2003 05:46:55 -0400 (EDT) +Received: from linweidong (localhost [127.0.0.1]) + by shsis.sis.sh.cn (iPlanet Messaging Server 5.1 (built May 7 2001)) + with ESMTPA id <0HDD00MKCPSXWX@shsis.sis.sh.cn> for + pgsql-performance@postgresql.org; Tue, 15 Apr 2003 17:46:09 +0800 (CST) +Date: Tue, 15 Apr 2003 17:44:44 +0800 +From: linweidong +Subject: for help! +To: pgsql-performance@postgresql.org +Message-id: <000901c30333$a52b7550$3c10a9c0@jinrong.sis.sh.cn> +MIME-version: 1.0 +X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +Content-type: multipart/alternative; + boundary="Boundary_(ID_Ey6rZIIpjMasACNrZ7e5XQ)" +X-Priority: 3 +X-MSMail-priority: Normal +X-Spam-Status: No, hits=-1.8 required=5.0 + tests=BAYES_20,HTML_60_70,RCVD_IN_OSIRUSOFT_COM,SATISFACTION + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/129 +X-Sequence-Number: 1635 + + +This is a multi-part message in MIME format. + +--Boundary_(ID_Ey6rZIIpjMasACNrZ7e5XQ) +Content-type: text/plain; charset=iso-2022-jp +Content-transfer-encoding: 7BIT + +Hi, + + + + I am writing to you to discuss the performance problem of postgreSQL +database we encountered in our project. I want to get suggestions from you. + + + +The postgreSQL database we used need to process several millions records. +There are only six tables in the database. one of them contains several +million records, the Others are less smaller. We need select more than 100 +thousands records from the talbe which contains several million records in +10 seconds. In the process of selecting, the speed of selecting is not +stable. Sometimes it cost 2 minutes , but sometimes 20 seconds. After +analyzing the time wasting in the process, we found the speed of function +Count(*) is very slow. At the same time we have finished the setup of some +parameters like max_fsm_relation, max_fsm_pages, share memory size etc, but +the performance is not improved satisfied. + + + +Under this condition, I want get some useful suggestion from you. How to +optimize the database? How to improve the Count(*)? Because we want to get +the number of records in the recordset we got. + + + +Thank you every much! I hope hear from you soon. + + +Wind + + +2003-4-15 + +--Boundary_(ID_Ey6rZIIpjMasACNrZ7e5XQ) +Content-type: text/html; charset=iso-2022-jp +Content-transfer-encoding: 7BIT + + + + + + + + +
+

Hi,

+

 

+

 I am writing +to you to discuss the performance problem of postgreSQL database we encountered +in our project. I + want to get suggestions from +you.

+

 

+

The postgreSQL database we used need to process several +millions records. There are only six tables in the database. one of them +contains several +million records, +the  Others are less +smaller. We need +select more than 100 thousands records from the talbe which contains several +million records in 10 seconds.  +In the process of selecting, the speed of selecting is not stable. +Sometimes it cost 2 minutes , but sometimes 20 seconds. After analyzing the time +wasting in the process, we found the speed of  function Count(*) is very slow. At the +same time we have finished the setup of some parameters like max_fsm_relation, +max_fsm_pages, share memory size etc, but the performance is not improved +satisfied.

+

 

+

Under this condition, I want get some useful +suggestion from you. How to optimize the database?  How to improve the Count(*)? Because +we  want to get the number of +records in the recordset  we +got.

+

  +

+

Thank you every much! I hope hear from you +soon.

+

                                                                                                 +Wind

+

                                                                  +                                    2003-4-15 +

+ +--Boundary_(ID_Ey6rZIIpjMasACNrZ7e5XQ)-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 05:54:07 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9E4B847633C + for ; + Tue, 15 Apr 2003 05:54:06 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 9C3F0475F1C + for ; + Tue, 15 Apr 2003 05:54:04 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h3F9s6J20564 + for ; Tue, 15 Apr 2003 15:24:06 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h3F9s5220559 + for ; Tue, 15 Apr 2003 15:24:05 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: Re: for help! +Date: Tue, 15 Apr 2003 15:24:11 +0530 +User-Agent: KMail/1.5 +References: <000901c30333$a52b7550$3c10a9c0@jinrong.sis.sh.cn> +In-Reply-To: <000901c30333$a52b7550$3c10a9c0@jinrong.sis.sh.cn> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-2022-jp" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304151524.11721.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-31.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SATISFACTION,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/130 +X-Sequence-Number: 1636 + +On Tuesday 15 April 2003 15:14, you wrote: +> The postgreSQL database we used need to process several millions records. +> There are only six tables in the database. one of them contains several +> million records, the Others are less smaller. We need select more than 100 +> thousands records from the talbe which contains several million records in +> 10 seconds. In the process of selecting, the speed of selecting is not +> stable. Sometimes it cost 2 minutes , but sometimes 20 seconds. After +> analyzing the time wasting in the process, we found the speed of function +> Count(*) is very slow. At the same time we have finished the setup of some +> parameters like max_fsm_relation, max_fsm_pages, share memory size etc, but +> the performance is not improved satisfied. + +Why do you need to do select count(*) to select more than 100 thousand +records? + +Postgresql being MVCC database, select count(*) is not going to be anywhere +near good, especially if you have transactions occuring on table. + +As far as just selecting rows from table, that should be tad fast if there are +proper indexes, table in analyzed every now and then and there are enough +shared buffers. + +If you post your queries and table schemas, that would be much helpful. Your +tweaked settings in postgresql.conf and hardware spec. would be good as well. + +> Under this condition, I want get some useful suggestion from you. How to +> optimize the database? How to improve the Count(*)? Because we want to +> get the number of records in the recordset we got. + +If you are using say libpq, you don't need to issue a select count(*) where +foo and select where foo, to obtain record count and the records themselves. +I believe every other interface stemming from libpq should provide any such +hooks as well. Never used any other myself (barring ecpg) + + HTH + + Shridhar + + +From pgsql-general-owner@postgresql.org Tue Apr 15 10:23:45 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 8DBDE474E44; Tue, 15 Apr 2003 10:23:42 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id AB4F34758F1; Tue, 15 Apr 2003 10:23:37 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id h3FENUf06986; + Tue, 15 Apr 2003 10:23:30 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200304151423.h3FENUf06986@candle.pha.pa.us> +Subject: Re: [PERFORM] Yet Another (Simple) Case of Index not used +In-Reply-To: <3E93348C.20208@cvc.net> +To: gearond@cvc.net +Date: Tue, 15 Apr 2003 10:23:30 -0400 (EDT) +Cc: Dann Corbit , Denis , + pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/886 +X-Sequence-Number: 40951 + +Dennis Gearon wrote: +> from mysql manual: +> ------------------------------------------------------------- +> "COUNT(*) is optimized to return very quickly if the SELECT retrieves from one +> table, no other columns are retrieved, and there is no WHERE clause. For example: +> +> mysql> select COUNT(*) from student;" +> ------------------------------------------------------------- +> +> A nice little optimization, maybe not possible in a MVCC system. + +I think the only thing you can do with MVCC is to cache the value and +tranaction id for "SELECT AGG(*) FROM tab" and make the cached value +visible to transaction id's greater than the one that executed the +query, and invalidate the cache every time the table is modified. + +In fact, don't clear the cache, just record the transaction id of the +table modification command so we can use standard visibility routines to +make the cache usable as long as possiible. + +The cleanest way would probably be to create an aggregate cache system +table, and to insert into it when someone does an unqualified aggregate, +and to delete from it when someone modifies the table --- the MVCC tuple +visibility rules are handled automatically. Queries can look in there +to see if a visible cached value already exists. Of course, the big +question is whether this would be a big win, and whether the cost of +upkeep would justify it. + +-- + Bruce Momjian | http://candle.pha.pa.us + pgman@candle.pha.pa.us | (610) 359-1001 + + If your life is a hard drive, | 13 Roberts Road + + Christ can be your backup. | Newtown Square, Pennsylvania 19073 + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 11:40:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 58523475A80 + for ; + Tue, 15 Apr 2003 11:40:03 -0400 (EDT) +Received: from isis.pcis.net (cr.pcis.net [207.18.226.3]) + by postgresql.org (Postfix) with ESMTP id DB5A3474E44 + for ; + Tue, 15 Apr 2003 11:40:01 -0400 (EDT) +Received: from lyric.ofsloans.com (unverified [209.180.142.225]) by + isis.pcis.net + (Rockliffe SMTPRA 4.5.6) with ESMTP id ; + Tue, 15 Apr 2003 10:40:11 -0500 +Subject: Re: for help! +From: Will LaShell +To: Shridhar Daithankar +Cc: pgsql-performance@postgresql.org +In-Reply-To: <200304151524.11721.shridhar_daithankar@nospam.persistent.co.in> +References: <000901c30333$a52b7550$3c10a9c0@jinrong.sis.sh.cn> + <200304151524.11721.shridhar_daithankar@nospam.persistent.co.in> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-UbhYXUzDSQc081K5WCyV" +X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) +Date: 15 Apr 2003 08:40:05 -0700 +Message-Id: <1050421206.25390.16.camel@lyric.ofsloans.com> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-28.1 required=5.0 + tests=BAYES_10,IN_REP_TO,PGP_SIGNATURE_2,REFERENCES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/132 +X-Sequence-Number: 1638 + +--=-UbhYXUzDSQc081K5WCyV +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + + +> > Under this condition, I want get some useful suggestion from you. How to +> > optimize the database? How to improve the Count(*)? Because we want to +> > get the number of records in the recordset we got. +>=20 +> If you are using say libpq, you don't need to issue a select count(*) whe= +re=20 +> foo and select where foo, to obtain record count and the records themselv= +es.=20 +> I believe every other interface stemming from libpq should provide any su= +ch=20 +> hooks as well. Never used any other myself (barring ecpg) + +The python interfaces most definitely do. Doing the count is quite +unnecessary just as Shridhar points out. + +> HTH +>=20 +> Shridhar +>=20 + +--=-UbhYXUzDSQc081K5WCyV +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.7 (GNU/Linux) + +iD8DBQA+nCfVZr3R5kgOZd0RAvZ6AJ9+P+AyG5dHJOgeqZiFlMdcHoJcMgCgiFjf +ofi+x2dMuVC+Fjr+5qCctw4= +=T1tv +-----END PGP SIGNATURE----- + +--=-UbhYXUzDSQc081K5WCyV-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 11:49:17 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 02256475A80 + for ; + Tue, 15 Apr 2003 11:49:16 -0400 (EDT) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id C3B77474E44 + for ; + Tue, 15 Apr 2003 11:49:14 -0400 (EDT) +Received: (qmail 13965 invoked from network); 15 Apr 2003 15:49:18 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 15 Apr 2003 15:49:18 -0000 +From: "Robert John Shepherd" +To: +Subject: Do Views offer any performance advantage? +Date: Tue, 15 Apr 2003 16:49:18 +0100 +Message-ID: <001f01c30366$93427720$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="US-ASCII" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-1.6 required=5.0 + tests=BAYES_30 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/133 +X-Sequence-Number: 1639 + +Hi all, + +Whilst I often use views for convenience, is there any performance +advantage at all in using a view rather than running the same query +directly on the tables themselves? + +Is it quicker to run a full complex query rather than run a much simpler +query on a view? (Hope that makes sense) + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-general-owner@postgresql.org Tue Apr 15 12:29:39 2003 +X-Original-To: pgsql-general@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 017F5476237; Tue, 15 Apr 2003 12:29:38 -0400 (EDT) +Received: from anchor-post-32.mail.demon.net (anchor-post-32.mail.demon.net + [194.217.242.90]) by postgresql.org (Postfix) with ESMTP + id 0F39F4758F1; Tue, 15 Apr 2003 12:29:37 -0400 (EDT) +Received: from mwynhau.demon.co.uk ([193.237.186.96] + helo=mainbox.archonet.com) + by anchor-post-32.mail.demon.net with esmtp (Exim 3.35 #1) + id 195TJV-0005Iu-0W; Tue, 15 Apr 2003 17:29:41 +0100 +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP + id 1198B176C4; Tue, 15 Apr 2003 17:29:40 +0100 (BST) +Received: from client.archonet.com (client.archonet.com [192.168.1.16]) + by mainbox.archonet.com (Postfix) with ESMTP + id 6BAFB176BB; Tue, 15 Apr 2003 17:29:39 +0100 (BST) +Content-Type: text/plain; + charset="iso-8859-1" +From: Richard Huxton +Organization: Archonet Ltd +To: Bruce Momjian , gearond@cvc.net +Subject: Re: [PERFORM] Yet Another (Simple) Case of Index not used +Date: Tue, 15 Apr 2003 17:29:45 +0100 +User-Agent: KMail/1.4.3 +Cc: Dann Corbit , Denis , + pgsql-performance@postgresql.org, pgsql-general@postgresql.org, + pgsql-sql@postgresql.org +References: <200304151423.h3FENUf06986@candle.pha.pa.us> +In-Reply-To: <200304151423.h3FENUf06986@candle.pha.pa.us> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304151729.45657.dev@archonet.com> +X-Virus-Scanned: by AMaViS snapshot-20020531 +X-Spam-Status: No, hits=-38.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/893 +X-Sequence-Number: 40958 + +On Tuesday 15 Apr 2003 3:23 pm, Bruce Momjian wrote: +> Dennis Gearon wrote: +> > from mysql manual: +> > ------------------------------------------------------------- +> > "COUNT(*) is optimized to return very quickly if the SELECT retrieves +> > from one table, no other columns are retrieved, and there is no WHERE +> > clause. For example: +> > +> > mysql> select COUNT(*) from student;" +> > ------------------------------------------------------------- + +> The cleanest way would probably be to create an aggregate cache system +> table, and to insert into it when someone does an unqualified aggregate, +> and to delete from it when someone modifies the table --- the MVCC tuple +> visibility rules are handled automatically. Queries can look in there +> to see if a visible cached value already exists. Of course, the big +> question is whether this would be a big win, and whether the cost of +> upkeep would justify it. + +If the rule system could handle something like: + +CREATE RULE quick_foo_count AS ON SELECT count(*) FROM foo=20 +DO INSTEAD +SELECT quick_count FROM agg_cache WHERE tbl_name=3D'foo'; + +The whole thing could be handled by user-space triggers/rules and still=20 +invisible to the end-user. + +--=20 + Richard Huxton + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 12:39:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 055D8474E44 + for ; + Tue, 15 Apr 2003 12:39:21 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 4E82D476348 + for ; + Tue, 15 Apr 2003 12:39:19 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3FGd1lo006538; + Tue, 15 Apr 2003 10:39:02 -0600 (MDT) +Date: Tue, 15 Apr 2003 10:34:21 -0600 (MDT) +From: "scott.marlowe" +To: linweidong +Cc: +Subject: Re: for help! +In-Reply-To: <000901c30333$a52b7550$3c10a9c0@jinrong.sis.sh.cn> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/135 +X-Sequence-Number: 1641 + +On Tue, 15 Apr 2003, linweidong wrote: + +> Under this condition, I want get some useful suggestion from you. How to +> optimize the database? How to improve the Count(*)? Because we want to get +> the number of records in the recordset we got. + +Well, you can always use the trick of putting an on insert / delete +trigger on the table that maintains a single row table with the current +count. That way, whenever a row is added or removed, the count is +updated. this will slow down inserts and deletes a little, but TANSTAAFL. + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 13:26:26 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B394F476347 + for ; + Tue, 15 Apr 2003 13:26:24 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id D5CBB476342 + for ; + Tue, 15 Apr 2003 13:26:23 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3FHQNU6008833; + Tue, 15 Apr 2003 13:26:23 -0400 (EDT) +To: "Robert John Shepherd" +Cc: pgsql-performance@postgresql.org +Subject: Re: Do Views offer any performance advantage? +In-reply-to: <001f01c30366$93427720$f3b0313e@LAIKA> +References: <001f01c30366$93427720$f3b0313e@LAIKA> +Comments: In-reply-to "Robert John Shepherd" + message dated "Tue, 15 Apr 2003 16:49:18 +0100" +Date: Tue, 15 Apr 2003 13:26:23 -0400 +Message-ID: <8832.1050427583@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/136 +X-Sequence-Number: 1642 + +"Robert John Shepherd" writes: +> Whilst I often use views for convenience, is there any performance +> advantage at all in using a view rather than running the same query +> directly on the tables themselves? + +No, a view is just a macro. + +There is probably some minuscule cost difference involved --- you save +parsing and parse analysis of a long query string. On the other hand, +you pay to pull the view definition from the catalogs and merge it into +the given query. I'd not care to hazard a guess on whether the actual +net cost is more or less; but in any case these costs will be swamped +by query planning and execution, if the query is complex. + +If you're concerned about reducing parse/plan overhead for repetitive +queries, the prepared-statement facility (new in 7.3) is what to look +at. Views won't do much for you. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 15:05:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BC9F147633C + for ; + Tue, 15 Apr 2003 15:05:20 -0400 (EDT) +Received: from sabre.velocet.net (sabre.velocet.net [216.138.209.205]) + by postgresql.org (Postfix) with ESMTP id 02512476333 + for ; + Tue, 15 Apr 2003 15:05:20 -0400 (EDT) +Received: from stark.dyndns.tv (H162.C233.tor.velocet.net [216.138.233.162]) + by sabre.velocet.net (Postfix) with ESMTP + id BB74513832C; Tue, 15 Apr 2003 15:04:14 -0400 (EDT) +Received: from localhost ([127.0.0.1] helo=stark.dyndns.tv ident=foobar) + by stark.dyndns.tv with smtp (Exim 3.36 #1 (Debian)) + id 195Viw-0005Er-00; Tue, 15 Apr 2003 15:04:06 -0400 +To: pgsql-performance@postgresql.org +Subject: Using indexes for like foo% type queries when foo isn't constant (not + a locale issue) +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 15 Apr 2003 15:04:04 -0400 +Message-ID: <87of37oa57.fsf@stark.dyndns.tv> +Lines: 41 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-12.9 required=5.0 tests=BAYES_01,USER_AGENT_GNUS_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/137 +X-Sequence-Number: 1643 + + +In the following query postgres doesn't use the index. In the hard-coded +version below it does. I suppose it can't because it's possible the "target" +could have wildcards etc in them. Is there any way to indicate the postgres +that that won't happen? + +This is going to be even more of an issue when preparsed queries happen +because even in the hard coded example it will be an issue. I know in Oracle +if you parse a query with a LIKE :1||'%' type expression it still plans to use +the index and that's extremely useful. I don't know what it does if there's a +% in the parameter, it either takes the performance hit or it doesn't treat +them as special? + +db=> explain analyze select postalcode, abs(substr(target,6,1)::integer-substr(postalcode,6,1)::integer) as dist from postalcodes, (select 'L6C2M6'::text as target) as t where postalcode like substr(target,1,5)||'%' order by dist asc limit 2; + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------- + Limit (cost=12182.77..12182.77 rows=2 width=42) (actual time=9226.17..9226.18 rows=2 loops=1) + -> Sort (cost=12182.77..12186.16 rows=1359 width=42) (actual time=9226.16..9226.16 rows=2 loops=1) + Sort Key: abs(((substr(t.target, 6, 1))::integer - (substr((postalcodes.postalcode)::text, 6, 1))::integer)) + -> Nested Loop (cost=0.00..12112.04 rows=1359 width=42) (actual time=3262.89..9205.25 rows=8 loops=1) + Join Filter: ("inner".postalcode ~~ (substr("outer".target, 1, 5) || '%'::text)) + -> Subquery Scan t (cost=0.00..0.01 rows=1 width=0) (actual time=0.04..0.05 rows=1 loops=1) + -> Result (cost=0.00..0.01 rows=1 width=0) (actual time=0.02..0.02 rows=1 loops=1) + -> Seq Scan on postalcodes (cost=0.00..7335.69 rows=271769 width=10) (actual time=5.52..3268.74 rows=271769 loops=1) + Total runtime: 9241.92 msec +(9 rows) + +db=> explain analyze select postalcode, abs(substr('L6C2M6',6,1)::integer-substr(postalcode,6,1)::integer) as dist from postalcodes where postalcode like substr('L6C2M6',1,5)||'%' order by dist asc limit 2; + QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------------------- + Limit (cost=3.29..3.29 rows=1 width=10) (actual time=36.54..36.55 rows=2 loops=1) + -> Sort (cost=3.29..3.29 rows=1 width=10) (actual time=36.53..36.54 rows=2 loops=1) + Sort Key: abs((6 - (substr((postalcode)::text, 6, 1))::integer)) + -> Index Scan using idx_postalcodes_postalcodeon on postalcodes (cost=0.00..3.28 rows=1 width=10) (actual time=35.91..36.33 rows=8 loops=1) + Index Cond: ((postalcode >= 'L6C2M'::bpchar) AND (postalcode < 'L6C2N'::bpchar)) + Filter: (postalcode ~~ 'L6C2M%'::text) + Total runtime: 36.93 msec +(7 rows) + +-- +greg + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 15:55:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DD3D847633C + for ; + Tue, 15 Apr 2003 15:55:13 -0400 (EDT) +Received: from smtp.web.de (smtp02.web.de [217.72.192.151]) + by postgresql.org (Postfix) with ESMTP id DFF29474E44 + for ; + Tue, 15 Apr 2003 15:55:08 -0400 (EDT) +Received: from p508188a2.dip0.t-ipconnect.de ([80.129.136.162] helo=web.de) + by smtp.web.de with asmtp (TLSv1:RC4-MD5:128) (WEB.DE(Exim) 4.97 #53) + id 195WWH-0000Sl-00 + for pgsql-performance@postgresql.org; Tue, 15 Apr 2003 21:55:05 +0200 +Message-ID: <3E9C63A8.4040801@web.de> +Date: Tue, 15 Apr 2003 21:55:20 +0200 +From: Andreas Pflug +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: Do Views offer any performance advantage? +References: <001f01c30366$93427720$f3b0313e@LAIKA> + <8832.1050427583@sss.pgh.pa.us> +In-Reply-To: <8832.1050427583@sss.pgh.pa.us> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-34.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,RCVD_IN_NJABL, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/138 +X-Sequence-Number: 1644 + +Tom Lane wrote: + +> +>There is probably some minuscule cost difference involved --- you save +>parsing and parse analysis of a long query string. On the other hand, +>you pay to pull the view definition from the catalogs and merge it into +>the given query. I'd not care to hazard a guess on whether the actual +>net cost is more or less; but in any case these costs will be swamped +>by query planning and execution, if the query is complex. +> +Actually, there are cases when a view can impact performance. +If you are joining a view, it seems to be treated as a subquery, that +might have a much larger result than you would like. + +Imagine +SELECT something + FROM A JOIN B JOIN C ... + WHERE A.primaryKeyFoo=1234 ... + + where C is a view, containing JOINs itself, I observed a query plan +(7.3.2) like +A JOIN B JOIN (D JOIN E) +instead of +A JOIN B JOIN D JOIN E which would be much more efficient for the +A.primaryKeyFoo restriction. + + +From pgsql-performance-owner@postgresql.org Tue Apr 15 19:37:05 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9DD65475458 + for ; + Tue, 15 Apr 2003 19:37:04 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 036AA474E44 + for ; + Tue, 15 Apr 2003 19:37:04 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3FNb6U6011036; + Tue, 15 Apr 2003 19:37:06 -0400 (EDT) +To: Andreas Pflug +Cc: pgsql-performance@postgresql.org +Subject: Re: Do Views offer any performance advantage? +In-reply-to: <3E9C63A8.4040801@web.de> +References: <001f01c30366$93427720$f3b0313e@LAIKA> + <8832.1050427583@sss.pgh.pa.us> <3E9C63A8.4040801@web.de> +Comments: In-reply-to Andreas Pflug + message dated "Tue, 15 Apr 2003 21:55:20 +0200" +Date: Tue, 15 Apr 2003 19:37:06 -0400 +Message-ID: <11035.1050449826@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/139 +X-Sequence-Number: 1645 + +Andreas Pflug writes: +> Actually, there are cases when a view can impact performance. +> If you are joining a view, it seems to be treated as a subquery, that +> might have a much larger result than you would like. + +> Imagine +> SELECT something +> FROM A JOIN B JOIN C ... +> WHERE A.primaryKeyFoo=1234 ... + +> where C is a view, containing JOINs itself, I observed a query plan +> (7.3.2) like +> A JOIN B JOIN (D JOIN E) +> instead of +> A JOIN B JOIN D JOIN E which would be much more efficient for the +> A.primaryKeyFoo restriction. + +This is not the view's fault though --- the same would have happened +if you'd written explicitly + + FROM A JOIN B JOIN (D JOIN E) + +7.4 will be less rigid about this (with or without a view ...) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 02:10:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 56600475A45 + for ; + Wed, 16 Apr 2003 02:10:44 -0400 (EDT) +Received: from smtp.kocks.com (adsl-66-124-90-234.dsl.snfc21.pacbell.net + [66.124.90.234]) + by postgresql.org (Postfix) with ESMTP id 88D8447592C + for ; + Wed, 16 Apr 2003 02:10:43 -0400 (EDT) +Received: from GARP (fwinside.kocks.com [10.10.10.1]) + by smtp.kocks.com (mail) with SMTP id C328A28AC3 + for ; + Tue, 15 Apr 2003 23:10:43 -0700 (PDT) +Reply-To: +From: "dex" +To: +Subject: Is there a performance between Inherits and Views? +Date: Tue, 15 Apr 2003 23:10:44 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-7.3 required=5.0 tests=BAYES_30,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/140 +X-Sequence-Number: 1646 + +Hello, + +In building a schema, I'd like to know if it makes sense +from a performance standpoint to use views instead of +an object oriented structure (i.e. inherits). + +I would guess that the overhead of the queries against +inherited tables is higher than queries against views, +but I don't know. + +In the cities / capitals example below, I could make +queries such as: + +SELECT name FROM capitals; + +or + +SELECT name FROM capital_cities; + +But which one would be faster? In my real world example, +I will have one small base object table (i.e. cities in +the example) and many direct descendents of that base +table (e.g. capitals, beaches, national parks, suburbs +in the example). This could be implemented as one +small base table and with many tables inheriting from +the base. Or, it could be implemented as one larger +(but not huge) lookup table with many views. + +What's the better choice from a performance standpoint? + +Thanks! + +--dex + + +-- +-- Schema with Inherits +-- +CREATE TABLE cities ( + name text, + population float, + altitude int -- (in ft) + ); + + CREATE TABLE capitals ( + state char(2) + ) INHERITS (cities); + + +-- +-- Schema with View +-- +CREATE TABLE all_cities ( + name text, + population float, + altitude int, + state char(2) +); + +CREATE VIEW just_cities AS SELECT + all_cities.name, + all_cities.population, + all_cities.altitude +FROM all_cities; + +-- or perhaps with a where clause, as in +CREATE VIEW capital_cities AS SELECT + all_cities.name, + all_cities.population, + all_cities.altitude +FROM all_cities WHERE (all_cities.state IS NOT NULL); + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 20:03:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 59E43475EEE + for ; + Wed, 16 Apr 2003 20:03:08 -0400 (EDT) +Received: from spunge-bob.discern.com (moore.discerncomm.com [130.107.25.153]) + by postgresql.org (Postfix) with ESMTP id 79792475ECE + for ; + Wed, 16 Apr 2003 20:03:07 -0400 (EDT) +Received: by spunge-bob.discern.com (Postfix, from userid 1000) + id 4CA5B27C88; Tue, 15 Apr 2003 23:58:28 -0700 (PDT) +Subject: dum query plan +From: Jonathan Moore +To: pgsql-performance@postgresql.org +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.5 +Date: 15 Apr 2003 23:58:28 -0700 +Message-Id: <1050476308.20872.19.camel@spunge-bob> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-12.0 required=5.0 + tests=BAYES_10,DATE_IN_PAST_12_24,USER_AGENT_XIMIAN + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/147 +X-Sequence-Number: 1653 + +I am wondering why it uses the O(n^2) nested loop when there is a O(N) +methoud using btree indexes for a merg join. I am using 7.2.1 would +upgrading fix my problime or is it somthing else? + +Given the schema: + +drop table Entry_Pairs; +create table Entry_Pairs ( + left_entry int REFERENCES Entry ON DELETE RESTRICT, + right_entry int REFERENCES Entry ON DELETE RESTRICT, + relation int NOT NULL , + subtract bool NOT NULL , + comment int NULL REFERENCES Comment ON DELETE SET NULL, + UNIQUE (left_entry, right_entry, relation) +); +CREATE INDEX entry_pairs_left_index ON entry_pairs (left_entry); +CREATE INDEX entry_pairs_right_index ON entry_pairs (right_entry); +-- + +You get this" + +dblex=> explain select A.left_entry from entry_pairs A, entry_pairs B +where A.right_entry != B.left_entry; +NOTICE: QUERY PLAN: + +Nested Loop (cost=100000000.00..102876671.17 rows=97545252 width=12) + -> Seq Scan on entry_pairs a (cost=0.00..167.77 rows=9877 width=8) + -> Seq Scan on entry_pairs b (cost=0.00..167.77 rows=9877 width=4) + +EXPLAIN + +That is dum. If you just walk both B-Tree indexes there is a O(n) +search. I tryed to turn off netsed loops but it still did it. (the +reason the cost is 100000000.00 is a artifact from turing off loops) + +-Jonathan + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 04:45:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EF2904758F1 + for ; + Wed, 16 Apr 2003 04:45:41 -0400 (EDT) +Received: from smtp.web.de (smtp01.web.de [217.72.192.180]) + by postgresql.org (Postfix) with ESMTP id 89CD8475458 + for ; + Wed, 16 Apr 2003 04:45:10 -0400 (EDT) +Received: from p50818648.dip0.t-ipconnect.de ([80.129.134.72] helo=web.de) + by smtp.web.de with asmtp (TLSv1:RC4-MD5:128) (WEB.DE(Exim) 4.97 #53) + id 195iXQ-0002uG-00; Wed, 16 Apr 2003 10:45:04 +0200 +Message-ID: <3E9D1820.6000100@web.de> +Date: Wed, 16 Apr 2003 10:45:20 +0200 +From: Andreas Pflug +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: Do Views offer any performance advantage? +References: <001f01c30366$93427720$f3b0313e@LAIKA> + <8832.1050427583@sss.pgh.pa.us> <3E9C63A8.4040801@web.de> + <11035.1050449826@sss.pgh.pa.us> +In-Reply-To: <11035.1050449826@sss.pgh.pa.us> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-34.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,RCVD_IN_NJABL, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/141 +X-Sequence-Number: 1647 + +Tom Lane wrote: + +>This is not the view's fault though --- the same would have happened +>if you'd written explicitly +> +> FROM A JOIN B JOIN (D JOIN E) +> +That's right, I just wanted to warn about accessive use of joins with +views. I noticed this in an application, where quite big views where +joined for convenience, and the result wasn't satisfying. + +> +>7.4 will be less rigid about this (with or without a view ...) +> +Good! +Regards, +Andreas + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 11:48:53 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 64D96475C3D + for ; + Wed, 16 Apr 2003 11:48:52 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 9118F475C15 + for ; + Wed, 16 Apr 2003 11:48:51 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2967362; Wed, 16 Apr 2003 08:48:49 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "scott.marlowe" , + linweidong +Subject: Re: for help! +Date: Wed, 16 Apr 2003 08:48:36 -0700 +User-Agent: KMail/1.4.3 +Cc: +References: +In-Reply-To: +MIME-Version: 1.0 +Message-Id: <200304160848.36431.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/142 +X-Sequence-Number: 1648 + +Scott, + +> Well, you can always use the trick of putting an on insert / delete +> trigger on the table that maintains a single row table with the current +> count. That way, whenever a row is added or removed, the count is +> updated. this will slow down inserts and deletes a little, but TANSTAAFL. + +BTW, I tested this for a client. I found the performance penalty on inser= +ts=20 +and updates to be: + +-- For a single stream of intermittent updates from a single connection + on an adequately powered server with moderate disk support (IDE Linux RA= +ID) + (100 inserts/updates per minute, with VACUUM every 5 minutes) + PL/pgSQL Trigger: 20% penalty C Trigger: 9-11% penalty + +-- For 5 streams of inserts and updates at high volume on an overloaded + server with moderate disk support (dual fast SCSI disks) + (1000 inserts/updates per minute, vacuum every 5 minutes) + PL/pgSQL Trigger: 65% penalty C Trigger: 40% penalty + +Please note that the effective performance penalty on inserts and updates w= +as=20 +dramatically higher for large batches of updates than for small ones. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 11:53:15 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E2CF6476304 + for ; + Wed, 16 Apr 2003 11:53:12 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 2674F476302 + for ; + Wed, 16 Apr 2003 11:53:07 -0400 (EDT) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 195pDk-0002Ot-00 + for ; Wed, 16 Apr 2003 11:53:12 -0400 +Received: by dba2 (Postfix, from userid 1019) + id 60732CF00; Wed, 16 Apr 2003 11:53:12 -0400 (EDT) +Date: Wed, 16 Apr 2003 11:53:12 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: for help! +Message-ID: <20030416155312.GF19999@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: + <200304160848.36431.josh@agliodbs.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <200304160848.36431.josh@agliodbs.com> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/143 +X-Sequence-Number: 1649 + +On Wed, Apr 16, 2003 at 08:48:36AM -0700, Josh Berkus wrote: +> Scott, +> +> > Well, you can always use the trick of putting an on insert / delete +> > trigger on the table that maintains a single row table with the current +> > count. That way, whenever a row is added or removed, the count is + +> BTW, I tested this for a client. I found the performance penalty +> on inserts and updates to be: + +[. . .] + +> Please note that the effective performance penalty on inserts and +> updates was dramatically higher for large batches of updates than +> for small ones. + +Presumably the problem was to do with contention? This is why I +don't really like the "update one row" approach for this sort of +thing. + +But you _could_ write a trigger which inserts into a "staging" table, +and write a little daemon which only updates the count table with the +data from the staging table. It's a mighty ugly hack, but it ought +to work. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 12:01:53 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B3D11475A45 + for ; + Wed, 16 Apr 2003 12:01:52 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id F24CE475458 + for ; + Wed, 16 Apr 2003 12:01:51 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3GG1uU6018665; + Wed, 16 Apr 2003 12:01:56 -0400 (EDT) +To: Andrew Sullivan +Cc: pgsql-performance@postgresql.org +Subject: Re: for help! +In-reply-to: <20030416155312.GF19999@libertyrms.info> +References: + <200304160848.36431.josh@agliodbs.com> + <20030416155312.GF19999@libertyrms.info> +Comments: In-reply-to Andrew Sullivan + message dated "Wed, 16 Apr 2003 11:53:12 -0400" +Date: Wed, 16 Apr 2003 12:01:56 -0400 +Message-ID: <18664.1050508916@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/144 +X-Sequence-Number: 1650 + +Andrew Sullivan writes: +> But you _could_ write a trigger which inserts into a "staging" table, +> and write a little daemon which only updates the count table with the +> data from the staging table. It's a mighty ugly hack, but it ought +> to work. + +The $64 question with this sort of thing is "how accurate (up-to-date) +does the count have to be?". + +Given that Josh is willing to vacuum every five minutes, he might find +that returning pg_class.reltuples is Close Enough (TM). + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 12:12:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6857F475458 + for ; + Wed, 16 Apr 2003 12:12:24 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 52211475458 + for ; + Wed, 16 Apr 2003 12:11:53 -0400 (EDT) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 195pVu-0002gN-00 + for ; Wed, 16 Apr 2003 12:11:58 -0400 +Received: by dba2 (Postfix, from userid 1019) + id C9F36CF00; Wed, 16 Apr 2003 12:11:58 -0400 (EDT) +Date: Wed, 16 Apr 2003 12:11:58 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: for help! +Message-ID: <20030416161158.GH19999@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: + <200304160848.36431.josh@agliodbs.com> + <20030416155312.GF19999@libertyrms.info> + <18664.1050508916@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <18664.1050508916@sss.pgh.pa.us> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/145 +X-Sequence-Number: 1651 + +On Wed, Apr 16, 2003 at 12:01:56PM -0400, Tom Lane wrote: +> Given that Josh is willing to vacuum every five minutes, he might find +> that returning pg_class.reltuples is Close Enough (TM). + +Certainly, it's not going to be any farther off than the +staging-table+real-table approach, anyway. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 12:26:59 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C976A47636F + for ; + Wed, 16 Apr 2003 12:26:58 -0400 (EDT) +Received: from mail2.mediadesign.nl (md2.mediadesign.nl [212.19.205.67]) + by postgresql.org (Postfix) with SMTP id CC56547633C + for ; + Wed, 16 Apr 2003 12:26:53 -0400 (EDT) +Received: (qmail 5909 invoked by uid 666); 16 Apr 2003 16:26:58 -0000 +Date: Wed, 16 Apr 2003 18:26:58 +0200 +From: Vincent van Leeuwen +To: pgsql-performance@postgresql.org +Subject: the RAID question, again +Message-ID: <20030416162657.GK1836@md2.mediadesign.nl> +Mail-Followup-To: pgsql-performance@postgresql.org +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.3.28i +X-Spam-Status: No, hits=-12.1 required=5.0 tests=BAYES_10,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/146 +X-Sequence-Number: 1652 + +Hi, + +I want to ask the 'which RAID setup is best for PostgreSQL?' question again. +I've read a large portion of the archives of this list, but generally the +answer is 'depends on your needs' with a few different camps. + +My needs are as follows: dedicated PostgreSQL server for a website, which does +much more select queries than insert/updates (although, due to a lot of +caching outside the database, we will be doing more updates than usual for a +website). + +The machine which will be built for this is going to be something like a dual +Xeon 2.4GHz, 4GB RAM, and a SCSI hardware RAID controller with some cache RAM +and 6-7 36GB 15K rpm disks. We have good experiences with ICP Vortex +controllers, so I'll probably end up buying on of those again (the GDT8514RZ +looks nice: http://www.icp-vortex.com/english/product/pci/rzu320/8514rz_e.htm +) + +We normally use Debian linux with a 2.4 kernel, but we're thinking we might +play around with FreeBSD and see how that runs before making the final choice. + +The RAID setup I have in my head is as follows: + +4 disks for a RAID 10 array, for the PG data area +2 disks for a RAID 1 array, for the OS, swap (it won't swap) and, most +importantly, WAL files +1 disk for hot spare + +RAID 1 isn't ideal for a WAL disks because of the (small) write penalty, but +I'm not sure I want to risk losing the WAL files. As far as I know PG doesn't +really like losing them :) This array shouldn't see much I/O outside of the +WAL files, since the OS and PG itself should be completely in RAM when it's +started up. + +RAID 5 is more cost-effective for the data storage, but write-performance is +much lower than RAID 10. + +The hot-spare is non-negotiable, it has saved my life a number of times ;) + +Performance and reliability are the prime concerns for this setup. We normally +run our boxes at extremely high loads because we don't have the budget we +need. Cost is an issue, but since our website is always growing at an insane +pace I'd rather drop some cash on a fast server now and hope to hold out till +the end of this year than having to rush out and buy another mediocre server +in a few months. + +Am I on the right track or does anyone have any tips I could use? + + +On a side note: this box will be bought a few days or weeks from now and +tested during a week or so before we put it in our production environment (if +everything goes well). If anyone is interested in any benchmark results from +it (possibly even FreeBSD vs Linux :)) that can probably be arranged. + + +Vincent van Leeuwen +Media Design - http://www.mediadesign.nl/ + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 11:29:41 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6DE004758F1 + for ; + Thu, 17 Apr 2003 11:29:40 -0400 (EDT) +Received: from spunge-bob.discern.com (dsl092-251-241.sfo2.dsl.speakeasy.net + [66.92.251.241]) + by postgresql.org (Postfix) with ESMTP id B6545475458 + for ; + Thu, 17 Apr 2003 11:29:39 -0400 (EDT) +Received: by spunge-bob.discern.com (Postfix, from userid 1000) + id E89FD27C88; Wed, 16 Apr 2003 15:02:49 -0700 (PDT) +Subject: dum query plan: more info. +From: Jonathan Moore +To: pgsql-performance@postgresql.org +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.5 +Date: 16 Apr 2003 15:02:49 -0700 +Message-Id: <1050530569.20873.120.camel@spunge-bob> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-12.0 required=5.0 + tests=BAYES_10,DATE_IN_PAST_12_24,USER_AGENT_XIMIAN + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/153 +X-Sequence-Number: 1659 + +I now under stand that my join was rong but none of the seguestions are +the optimal solution to the problime. You can make this order n if you +try. The trick is to use a mearg join using sorted list of the unique +keys in each colum join. The question you are asking is what left hand +entrys do not exist on the right. + +select A.left form pairs A, pairs B where A.left != B.right; + +(note: my code in the first example select left form the rong table but +it dosn't change the search.) + +take the DB: + +(1,2) +(2,1) +(1,5) +(4,5) +(5,2) + +Sort the colums: +left right +==== ===== + 1 1 + 2 2 + 4 5 + 5 + +Start at the top you see that you have 1 in both columes there for you +know that 1 is not a answer. pop both colums. same for 2. Whe you get to +the top of the lists as 4, 5; you know that 4 apperas on the only in the +left colum as you don't see it on the right. pop the left colum. now you +see that 5 is on both sides so 5 is not a canadate. You are out of +options so you are done 4 is the only value that is on the left and only +on the left. + +This methoud is order O(n) if both colums have b-tree indexes so you +don't have to pre sort them othere wise it is O(n*log(n)) as the sort is +the greatest complexity. In eathere case it is way better then O(n^2) +for almost any n. + +I have this implmented in my code by selecting each colum and then doing +the mearg my self more expensive then a in db join as there is pointless +data copys. + +sudo perl for the hole thing is: + +#!/usr/bin/not-realy-perl + +my @left = select distinct left_entry from entry_pairs order by +left_entry; + +my @right = select distinct right_entry from entry_pairs order by +right_entry; + +my @only_left; + +while (1) { + if (not @left) { + last; #done + } + + elsif (not @right) { + push @only_left, $left[0]; + pop @left; + } + + elsif ($left[0] == $right[0]) { + pop @left; + pop @right; + } + + elsif ($left[0] < $right[0]) { + push @only_left, $left[0]; + pop @left; + } + + elsif ($left[0] > $right[0]) { + pop @right; + } +} + + + +-Jonathan + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 21:21:29 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E1FFE47610C + for ; + Wed, 16 Apr 2003 21:21:28 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 225A0475FC8 + for ; + Wed, 16 Apr 2003 21:21:28 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id DDA3CD616; Wed, 16 Apr 2003 18:21:31 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id D35045C04; Wed, 16 Apr 2003 18:21:31 -0700 (PDT) +Date: Wed, 16 Apr 2003 18:21:31 -0700 (PDT) +From: Stephan Szabo +To: Jonathan Moore +Cc: +Subject: Re: dum query plan +In-Reply-To: <1050476308.20872.19.camel@spunge-bob> +Message-ID: <20030416175935.T79767-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/148 +X-Sequence-Number: 1654 + + +On 15 Apr 2003, Jonathan Moore wrote: + +> I am wondering why it uses the O(n^2) nested loop when there is a O(N) +> methoud using btree indexes for a merg join. I am using 7.2.1 would +> upgrading fix my problime or is it somthing else? +> +> Given the schema: +> +> drop table Entry_Pairs; +> create table Entry_Pairs ( +> left_entry int REFERENCES Entry ON DELETE RESTRICT, +> right_entry int REFERENCES Entry ON DELETE RESTRICT, +> relation int NOT NULL , +> subtract bool NOT NULL , +> comment int NULL REFERENCES Comment ON DELETE SET NULL, +> UNIQUE (left_entry, right_entry, relation) +> ); +> CREATE INDEX entry_pairs_left_index ON entry_pairs (left_entry); +> CREATE INDEX entry_pairs_right_index ON entry_pairs (right_entry); +> -- +> +> You get this" +> +> dblex=> explain select A.left_entry from entry_pairs A, entry_pairs B +> where A.right_entry != B.left_entry; +> NOTICE: QUERY PLAN: +> +> Nested Loop (cost=100000000.00..102876671.17 rows=97545252 width=12) +> -> Seq Scan on entry_pairs a (cost=0.00..167.77 rows=9877 width=8) +> -> Seq Scan on entry_pairs b (cost=0.00..167.77 rows=9877 width=4) +> +> EXPLAIN +> +> That is dum. If you just walk both B-Tree indexes there is a O(n) +> search. I tryed to turn off netsed loops but it still did it. (the +> reason the cost is 100000000.00 is a artifact from turing off loops) + +Can you describe the algorithm you think it should be taking with perhaps +a small set of data like say (given only left and right): + +(1,2) +(3,4) +(5,6) + +(I think the query should return 1,1,1,3,3,3,5,5,5 for this case) + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 22:32:55 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DA574475A45 + for ; + Wed, 16 Apr 2003 22:32:53 -0400 (EDT) +Received: from c001.snv.cp.net (h013.c001.snv.cp.net [209.228.32.127]) + by postgresql.org (Postfix) with SMTP id A9ECE475458 + for ; + Wed, 16 Apr 2003 22:32:52 -0400 (EDT) +Received: (cpmta 1682 invoked from network); 16 Apr 2003 19:32:56 -0700 +Received: from 209.228.32.120 (HELO mail.dilger.cc.criticalpath.net) + by smtp.register-admin.com (209.228.32.127) with SMTP; + 16 Apr 2003 19:32:56 -0700 +X-Sent: 17 Apr 2003 02:32:56 GMT +Received: from [216.68.146.219] by mail.dilger.cc with HTTP; + Wed, 16 Apr 2003 19:32:54 -0700 (PDT) +Content-Type: text/plain; charset=iso-8859-1 +Content-Disposition: inline +Content-Transfer-Encoding: 7bit +MIME-Version: 1.0 +To: pgsql.spam@vinz.nl +Cc: pgsql-performance@postgresql.org +From: "Nikolaus Dilger" +Subject: Re: the RAID question, again +X-Sent-From: nikolaus@dilger.cc +Date: Wed, 16 Apr 2003 19:32:54 -0700 (PDT) +X-Mailer: Web Mail 5.3.0-6_sol28 +Message-Id: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> +X-Spam-Status: No, hits=-12.9 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,QUOTE_TWICE_1 + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/149 +X-Sequence-Number: 1655 + +Vincent, + +In my eyes the best disk I/O configuration is a balance +of performance, price and administrative effort. + +Your set-up looks relatively good. Howver, price seems +not to be your greatest concern. Otherwise you would +favor RAID 5 and/or leave out the spare disk. + +One improvement area may be to put all 6 disks into a +RAID 10 group. That way you have more I/O bandwith. + +One watchout is that the main memory of your machine +may be better than the one of your RAID controller. +The RAID controller has Integrated 128MB PC133 ECC +SDRAM. You did not state what kind of memory your +server has. + +Regards, +Nikolaus + +On Wed, 16 Apr 2003 18:26:58 +0200, Vincent van Leeuwen +wrote: + +> +> Hi, +> +> I want to ask the 'which RAID setup is best for +> PostgreSQL?' question again. +> I've read a large portion of the archives of this +list, +> but generally the +> answer is 'depends on your needs' with a few different +> camps. +> +> My needs are as follows: dedicated PostgreSQL server +> for a website, which does +> much more select queries than insert/updates +(although, +> due to a lot of +> caching outside the database, we will be doing more +> updates than usual for a +> website). +> +> The machine which will be built for this is going to +be +> something like a dual +> Xeon 2.4GHz, 4GB RAM, and a SCSI hardware RAID +> controller with some cache RAM +> and 6-7 36GB 15K rpm disks. We have good experiences +> with ICP Vortex +> controllers, so I'll probably end up buying on of +those +> again (the GDT8514RZ +> looks nice: +> +http://www.icp-vortex.com/english/product/pci/rzu320/8514rz_e.htm +> ) +> +> We normally use Debian linux with a 2.4 kernel, but +> we're thinking we might +> play around with FreeBSD and see how that runs before +> making the final choice. +> +> The RAID setup I have in my head is as follows: +> +> 4 disks for a RAID 10 array, for the PG data area +> 2 disks for a RAID 1 array, for the OS, swap (it won't +> swap) and, most +> importantly, WAL files +> 1 disk for hot spare +> +> RAID 1 isn't ideal for a WAL disks because of the +> (small) write penalty, but +> I'm not sure I want to risk losing the WAL files. As +> far as I know PG doesn't +> really like losing them :) This array shouldn't see +> much I/O outside of the +> WAL files, since the OS and PG itself should be +> completely in RAM when it's +> started up. +> +> RAID 5 is more cost-effective for the data storage, +but +> write-performance is +> much lower than RAID 10. +> +> The hot-spare is non-negotiable, it has saved my life +a +> number of times ;) +> +> Performance and reliability are the prime concerns for +> this setup. We normally +> run our boxes at extremely high loads because we don't +> have the budget we +> need. Cost is an issue, but since our website is +always +> growing at an insane +> pace I'd rather drop some cash on a fast server now +and +> hope to hold out till +> the end of this year than having to rush out and buy +> another mediocre server +> in a few months. +> +> Am I on the right track or does anyone have any tips I +> could use? +> +> +> On a side note: this box will be bought a few days or +> weeks from now and +> tested during a week or so before we put it in our +> production environment (if +> everything goes well). If anyone is interested in any +> benchmark results from +> it (possibly even FreeBSD vs Linux :)) that can +> probably be arranged. +> +> +> Vincent van Leeuwen +> Media Design - http://www.mediadesign.nl/ +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the +> unregister command +> (send "unregister YourEmailAddressHere" to +> majordomo@postgresql.org) + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 23:15:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BCB06475956 + for ; + Wed, 16 Apr 2003 23:15:42 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id BAAAA475458 + for ; + Wed, 16 Apr 2003 23:15:38 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3H3FVU6002844; + Wed, 16 Apr 2003 23:15:31 -0400 (EDT) +To: Jonathan Moore +Cc: pgsql-performance@postgresql.org +Subject: Re: dum query plan +In-reply-to: <1050476308.20872.19.camel@spunge-bob> +References: <1050476308.20872.19.camel@spunge-bob> +Comments: In-reply-to Jonathan Moore + message dated "15 Apr 2003 23:58:28 -0700" +Date: Wed, 16 Apr 2003 23:15:31 -0400 +Message-ID: <2843.1050549331@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/150 +X-Sequence-Number: 1656 + +Jonathan Moore writes: +> I am wondering why it uses the O(n^2) nested loop when there is a O(N) +> methoud using btree indexes for a merg join. + +With an inequality for the WHERE condition? I don't think so. The +expected output is of size O(N^2), so how could the algorithm take +less than O(N^2) steps? + +> dblex=> explain select A.left_entry from entry_pairs A, entry_pairs B +> where A.right_entry != B.left_entry; + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 16 23:21:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6E025475ECE + for ; + Wed, 16 Apr 2003 23:21:06 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id B6251475A45 + for ; + Wed, 16 Apr 2003 23:21:05 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2968753; Wed, 16 Apr 2003 20:21:05 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Nikolaus Dilger" , pgsql.spam@vinz.nl +Subject: Re: the RAID question, again +Date: Wed, 16 Apr 2003 20:20:50 -0700 +User-Agent: KMail/1.4.3 +Cc: pgsql-performance@postgresql.org +References: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> +In-Reply-To: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> +MIME-Version: 1.0 +Message-Id: <200304162020.50103.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-21.9 required=5.0 + tests=BAYES_10,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/151 +X-Sequence-Number: 1657 + +Vincent, + +> One watchout is that the main memory of your machine +> may be better than the one of your RAID controller. +> The RAID controller has Integrated 128MB PC133 ECC +> SDRAM. You did not state what kind of memory your +> server has. + +Nickolaus has a good point. With a high-end Linux server, and a medium-en= +d=20 +RAID card, it's sometimes faster to use Linux software RAID than harware=20 +raid. Not all the time, though. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 10:11:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id ECAF7475D91 + for ; + Thu, 17 Apr 2003 10:11:19 -0400 (EDT) +Received: from beamish.nsd.ca (beamish.nsd.ca [205.150.156.194]) + by postgresql.org (Postfix) with ESMTP id DF6D3475F1B + for ; + Thu, 17 Apr 2003 10:11:15 -0400 (EDT) +Received: (from smap@localhost) by beamish.nsd.ca (8.9.3/8.9.3) id KAA30572; + Thu, 17 Apr 2003 10:11:07 -0400 +X-Authentication-Warning: beamish.nsd.ca: smap set sender to + using -f +Received: from reddog.nsd.ca(192.168.101.30) by beamish.nsd.ca via smap + (V2.1/2.1+anti-relay+anti-spam) + id xma030568; Thu, 17 Apr 03 10:11:02 -0400 +Received: from nsd.ca (jllachan-linux.nsd.ca [192.168.101.148]) + by reddog.nsd.ca (8.8.7/8.8.7) with ESMTP id KAA27904; + Thu, 17 Apr 2003 10:05:29 -0400 +Message-ID: <3E9EB653.B6E200B4@nsd.ca> +Date: Thu, 17 Apr 2003 10:12:35 -0400 +From: Jean-Luc Lachance +X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.18-24.7.x i686) +X-Accept-Language: en +MIME-Version: 1.0 +To: Jonathan Moore +Cc: pgsql-performance@postgresql.org +Subject: Re: dum query plan +References: <1050476308.20872.19.camel@spunge-bob> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-30.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,X_AUTH_WARNING autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/152 +X-Sequence-Number: 1658 + +Your WHERE clause is the reason you get O(N^2). + +How about describing in words what you want. + +maybe what you really want is: + +select left_entry from entry_pairs A where not exists ( + select 1 from entry_pairs B where A.right_entry = B.left_entry) + +JLL + +Jonathan Moore wrote: +> +> I am wondering why it uses the O(n^2) nested loop when there is a O(N) +> methoud using btree indexes for a merg join. I am using 7.2.1 would +> upgrading fix my problime or is it somthing else? +> +> Given the schema: +> +> drop table Entry_Pairs; +> create table Entry_Pairs ( +> left_entry int REFERENCES Entry ON DELETE RESTRICT, +> right_entry int REFERENCES Entry ON DELETE RESTRICT, +> relation int NOT NULL , +> subtract bool NOT NULL , +> comment int NULL REFERENCES Comment ON DELETE SET NULL, +> UNIQUE (left_entry, right_entry, relation) +> ); +> CREATE INDEX entry_pairs_left_index ON entry_pairs (left_entry); +> CREATE INDEX entry_pairs_right_index ON entry_pairs (right_entry); +> -- +> +> You get this" +> +> dblex=> explain select A.left_entry from entry_pairs A, entry_pairs B +> where A.right_entry != B.left_entry; +> NOTICE: QUERY PLAN: +> +> Nested Loop (cost=100000000.00..102876671.17 rows=97545252 width=12) +> -> Seq Scan on entry_pairs a (cost=0.00..167.77 rows=9877 width=8) +> -> Seq Scan on entry_pairs b (cost=0.00..167.77 rows=9877 width=4) +> +> EXPLAIN +> +> That is dum. If you just walk both B-Tree indexes there is a O(n) +> search. I tryed to turn off netsed loops but it still did it. (the +> reason the cost is 100000000.00 is a artifact from turing off loops) +> +> -Jonathan +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: Have you searched our list archives? +> +> http://archives.postgresql.org + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 12:28:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A0CAD475C15 + for ; + Thu, 17 Apr 2003 12:28:31 -0400 (EDT) +Received: from email02.aon.at (WARSL401PIP7.highway.telekom.at [195.3.96.94]) + by postgresql.org (Postfix) with SMTP id 3034C475C3D + for ; + Thu, 17 Apr 2003 12:28:22 -0400 (EDT) +Received: (qmail 401110 invoked from network); 17 Apr 2003 16:24:24 -0000 +Received: from m160p004.dipool.highway.telekom.at (HELO cantor) + ([62.46.9.228]) (envelope-sender ) + by qmail2rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 17 Apr 2003 16:24:24 -0000 +From: Manfred Koizar +To: Jonathan Moore +Cc: pgsql-performance@postgresql.org +Subject: Re: dum query plan: more info. +Date: Thu, 17 Apr 2003 18:24:24 +0200 +Message-ID: +References: <1050530569.20873.120.camel@spunge-bob> +In-Reply-To: <1050530569.20873.120.camel@spunge-bob> +X-Mailer: Forte Agent 1.8/32.548 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-32.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_FORTE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/154 +X-Sequence-Number: 1660 + +On 16 Apr 2003 15:02:49 -0700, Jonathan Moore +wrote: +>select A.left form pairs A, pairs B where A.left != B.right; +> +>take the DB: +> +>(1,2) +>(2,1) +>(1,5) +>(4,5) +>(5,2) +> +>[...] 4 is the only value that is on the left and only +>on the left. + +But this is not the answer to your SQL statement. The correct answer +is: + left +------ + 1 + 1 + 1 + 1 + 2 + 2 + 2 + 1 + 1 + 1 + 1 + 4 + 4 + 4 + 4 + 4 + 5 + 5 + 5 +(19 rows) + +What you are looking for is more like + + SELECT left FROM pairs + EXCEPT + SELECT right FROM pairs; + +>This methoud is order O(n) if both colums have b-tree indexes so you +>don't have to pre sort them othere wise it is O(n*log(n)) as the sort is +>the greatest complexity. In eathere case it is way better then O(n^2) +>for almost any n. + +And I'm sure it will not take O(n^2) time in Postgres. + +Servus + Manfred + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 12:31:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 1762A4762A2 + for ; + Thu, 17 Apr 2003 12:31:47 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id A27A3476141 + for ; + Thu, 17 Apr 2003 12:31:45 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3HGVnU6011333; + Thu, 17 Apr 2003 12:31:49 -0400 (EDT) +To: Jonathan Moore +Cc: pgsql-performance@postgresql.org +Subject: Re: dum query plan: more info. +In-reply-to: <1050530569.20873.120.camel@spunge-bob> +References: <1050530569.20873.120.camel@spunge-bob> +Comments: In-reply-to Jonathan Moore + message dated "16 Apr 2003 15:02:49 -0700" +Date: Thu, 17 Apr 2003 12:31:49 -0400 +Message-ID: <11332.1050597109@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/155 +X-Sequence-Number: 1661 + +Jonathan Moore writes: +> I now under stand that my join was rong but none of the seguestions are +> the optimal solution to the problime. You can make this order n if you +> try. The trick is to use a mearg join using sorted list of the unique +> keys in each colum join. The question you are asking is what left hand +> entrys do not exist on the right. + +In that case maybe what you are after is + +select a.* from a left join b on (a.left = b.right) where b.right is null; + +which is a pretty grotty hack using the outer-join rules, but should +work efficiently. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 13:48:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 95FAC475458 + for ; + Thu, 17 Apr 2003 13:48:17 -0400 (EDT) +Received: from smtp.kocks.com (adsl-66-124-90-234.dsl.snfc21.pacbell.net + [66.124.90.234]) + by postgresql.org (Postfix) with ESMTP id 4205A4758F1 + for ; + Thu, 17 Apr 2003 13:48:16 -0400 (EDT) +Received: from GARP (fwinside.kocks.com [10.10.10.1]) + by smtp.kocks.com (mail) with SMTP id 2208128BDA + for ; + Thu, 17 Apr 2003 10:48:16 -0700 (PDT) +Reply-To: +From: "dex" +To: +Subject: Performance of Inherits versus Views +Date: Thu, 17 Apr 2003 10:48:16 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-8.8 required=5.0 tests=BAYES_20,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/156 +X-Sequence-Number: 1662 + +Hello, + +Is it more efficient to use a schema with Inherits or +schema with Views. I can see logically how to use both +for my case and I'm trying to make a decision. I would +guess that the overhead of the queries against +inherited tables is higher than queries against views, +but I don't know. + +At the bottom of this message, I've included the cities / +capitals examples implemented both as schema using +inheritance and as schema using views. + +Using the example, I could make queries such as: + +SELECT name FROM capitals; -- capitals in inherited + +or + +SELECT name FROM capital_cities; -- capital cities is a view + +But which one would be faster? In my real world example, +I will either have one small base class table (i.e. cities in +the example) and many direct descendents of that base +table (e.g. capitals, beaches, national parks, suburbs +in the example). Or, it could be implemented as one larger +(but not huge) lookup table with many views against +that lookup table. + +What would you do? + +Thanks! + +--dex + + +-- +-- Schema with Inherits +-- +CREATE TABLE cities ( + name text, + population float, + altitude int -- (in ft) + ); + + CREATE TABLE capitals ( + state char(2) + ) INHERITS (cities); + + +-- +-- Schema with View +-- +CREATE TABLE all_cities ( + name text, + population float, + altitude int, + state char(2) +); + +CREATE VIEW just_cities AS SELECT + all_cities.name, + all_cities.population, + all_cities.altitude +FROM all_cities; + +-- or perhaps with a where clause, as in +CREATE VIEW capital_cities AS SELECT + all_cities.name, + all_cities.population, + all_cities.altitude +FROM all_cities WHERE (all_cities.state IS NOT NULL); + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 15:17:11 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6BE434758F1 + for ; + Thu, 17 Apr 2003 15:17:09 -0400 (EDT) +Received: from mail.cs.umass.edu (loki.cs.umass.edu [128.119.243.168]) + by postgresql.org (Postfix) with ESMTP id 7F982475458 + for ; + Thu, 17 Apr 2003 15:17:08 -0400 (EDT) +Received: from phobos.cs.umass.edu (phobos.cs.umass.edu [128.119.243.161]) + by mail.cs.umass.edu (8.12.6/8.12.5) with ESMTP id h3HJH8jh012376 + (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT) + for ; Thu, 17 Apr 2003 15:17:08 -0400 +Date: Thu, 17 Apr 2003 15:17:01 -0400 (EDT) +From: Victor Danilchenko +To: pgsql-performance@postgresql.org +Subject: Query speed problems +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Checked: This message probably not SPAM +X-Spam-Score: -5.8, Required: 5 +X-Spam-Tests: USER_AGENT_PINE +X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com / mimedefang) +X-Spam-Status: No, hits=-12.3 required=5.0 tests=BAYES_01,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/157 +X-Sequence-Number: 1663 + + Hi, + + In the process of developing an API for web/perl/postrgres +interactions, I have come up against a peculiar problem; a rather simple +query, run on two relatively small tables, takes as much as 0.4 seconds +on my development system (it's a P2 266, which in this case is a good +thing, as it exposes speed issues). I tried accomplishging the same +thing via subqueries and joins, and both methods give me similarly bad +result (join query is a little slower, but only a little). + + The queries I have tested are as follows: + +SELECT DISTINCT maker.* FROM maker,model WHERE maker.id=model.maker +SELECT DISTINCT maker.* FROM maker join model ON maker.id=model.maker + + The point of the queries is to extract only the maker rows which +are referenced from the model table. I would happily use another way to +achieve the same end, should anyone suggest it. + + "maker" has only 137 rows, "model" only 1233 rows. I test the +performance in perl, by taking time right before and after query +execution. Executing the queries takes anywhere between .3 and .5 +seconds, depending on some other factors (removing the 'distinct' +keyword from the 1st query shaves about .1 second off of the execution +time for example). + + These execution times seem ridiculous. Any idea what the culprit +may be? I hope it's not the text fields, 'cuz those fields are +important. + + Both tables are quite simple: + +# \d maker + Table "public.maker" + Column | Type | Modifiers +------------+-----------------------+----------- + id | character varying(4) | not null + fullname | character varying(20) | + contact | character varying(20) | + phone | character varying(15) | + service_no | character varying(20) | + lastuser | character varying(30) | + comments | text | +Indexes: maker_pkey primary key btree (id) +Triggers: RI_ConstraintTrigger_18881, + RI_ConstraintTrigger_18882 + +# \d model + Table "public.model" + Column | Type | Modifiers +---------------+-----------------------+--------------------------------------------- + id | integer | not null default nextval('model_ids'::text) + name | character varying(20) | not null + maker | character varying(4) | + type_hardware | character varying(4) | + fullname | character varying(40) | + spec | character varying(50) | + lastuser | character varying(30) | + comments | text | + size_cap | character varying(10) | +Indexes: model_pkey primary key btree (id), + unique_model unique btree (name, maker, type_hardware) +Check constraints: "nonempty_fullname" (fullname > ''::character varying) +Foreign Key constraints: valid_maker FOREIGN KEY (maker) REFERENCES \ + maker(id) ON UPDATE NO ACTION ON DELETE NO ACTION, + valid_type FOREIGN KEY (type_hardware) +REFERENCES type_hardware(id) ON UPDATE NO ACTION ON DELETE NO ACTION + +-- +| Victor Danilchenko | Any sufficiently advanced | +| danilche@cs.umass.edu | technology is indistinguishable | +| CSCF | 5-4231 | from a Perl script. | + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 15:38:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C1F674758F1 + for ; + Thu, 17 Apr 2003 15:38:42 -0400 (EDT) +Received: from mail.cs.umass.edu (loki.cs.umass.edu [128.119.243.168]) + by postgresql.org (Postfix) with ESMTP id 12547475458 + for ; + Thu, 17 Apr 2003 15:38:42 -0400 (EDT) +Received: from phobos.cs.umass.edu (phobos.cs.umass.edu [128.119.243.161]) + by mail.cs.umass.edu (8.12.6/8.12.5) with ESMTP id h3HJcgjh016856 + (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT) + for ; Thu, 17 Apr 2003 15:38:42 -0400 +Date: Thu, 17 Apr 2003 15:38:37 -0400 (EDT) +From: Victor Danilchenko +To: pgsql-performance@postgresql.org +Subject: Re: Query speed problems +In-Reply-To: +Message-ID: +References: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Checked: This message probably not SPAM +X-Spam-Score: -15.7, Required: 5 +X-Spam-Tests: IN_REP_TO,REFERENCES,USER_AGENT_PINE +X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com / mimedefang) +X-Spam-Status: No, hits=-22.0 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/158 +X-Sequence-Number: 1664 + + Sorry, I forgot to specify software versions. + + I am running RHL 8.0 (Linux kernel 2.4.18), and postgres 7.3. + +-- +| Victor Danilchenko +------------------------------------+ +| danilche@cs.umass.edu | I don't have to outrun the bear -- | +| CSCF | 5-4231 | I just have to outrun YOU! | + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 15:55:15 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A79084758F1 + for ; + Thu, 17 Apr 2003 15:55:13 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id E4C1D475458 + for ; + Thu, 17 Apr 2003 15:55:09 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id E1FDAD612; Thu, 17 Apr 2003 12:55:10 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id D7AAB5C03; Thu, 17 Apr 2003 12:55:10 -0700 (PDT) +Date: Thu, 17 Apr 2003 12:55:10 -0700 (PDT) +From: Stephan Szabo +To: Victor Danilchenko +Cc: +Subject: Re: Query speed problems +In-Reply-To: +Message-ID: <20030417125211.J91312-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/159 +X-Sequence-Number: 1665 + + +On Thu, 17 Apr 2003, Victor Danilchenko wrote: + +> The queries I have tested are as follows: +> +> SELECT DISTINCT maker.* FROM maker,model WHERE maker.id=model.maker +> SELECT DISTINCT maker.* FROM maker join model ON maker.id=model.maker +> +> The point of the queries is to extract only the maker rows which +> are referenced from the model table. I would happily use another way to +> achieve the same end, should anyone suggest it. + +What does explain analyze show for the query? + +> "maker" has only 137 rows, "model" only 1233 rows. I test the +> performance in perl, by taking time right before and after query +> execution. Executing the queries takes anywhere between .3 and .5 +> seconds, depending on some other factors (removing the 'distinct' +> keyword from the 1st query shaves about .1 second off of the execution +> time for example). + +> Column | Type | Modifiers +> ---------------+-----------------------+--------------------------------------------- +> id | integer | not null default nextval('model_ids'::text) +> name | character varying(20) | not null +> maker | character varying(4) | +> type_hardware | character varying(4) | +> fullname | character varying(40) | +> spec | character varying(50) | +> lastuser | character varying(30) | +> comments | text | +> size_cap | character varying(10) | +> Indexes: model_pkey primary key btree (id), +> unique_model unique btree (name, maker, type_hardware) +> Check constraints: "nonempty_fullname" (fullname > ''::character varying) +> Foreign Key constraints: valid_maker FOREIGN KEY (maker) REFERENCES \ +> maker(id) ON UPDATE NO ACTION ON DELETE NO ACTION, +> valid_type FOREIGN KEY (type_hardware) +> REFERENCES type_hardware(id) ON UPDATE NO ACTION ON DELETE NO ACTION + +Hmm, it doesn't look to me like model.maker= type queries are +indexable with this set of things. An index on model(maker) might help. + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 15:59:07 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A9FCD475956 + for ; + Thu, 17 Apr 2003 15:59:05 -0400 (EDT) +Received: from mail.speakeasy.net (mail14.speakeasy.net [216.254.0.214]) + by postgresql.org (Postfix) with ESMTP id 7E0B547592C + for ; + Thu, 17 Apr 2003 15:59:04 -0400 (EDT) +Received: (qmail 20098 invoked from network); 17 Apr 2003 19:59:12 -0000 +Received: from unknown (HELO pdarley) (kinesis@[64.81.9.230]) + (envelope-sender ) + by mail14.speakeasy.net (qmail-ldap-1.03) with SMTP + for ; 17 Apr 2003 19:59:12 -0000 +From: "Peter Darley" +To: "Victor Danilchenko" , + +Subject: Re: Query speed problems +Date: Thu, 17 Apr 2003 12:59:07 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) +In-Reply-To: +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-21.0 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE,ORIGINAL_MESSAGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/160 +X-Sequence-Number: 1666 + +Victor, + I'm not sure, but I think an exists might be faster for you. It wouldn't +have to deal with the Cartesian product of the tables. + +SELECT DISTINCT maker.* FROM maker WHERE exists (SELECT 1 FROM model WHERE +model.maker=maker.id); + +Thanks, +Peter Darley + +-----Original Message----- +From: pgsql-performance-owner@postgresql.org +[mailto:pgsql-performance-owner@postgresql.org]On Behalf Of Victor +Danilchenko +Sent: Thursday, April 17, 2003 12:17 PM +To: pgsql-performance@postgresql.org +Subject: [PERFORM] Query speed problems + + + Hi, + + In the process of developing an API for web/perl/postrgres +interactions, I have come up against a peculiar problem; a rather simple +query, run on two relatively small tables, takes as much as 0.4 seconds +on my development system (it's a P2 266, which in this case is a good +thing, as it exposes speed issues). I tried accomplishging the same +thing via subqueries and joins, and both methods give me similarly bad +result (join query is a little slower, but only a little). + + The queries I have tested are as follows: + +SELECT DISTINCT maker.* FROM maker,model WHERE maker.id=model.maker +SELECT DISTINCT maker.* FROM maker join model ON maker.id=model.maker + + The point of the queries is to extract only the maker rows which +are referenced from the model table. I would happily use another way to +achieve the same end, should anyone suggest it. + + "maker" has only 137 rows, "model" only 1233 rows. I test the +performance in perl, by taking time right before and after query +execution. Executing the queries takes anywhere between .3 and .5 +seconds, depending on some other factors (removing the 'distinct' +keyword from the 1st query shaves about .1 second off of the execution +time for example). + + These execution times seem ridiculous. Any idea what the culprit +may be? I hope it's not the text fields, 'cuz those fields are +important. + + Both tables are quite simple: + +# \d maker + Table "public.maker" + Column | Type | Modifiers +------------+-----------------------+----------- + id | character varying(4) | not null + fullname | character varying(20) | + contact | character varying(20) | + phone | character varying(15) | + service_no | character varying(20) | + lastuser | character varying(30) | + comments | text | +Indexes: maker_pkey primary key btree (id) +Triggers: RI_ConstraintTrigger_18881, + RI_ConstraintTrigger_18882 + +# \d model + Table "public.model" + Column | Type | Modifiers +---------------+-----------------------+------------------------------------ +--------- + id | integer | not null default +nextval('model_ids'::text) + name | character varying(20) | not null + maker | character varying(4) | + type_hardware | character varying(4) | + fullname | character varying(40) | + spec | character varying(50) | + lastuser | character varying(30) | + comments | text | + size_cap | character varying(10) | +Indexes: model_pkey primary key btree (id), + unique_model unique btree (name, maker, type_hardware) +Check constraints: "nonempty_fullname" (fullname > ''::character varying) +Foreign Key constraints: valid_maker FOREIGN KEY (maker) REFERENCES \ + maker(id) ON UPDATE NO ACTION ON DELETE NO +ACTION, + valid_type FOREIGN KEY (type_hardware) +REFERENCES type_hardware(id) ON UPDATE NO ACTION ON DELETE NO ACTION + +-- +| Victor Danilchenko | Any sufficiently advanced | +| danilche@cs.umass.edu | technology is indistinguishable | +| CSCF | 5-4231 | from a Perl script. | + + +---------------------------(end of broadcast)--------------------------- +TIP 2: you can get off all lists at once with the unregister command + (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 16:24:26 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DD62F4758F1 + for ; + Thu, 17 Apr 2003 16:24:24 -0400 (EDT) +Received: from mail.cs.umass.edu (loki.cs.umass.edu [128.119.243.168]) + by postgresql.org (Postfix) with ESMTP id E3BA8475458 + for ; + Thu, 17 Apr 2003 16:24:23 -0400 (EDT) +Received: from phobos.cs.umass.edu (phobos.cs.umass.edu [128.119.243.161]) + by mail.cs.umass.edu (8.12.6/8.12.5) with ESMTP id h3HKOMjh029751 + (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT); + Thu, 17 Apr 2003 16:24:22 -0400 +Date: Thu, 17 Apr 2003 16:24:17 -0400 (EDT) +From: Victor Danilchenko +To: Peter Darley +Cc: pgsql-performance@postgresql.org +Subject: Re: Query speed problems +In-Reply-To: +Message-ID: +References: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Checked: This message probably not SPAM +X-Spam-Score: -32.2, Required: 5 +X-Spam-Tests: EMAIL_ATTRIBUTION, IN_REP_TO, QUOTED_EMAIL_TEXT, REFERENCES, + REPLY_WITH_QUOTES, USER_AGENT_PINE +X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com / mimedefang) +X-Spam-Status: No, hits=-38.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/161 +X-Sequence-Number: 1667 + +On Thu, 17 Apr 2003, Peter Darley wrote: + +>Victor, +> I'm not sure, but I think an exists might be faster for you. It wouldn't +>have to deal with the Cartesian product of the tables. +> +>SELECT DISTINCT maker.* FROM maker WHERE exists (SELECT 1 FROM model WHERE +>model.maker=maker.id); + + That was indeed significantly faster. *very* significantly +faster. + + As you may guess, I am an SQL newbie, and working my way through +the language. I figured there would be a faster way to do what I was +doing, but sunqueries or joins was the only way I could figure out. + + Again, thanks for the helpful reply, and for your promptness. I +still want to figure out why the subquery version was taking so damned +long, but it's nice to have a working fast solution. + +>-----Original Message----- +>From: pgsql-performance-owner@postgresql.org +>[mailto:pgsql-performance-owner@postgresql.org]On Behalf Of Victor +>Danilchenko +>Sent: Thursday, April 17, 2003 12:17 PM +>To: pgsql-performance@postgresql.org +>Subject: [PERFORM] Query speed problems +> +> +> Hi, +> +> In the process of developing an API for web/perl/postrgres +>interactions, I have come up against a peculiar problem; a rather simple +>query, run on two relatively small tables, takes as much as 0.4 seconds +>on my development system (it's a P2 266, which in this case is a good +>thing, as it exposes speed issues). I tried accomplishging the same +>thing via subqueries and joins, and both methods give me similarly bad +>result (join query is a little slower, but only a little). +> +> The queries I have tested are as follows: +> +>SELECT DISTINCT maker.* FROM maker,model WHERE maker.id=model.maker +>SELECT DISTINCT maker.* FROM maker join model ON maker.id=model.maker +> +> The point of the queries is to extract only the maker rows which +>are referenced from the model table. I would happily use another way to +>achieve the same end, should anyone suggest it. +> +> "maker" has only 137 rows, "model" only 1233 rows. I test the +>performance in perl, by taking time right before and after query +>execution. Executing the queries takes anywhere between .3 and .5 +>seconds, depending on some other factors (removing the 'distinct' +>keyword from the 1st query shaves about .1 second off of the execution +>time for example). +> +> These execution times seem ridiculous. Any idea what the culprit +>may be? I hope it's not the text fields, 'cuz those fields are +>important. +> +> Both tables are quite simple: +> +># \d maker +> Table "public.maker" +> Column | Type | Modifiers +>------------+-----------------------+----------- +> id | character varying(4) | not null +> fullname | character varying(20) | +> contact | character varying(20) | +> phone | character varying(15) | +> service_no | character varying(20) | +> lastuser | character varying(30) | +> comments | text | +>Indexes: maker_pkey primary key btree (id) +>Triggers: RI_ConstraintTrigger_18881, +> RI_ConstraintTrigger_18882 +> +># \d model +> Table "public.model" +> Column | Type | Modifiers +>---------------+-----------------------+------------------------------------ +>--------- +> id | integer | not null default +>nextval('model_ids'::text) +> name | character varying(20) | not null +> maker | character varying(4) | +> type_hardware | character varying(4) | +> fullname | character varying(40) | +> spec | character varying(50) | +> lastuser | character varying(30) | +> comments | text | +> size_cap | character varying(10) | +>Indexes: model_pkey primary key btree (id), +> unique_model unique btree (name, maker, type_hardware) +>Check constraints: "nonempty_fullname" (fullname > ''::character varying) +>Foreign Key constraints: valid_maker FOREIGN KEY (maker) REFERENCES \ +> maker(id) ON UPDATE NO ACTION ON DELETE NO +>ACTION, +> valid_type FOREIGN KEY (type_hardware) +>REFERENCES type_hardware(id) ON UPDATE NO ACTION ON DELETE NO ACTION +> +>-- +>| Victor Danilchenko | Any sufficiently advanced | +>| danilche@cs.umass.edu | technology is indistinguishable | +>| CSCF | 5-4231 | from a Perl script. | +> +> +>---------------------------(end of broadcast)--------------------------- +>TIP 2: you can get off all lists at once with the unregister command +> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) +> +> +>---------------------------(end of broadcast)--------------------------- +>TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org +> + +-- +| Victor Danilchenko | Curiosity was framed; | +| danilche@cs.umass.edu | Ignorance killed the cat. | +| CSCF | 5-4231 | -- Anonymous | + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 16:30:08 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 256AD4758F1 + for ; + Thu, 17 Apr 2003 16:30:07 -0400 (EDT) +Received: from mail.cs.umass.edu (loki.cs.umass.edu [128.119.243.168]) + by postgresql.org (Postfix) with ESMTP id 11A47475458 + for ; + Thu, 17 Apr 2003 16:30:04 -0400 (EDT) +Received: from phobos.cs.umass.edu (phobos.cs.umass.edu [128.119.243.161]) + by mail.cs.umass.edu (8.12.6/8.12.5) with ESMTP id h3HKU2jh030364 + (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT); + Thu, 17 Apr 2003 16:30:02 -0400 +Date: Thu, 17 Apr 2003 16:29:57 -0400 (EDT) +From: Victor Danilchenko +To: Stephan Szabo +Cc: pgsql-performance@postgresql.org +Subject: Re: Query speed problems +In-Reply-To: <20030417125211.J91312-100000@megazone23.bigpanda.com> +Message-ID: +References: <20030417125211.J91312-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Checked: This message probably not SPAM +X-Spam-Score: -32.2, Required: 5 +X-Spam-Tests: EMAIL_ATTRIBUTION, IN_REP_TO, QUOTED_EMAIL_TEXT, REFERENCES, + REPLY_WITH_QUOTES, USER_AGENT_PINE +X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com / mimedefang) +X-Spam-Status: No, hits=-38.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/162 +X-Sequence-Number: 1668 + +On Thu, 17 Apr 2003, Stephan Szabo wrote: + +> +>On Thu, 17 Apr 2003, Victor Danilchenko wrote: +> +>> The queries I have tested are as follows: +>> +>> SELECT DISTINCT maker.* FROM maker,model WHERE maker.id=model.maker +>> SELECT DISTINCT maker.* FROM maker join model ON maker.id=model.maker +>> +>> The point of the queries is to extract only the maker rows which +>> are referenced from the model table. I would happily use another way to +>> achieve the same end, should anyone suggest it. +> +>What does explain analyze show for the query? + +# explain analyze SELECT DISTINCT * FROM maker WHERE id=model.maker; +NOTICE: Adding missing FROM-clause entry for table "model" + QUERY PLAN +------------------------------------------------------------------------------------------------------------------------------------------ + Unique (cost=230.58..255.24 rows=123 width=171) (actual time=238.20..293.21 rows=128 loops=1) + -> Sort (cost=230.58..233.66 rows=1233 width=171) (actual time=238.19..241.07 rows=1233 loops=1) + Sort Key: maker.id, maker.fullname, maker.contact, maker.phone, maker.service_no, maker.lastuser, maker.comments + -> Merge Join (cost=0.00..167.28 rows=1233 width=171) (actual time=0.27..81.49 rows=1233 loops=1) + Merge Cond: ("outer".id = "inner".maker) + -> Index Scan using maker_pkey on maker (cost=0.00..52.00 rows=1000 width=164) (actual time=0.11..4.29 rows=137 loops=1) + -> Index Scan using makers on model (cost=0.00..94.28 rows=1233 width=7) (actual time=0.04..27.34 rows=1233 loops=1) + Total runtime: 295.30 msec +(8 rows) + + Following a suggestion sent in private mail, I have created an +index for model.maker column: + +# create index model_maker on model(maker); + + but that doesn't seem to have made an appreciable difference in +performance -- it's only about .05 seconds more than the above number if +I drop the index. + + Many thanks for your help. + +>> "maker" has only 137 rows, "model" only 1233 rows. I test the +>> performance in perl, by taking time right before and after query +>> execution. Executing the queries takes anywhere between .3 and .5 +>> seconds, depending on some other factors (removing the 'distinct' +>> keyword from the 1st query shaves about .1 second off of the execution +>> time for example). +> +>> Column | Type | Modifiers +>> ---------------+-----------------------+--------------------------------------------- +>> id | integer | not null default nextval('model_ids'::text) +>> name | character varying(20) | not null +>> maker | character varying(4) | +>> type_hardware | character varying(4) | +>> fullname | character varying(40) | +>> spec | character varying(50) | +>> lastuser | character varying(30) | +>> comments | text | +>> size_cap | character varying(10) | +>> Indexes: model_pkey primary key btree (id), +>> unique_model unique btree (name, maker, type_hardware) +>> Check constraints: "nonempty_fullname" (fullname > ''::character varying) +>> Foreign Key constraints: valid_maker FOREIGN KEY (maker) REFERENCES \ +>> maker(id) ON UPDATE NO ACTION ON DELETE NO ACTION, +>> valid_type FOREIGN KEY (type_hardware) +>> REFERENCES type_hardware(id) ON UPDATE NO ACTION ON DELETE NO ACTION +> +>Hmm, it doesn't look to me like model.maker= type queries are +>indexable with this set of things. An index on model(maker) might help. +> +> +>---------------------------(end of broadcast)--------------------------- +>TIP 4: Don't 'kill -9' the postmaster +> + +-- +| Victor Danilchenko | Curiosity was framed; | +| danilche@cs.umass.edu | Ignorance killed the cat. | +| CSCF | 5-4231 | -- Anonymous | + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 17:08:50 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 359204758F1 + for ; + Thu, 17 Apr 2003 17:08:50 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 82D4C475458 + for ; + Thu, 17 Apr 2003 17:08:49 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 2CA74D602; Thu, 17 Apr 2003 14:08:51 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 2253F5C03; Thu, 17 Apr 2003 14:08:51 -0700 (PDT) +Date: Thu, 17 Apr 2003 14:08:51 -0700 (PDT) +From: Stephan Szabo +To: Victor Danilchenko +Cc: +Subject: Re: Query speed problems +In-Reply-To: +Message-ID: <20030417140458.Q92220-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/163 +X-Sequence-Number: 1669 + +On Thu, 17 Apr 2003, Victor Danilchenko wrote: + +> Unique (cost=230.58..255.24 rows=123 width=171) (actual +> time=238.20..293.21 rows=128 loops=1) +> -> Sort (cost=230.58..233.66 rows=1233 width=171) (actual +> time=238.19..241.07 rows=1233 loops=1) +> Sort Key: maker.id, maker.fullname, maker.contact, +> maker.phone, maker.service_no, maker.lastuser, maker.comments +> -> Merge Join (cost=0.00..167.28 rows=1233 width=171) (actual +> time=0.27..81.49 rows=1233 loops=1) +> Merge Cond: ("outer".id = "inner".maker) +> -> Index Scan using maker_pkey on maker +> (cost=0.00..52.00 rows=1000 width=164) (actual time=0.11..4.29 +> rows=137 loops=1) +> -> Index Scan using makers on model (cost=0.00..94.28 +> rows=1233 width=7) (actual time=0.04..27.34 rows=1233 loops=1) +> Total runtime: 295.30 msec +> (8 rows) + +Hmm, well, for this version, it looks like most of the time is probably +going into the sort. I wonder if raising sort_mem would help this version +of the query (try a set sort_mem=8192; before running the query). This +isn't likely to get the time below like 160 msec though. + +> Following a suggestion sent in private mail, I have created an +> index for model.maker column: +> +> # create index model_maker on model(maker); +> +> but that doesn't seem to have made an appreciable difference in +> performance -- it's only about .05 seconds more than the above number if +> I drop the index. +Yeah, it looks like it's already using an index, but I didn't see that +index in the list of indexes on the table in the original mail, wierd. + + +From pgsql-performance-owner@postgresql.org Thu Apr 17 21:26:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2CD29475D91 + for ; + Thu, 17 Apr 2003 21:26:12 -0400 (EDT) +Received: from c001.snv.cp.net (h021.c001.snv.cp.net [209.228.32.135]) + by postgresql.org (Postfix) with SMTP id 5075D475ADE + for ; + Thu, 17 Apr 2003 21:26:11 -0400 (EDT) +Received: (cpmta 17407 invoked from network); 17 Apr 2003 18:26:13 -0700 +Received: from 209.228.32.129 (HELO mail.dilger.cc.criticalpath.net) + by smtp.register-admin.com (209.228.32.135) with SMTP; + 17 Apr 2003 18:26:13 -0700 +X-Sent: 18 Apr 2003 01:26:13 GMT +Received: from [216.68.146.219] by mail.dilger.cc with HTTP; + Thu, 17 Apr 2003 18:26:12 -0700 (PDT) +Content-Type: text/plain; charset=iso-8859-1 +Content-Disposition: inline +Content-Transfer-Encoding: 7bit +MIME-Version: 1.0 +To: danilche@cs.umass.edu +Cc: pgsql-performance@postgresql.org +From: "Nikolaus Dilger" +Subject: Re: Query speed problems +X-Sent-From: nikolaus@dilger.cc +Date: Thu, 17 Apr 2003 18:26:12 -0700 (PDT) +X-Mailer: Web Mail 5.3.0-6_sol28 +Message-Id: <20030417182613.4395.h015.c001.wm@mail.dilger.cc.criticalpath.net> +X-Spam-Status: No, hits=-13.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTE_TWICE_1 + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/164 +X-Sequence-Number: 1670 + +Victor, + +What is the issue? You get sub second response time. +Why waste your time trying to make it faster? +If you have a query that runs serveral minutes or hours +then its worthwhile tuning. Or if your query gets +executed several thausend times a day. + +Regards, +Nikolaus + +On Thu, 17 Apr 2003 15:17:01 -0400 (EDT), Victor +Danilchenko wrote: + +> +> Hi, +> +> In the process of developing an API for +> web/perl/postrgres +> interactions, I have come up against a peculiar +> problem; a rather simple +> query, run on two relatively small tables, takes as +> much as 0.4 seconds +> on my development system (it's a P2 266, which in this +> case is a good +> thing, as it exposes speed issues). I tried +> accomplishging the same +> thing via subqueries and joins, and both methods give +> me similarly bad +> result (join query is a little slower, but only a +> little). +> +> The queries I have tested are as follows: +> +> SELECT DISTINCT maker.* FROM maker,model WHERE +> maker.id=model.maker +> SELECT DISTINCT maker.* FROM maker join model ON +> maker.id=model.maker +> +> The point of the queries is to extract only the maker +> rows which +> are referenced from the model table. I would happily +> use another way to +> achieve the same end, should anyone suggest it. +> +> "maker" has only 137 rows, "model" only 1233 rows. I +> test the +> performance in perl, by taking time right before and +> after query +> execution. Executing the queries takes anywhere +between +> .3 and .5 +> seconds, depending on some other factors (removing the +> 'distinct' +> keyword from the 1st query shaves about .1 second off +> of the execution +> time for example). +> +> These execution times seem ridiculous. Any idea what +> the culprit +> may be? I hope it's not the text fields, 'cuz those +> fields are +> important. +> +> Both tables are quite simple: +> +> # \d maker +> Table "public.maker" +> Column | Type | Modifiers +> ------------+-----------------------+----------- +> id | character varying(4) | not null +> fullname | character varying(20) | +> contact | character varying(20) | +> phone | character varying(15) | +> service_no | character varying(20) | +> lastuser | character varying(30) | +> comments | text | +> Indexes: maker_pkey primary key btree (id) +> Triggers: RI_ConstraintTrigger_18881, +> RI_ConstraintTrigger_18882 +> +> # \d model +> Table "public.model" +> Column | Type | + +> Modifiers +> +---------------+-----------------------+--------------------------------------------- +> id | integer | not null +> default nextval('model_ids'::text) +> name | character varying(20) | not null +> maker | character varying(4) | +> type_hardware | character varying(4) | +> fullname | character varying(40) | +> spec | character varying(50) | +> lastuser | character varying(30) | +> comments | text | +> size_cap | character varying(10) | +> Indexes: model_pkey primary key btree (id), +> unique_model unique btree (name, maker, +> type_hardware) +> Check constraints: "nonempty_fullname" (fullname > +> ''::character varying) +> Foreign Key constraints: valid_maker FOREIGN KEY +> (maker) REFERENCES \ +> maker(id) ON UPDATE NO +> ACTION ON DELETE NO ACTION, +> valid_type FOREIGN KEY +> (type_hardware) +> REFERENCES type_hardware(id) ON UPDATE NO ACTION ON +> DELETE NO ACTION +> +> -- +> | Victor Danilchenko | Any sufficiently advanced + +> | +> | danilche@cs.umass.edu | technology is +> indistinguishable | +> | CSCF | 5-4231 | from a Perl script. + +> | +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the +> unregister command +> (send "unregister YourEmailAddressHere" to +> majordomo@postgresql.org) + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 01:11:35 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 9E4CE475ADE; Fri, 18 Apr 2003 01:11:34 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP + id C6430475458; Fri, 18 Apr 2003 01:11:33 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Thu, 17 Apr 2003 22:11:33 -0700 +Date: Thu, 17 Apr 2003 22:11:33 -0700 +From: Kevin Brown +To: pgsql-hackers@postgresql.org +Cc: pgsql-performance@postgresql.org +Subject: Foreign key performance +Message-ID: <20030418051133.GK1833@filer> +Mail-Followup-To: Kevin Brown , + pgsql-hackers@postgresql.org, pgsql-performance@postgresql.org +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-9.4 required=5.0 tests=BAYES_20,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/678 +X-Sequence-Number: 38168 + +I'm using 7.3.2 on Linux, with a decent amount of muscle behind it +(1.5 GHz PPro CPU, 1G mem, 20M/sec disks, xlog on different disk than +data). + +I've got a database that has several foreign keys, and I'm copying a +bunch of data from an MS-SQL server into it via Perl DBI. I noticed +that inserts into this database are very slow, on the order of 100 per +second on this hardware. All the inserts are happening in a single +transaction. The postmaster I'm connected to appears to be CPU +limited, as it's pegging the CPU at a constant 85 percent or more. + +I have no problem with that under normal circumstances (i.e., the +foreign key constraints are actively being enforced): it may well be +the nature of foreign keys, but the problem is this: all the keys are +DEFERRABLE INITIALLY DEFERRED and, on top of that, the Perl program +will SET CONSTRAINTS ALL DEFERRED at the beginning of the transaction. + +If I remove all the foreign key constraints, my performance goes up to +700 inserts per second! + +Why isn't the insert performance with all the constraints deferred +approximating that of the performance I get without the foreign keys?? +If anything, I should get a big delay at transaction commit time while +all the foreign key constraints are checked (and, indeed, I get that +too), but the performance during the transaction prior to the commit +should be the same as it is without the foreign key constraints. + +It's almost as if the foreign key constraints are being invoked and +the results ignored during the inserts... + +In essence, this smells like a bug to me, but I don't know enough +about the internals to really call it that. + + +Any ideas on what can be done about this? + + + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 01:30:51 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id ED2B5475ADE; Fri, 18 Apr 2003 01:30:49 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP + id 3184A475458; Fri, 18 Apr 2003 01:30:46 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id CDB7CD612; Thu, 17 Apr 2003 22:30:45 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id C36475C03; Thu, 17 Apr 2003 22:30:45 -0700 (PDT) +Date: Thu, 17 Apr 2003 22:30:45 -0700 (PDT) +From: Stephan Szabo +To: Kevin Brown +Cc: , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <20030418051133.GK1833@filer> +Message-ID: <20030417222628.G97462-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/679 +X-Sequence-Number: 38169 + +On Thu, 17 Apr 2003, Kevin Brown wrote: + +> I have no problem with that under normal circumstances (i.e., the +> foreign key constraints are actively being enforced): it may well be +> the nature of foreign keys, but the problem is this: all the keys are +> DEFERRABLE INITIALLY DEFERRED and, on top of that, the Perl program +> will SET CONSTRAINTS ALL DEFERRED at the beginning of the transaction. +> +> If I remove all the foreign key constraints, my performance goes up to +> 700 inserts per second! +> +> Why isn't the insert performance with all the constraints deferred +> approximating that of the performance I get without the foreign keys?? + +It appears (from some not terribly scientific experiments - see below) +that it's likely to be related to managing the deferred trigger queue +given that in my case at least running the constraints non-deferred was +negligible in comparison. + +On batch inserts to three tables each with a foreign key to a table +containing one row (and inserts of lots of that value), I saw a ratio of +approximately 1:1.7:7 for normal inserts:non-deferred fk:deferred fk on my +7.4 dev server. + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 02:06:08 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BB5B0476344 + for ; + Fri, 18 Apr 2003 02:06:07 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id E593E476342 + for ; + Fri, 18 Apr 2003 02:06:04 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3I664U6001967; + Fri, 18 Apr 2003 02:06:05 -0400 (EDT) +To: Stephan Szabo +Cc: Kevin Brown , pgsql-hackers@postgresql.org, + pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +In-reply-to: <20030417222628.G97462-100000@megazone23.bigpanda.com> +References: <20030417222628.G97462-100000@megazone23.bigpanda.com> +Comments: In-reply-to Stephan Szabo + message dated "Thu, 17 Apr 2003 22:30:45 -0700" +Date: Fri, 18 Apr 2003 02:06:04 -0400 +Message-ID: <1966.1050645964@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/683 +X-Sequence-Number: 38173 + +Stephan Szabo writes: +> It appears (from some not terribly scientific experiments - see below) +> that it's likely to be related to managing the deferred trigger queue +> given that in my case at least running the constraints non-deferred was +> negligible in comparison. + +At one time the deferred-trigger queue had an O(N^2) behavioral problem +for large N = number of pending trigger events. But I thought we'd +fixed that. What's the test case exactly? Can you get a profile with +gprof? + + regards, tom lane + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 02:25:23 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id CE704475ADE; Fri, 18 Apr 2003 02:25:21 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP + id 95BAD475458; Fri, 18 Apr 2003 02:25:20 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id D00B9D613; Thu, 17 Apr 2003 23:25:20 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id C5C805C03; Thu, 17 Apr 2003 23:25:20 -0700 (PDT) +Date: Thu, 17 Apr 2003 23:25:20 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + , +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <1966.1050645964@sss.pgh.pa.us> +Message-ID: <20030417231421.O97534-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/685 +X-Sequence-Number: 38175 + +On Fri, 18 Apr 2003, Tom Lane wrote: + +> Stephan Szabo writes: +> > It appears (from some not terribly scientific experiments - see below) +> > that it's likely to be related to managing the deferred trigger queue +> > given that in my case at least running the constraints non-deferred was +> > negligible in comparison. +> +> At one time the deferred-trigger queue had an O(N^2) behavioral problem +> for large N = number of pending trigger events. But I thought we'd +> fixed that. What's the test case exactly? Can you get a profile with +> gprof? + +I'm going to tomorrow hopefully - but it looks to me that we fixed one, but +possibly not another place where we read through the list unnecessarily +AFAICS. I think deferredTriggerInvokeEvents (when called with +immediate_only = true) is going to go through the entire list looking for +immediate triggers to fire after each statement. However, excepting set +constraints, any immediate triggers for any event added prior to this +statement will by necessity have already been run unless I'm missing +something, which means that we're often looking through entries that +aren't going to have any triggers to run now in any case. + +Keeping a pointer to the end of the list as of last statement and going +through the list from there cut the time for the deferred case in half in +my simple test (about 3.3x the no fk and just under 2x the immediate). + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 10:47:13 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 36464475E91 + for ; + Fri, 18 Apr 2003 10:47:12 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 7A4CE475458 + for ; + Fri, 18 Apr 2003 10:47:11 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 04455D619; Fri, 18 Apr 2003 07:47:15 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id EE18D5C02; Fri, 18 Apr 2003 07:47:15 -0700 (PDT) +Date: Fri, 18 Apr 2003 07:47:15 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <20030417231421.O97534-100000@megazone23.bigpanda.com> +Message-ID: <20030418073753.B1912-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/691 +X-Sequence-Number: 38181 + + +[Not sure this really is relevant for -performance at this point] + +On Thu, 17 Apr 2003, Stephan Szabo wrote: + +> On Fri, 18 Apr 2003, Tom Lane wrote: +> +> > Stephan Szabo writes: +> > > It appears (from some not terribly scientific experiments - see below) +> > > that it's likely to be related to managing the deferred trigger queue +> > > given that in my case at least running the constraints non-deferred was +> > > negligible in comparison. +> > +> > At one time the deferred-trigger queue had an O(N^2) behavioral problem +> > for large N = number of pending trigger events. But I thought we'd +> > fixed that. What's the test case exactly? Can you get a profile with +> > gprof? +> +> I'm going to tomorrow hopefully - but it looks to me that we fixed one, but + +Argh. I'm getting that state where gprof returns all 0s for times. I'm +pretty sure this has come up before along with how to get it to work, but +I couldn't find it in the archives. Someday I'll learn how to use gprof. :( + +In any case, the call list seemed reasonable. It's currently doing O(n^2) +calls to MemoryContextReset and deferredTriggerCheckState in InvokeEvents +I don't see anything else that's at that kind of number of calls (50 +million calls for a backend that's only done 10000 inserts stands out a +bit). Going only from last statement seems to make it linear (I think my +attempt is checking 1 too many trigger values, need to change that +probably). + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 10:51:38 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3E0FA475F39 + for ; + Fri, 18 Apr 2003 10:51:37 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 6A630475ECE + for ; + Fri, 18 Apr 2003 10:51:36 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3IEpeU6003991; + Fri, 18 Apr 2003 10:51:40 -0400 (EDT) +To: Stephan Szabo +Cc: Kevin Brown , pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +In-reply-to: <20030418073753.B1912-100000@megazone23.bigpanda.com> +References: <20030418073753.B1912-100000@megazone23.bigpanda.com> +Comments: In-reply-to Stephan Szabo + message dated "Fri, 18 Apr 2003 07:47:15 -0700" +Date: Fri, 18 Apr 2003 10:51:39 -0400 +Message-ID: <3990.1050677499@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/693 +X-Sequence-Number: 38183 + +Stephan Szabo writes: +> Argh. I'm getting that state where gprof returns all 0s for times. I'm +> pretty sure this has come up before along with how to get it to work, but +> I couldn't find it in the archives. Someday I'll learn how to use gprof. :( + +You're on Linux? You need to compile postmaster.c with -DLINUX_PROFILE. +But the call counts do sound pretty damning. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Fri Apr 18 11:01:26 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E2B3F475E91 + for ; + Fri, 18 Apr 2003 11:01:24 -0400 (EDT) +Received: from mail.cs.umass.edu (loki.cs.umass.edu [128.119.243.168]) + by postgresql.org (Postfix) with ESMTP id ACEA6475458 + for ; + Fri, 18 Apr 2003 11:01:23 -0400 (EDT) +Received: from phobos.cs.umass.edu (phobos.cs.umass.edu [128.119.243.161]) + by mail.cs.umass.edu (8.12.6/8.12.5) with ESMTP id h3IF1Qjh025960 + (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT); + Fri, 18 Apr 2003 11:01:26 -0400 +Date: Fri, 18 Apr 2003 11:01:18 -0400 (EDT) +From: Victor Danilchenko +To: Nikolaus Dilger +Cc: pgsql-performance@postgresql.org +Subject: Re: Query speed problems +In-Reply-To: + <20030417182613.4395.h015.c001.wm@mail.dilger.cc.criticalpath.net> +Message-ID: +References: <20030417182613.4395.h015.c001.wm@mail.dilger.cc.criticalpath.net> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Checked: This message probably not SPAM +X-Spam-Score: -28.9, Required: 5 +X-Spam-Tests: EMAIL_ATTRIBUTION, IN_REP_TO, REFERENCES, REPLY_WITH_QUOTES, + USER_AGENT_PINE +X-Scanned-By: MIMEDefang 2.30 (www . roaringpenguin . com / mimedefang) +X-Spam-Status: No, hits=-35.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/169 +X-Sequence-Number: 1675 + +On Thu, 17 Apr 2003, Nikolaus Dilger wrote: + +>Victor, +> +>What is the issue? You get sub second response time. + + The issue is that the query is a part of *user interface*, as I +wrote in my original message; and there is a small number of such +queries (about 3) that run per each user action. A second-long wait in +*UI* is unacceptable -- people tend to find even third-of-a-second wait +to be annoying. UI interactions should be so fast as to appear nearly +instant. + +>Why waste your time trying to make it faster? + + Well, there's also the learning aspect of it -- this is my first +major SQL project, and I am trying to understand as much as I can about +under-the-surface stuff. Thanks to Peter Darley, I already have a fast +solution -- now I simply want to understand more about the performance +issues inherent in reverse-lookup subqueries. + +>If you have a query that runs serveral minutes or hours +>then its worthwhile tuning. Or if your query gets +>executed several thausend times a day. + +-- +| Victor Danilchenko | Of course my password is the same as | +| danilche@cs.umass.edu | my pet's name. My macaw's name was | +| CSCF | 5-4231 | Q47pY!3, but I change it every 90 days. | + + +From pgsql-hackers-owner@postgresql.org Fri Apr 18 11:13:07 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B60E7475FFF + for ; + Fri, 18 Apr 2003 11:13:05 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id D84B4475458 + for ; + Fri, 18 Apr 2003 11:12:34 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id ADCA9D624; Fri, 18 Apr 2003 08:12:39 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 9F44B5C02; Fri, 18 Apr 2003 08:12:39 -0700 (PDT) +Date: Fri, 18 Apr 2003 08:12:39 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <3990.1050677499@sss.pgh.pa.us> +Message-ID: <20030418080950.R2132-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-25.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/695 +X-Sequence-Number: 38185 + + +On Fri, 18 Apr 2003, Tom Lane wrote: + +> Stephan Szabo writes: +> > Argh. I'm getting that state where gprof returns all 0s for times. I'm +> > pretty sure this has come up before along with how to get it to work, but +> > I couldn't find it in the archives. Someday I'll learn how to use gprof. :( +> +> You're on Linux? You need to compile postmaster.c with -DLINUX_PROFILE. + +Yep, thanks. :) + +> But the call counts do sound pretty damning. + +Yeah, but even with my hack last night it was still appreciably slower +than immediate constraints. Comparing the call counts in that function +for the immediate versus deferred(hacked) weren't giving me a good idea of +where that time was going. + + +From pgsql-performance-owner@postgresql.org Sat Apr 19 09:01:46 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 730B6475B85 + for ; + Sat, 19 Apr 2003 09:01:43 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id A7F6A4758C9 + for ; + Sat, 19 Apr 2003 09:01:42 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Sat, 19 Apr 2003 06:01:46 -0700 +Date: Sat, 19 Apr 2003 06:01:46 -0700 +From: Kevin Brown +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030419130146.GI1847@filer> +Mail-Followup-To: Kevin Brown , + pgsql-performance@postgresql.org +References: + <200304090918.45275.josh@agliodbs.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <200304090918.45275.josh@agliodbs.com> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/170 +X-Sequence-Number: 1676 + +Josh Berkus wrote: +> Denis, +> +> > Are you saying the 7.4 'group by' trick would be faster than the simple +> > select count(*)? That seems hard to believe, being that the request now has +> > to fetch / sort the data. I must be missing something. +> +> No, I'm saying that the 7.4 hash-aggregate is faster than the same query was +> under 7.2 or 7.3. Much faster. But it does little to speed up a raw +> count(*). +> +> > The kind of requests that I am really interested in are: +> > select count(*) from table where table.column like 'pattern%' +> +> > These seems to go much master on mysql (which I guess it not a MVCC +> > database? or wasn't the Innobase supposed to make it so?), +> +> They did incorporate a lot of MVCC logic into InnoDB tables, yes. +> Which means that if SELECT count(*) on an InnoDB table is just as +> fast as a MyISAM table, then it is not accurate. + +This is not necessarily true. The trigger-based approach to tracking +the current number of rows in a table might well be implemented +internally, and that may actually be much faster than doing it using +triggers (the performance losses you saw may well have been the result +of PG's somewhat poor trigger performance, and not the result of the +approach itself. It would be interesting to know how triggers effect +the performance of other databases). + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-performance-owner@postgresql.org Sat Apr 19 11:58:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5383F476182 + for ; + Sat, 19 Apr 2003 11:58:44 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 8FB9C476128 + for ; + Sat, 19 Apr 2003 11:58:43 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3JFwmU6021956; + Sat, 19 Apr 2003 11:58:48 -0400 (EDT) +To: Kevin Brown +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <20030419130146.GI1847@filer> +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> +Comments: In-reply-to Kevin Brown + message dated "Sat, 19 Apr 2003 06:01:46 -0700" +Date: Sat, 19 Apr 2003 11:58:48 -0400 +Message-ID: <21955.1050767928@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/171 +X-Sequence-Number: 1677 + +Kevin Brown writes: +> Josh Berkus wrote: +>> They did incorporate a lot of MVCC logic into InnoDB tables, yes. +>> Which means that if SELECT count(*) on an InnoDB table is just as +>> fast as a MyISAM table, then it is not accurate. + +> This is not necessarily true. The trigger-based approach to tracking +> the current number of rows in a table might well be implemented +> internally, and that may actually be much faster than doing it using +> triggers + +You missed the point of Josh's comment: in an MVCC system, the correct +COUNT() varies depending on which transaction is asking. Therefore it +is not possible for a centrally maintained row counter to give accurate +results to everybody, no matter how cheap it is to maintain. + +(The cheapness can be disputed as well, since it creates a single point +of contention for all inserts and deletes on the table. But that's a +different topic.) + + regards, tom lane + + +From pgsql-hackers-owner@postgresql.org Sat Apr 19 15:03:07 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D8757475F00 + for ; + Sat, 19 Apr 2003 15:03:06 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id D5F30475AA9 + for ; + Sat, 19 Apr 2003 15:03:01 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 4F5AFD60D; Sat, 19 Apr 2003 12:03:02 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 451555C03; Sat, 19 Apr 2003 12:03:02 -0700 (PDT) +Date: Sat, 19 Apr 2003 12:03:02 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <20030418080950.R2132-100000@megazone23.bigpanda.com> +Message-ID: <20030419114146.E18449-200000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: MULTIPART/MIXED; BOUNDARY="0-194152151-1050778982=:18449" +X-Spam-Status: No, hits=-13.0 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/716 +X-Sequence-Number: 38206 + + This message is in MIME format. The first part should be readable text, + while the remaining parts are likely unreadable without MIME-aware tools. + Send mail to mime@docserver.cac.washington.edu for more info. + +--0-194152151-1050778982=:18449 +Content-Type: TEXT/PLAIN; charset=US-ASCII + + +On Fri, 18 Apr 2003, Stephan Szabo wrote: + +> On Fri, 18 Apr 2003, Tom Lane wrote: +> +> > But the call counts do sound pretty damning. +> +> Yeah, but even with my hack last night it was still appreciably slower +> than immediate constraints. Comparing the call counts in that function +> for the immediate versus deferred(hacked) weren't giving me a good idea of +> where that time was going. + +This last was due to assert checking I think. AllocSetCheck was the big +time waster on the hacked deferred case. Turning off assert checking I +get: + +Median over 3 100000 inserts in one transaction (excepting the original +code which took a really long time so I ran it once) from time psql ... + +No Fk 24.14s +Immediate FK 42.80s +Original Deferred FK 1862.06s +Hacked Deferred FK 35.30s + +The hack was just the keeping around the list pointer from the last run +through (see attached - passed simple fk tests and regression, but there +might be problems I don't see). Looking at the code, I also wonder if we +would get some gain by not allocating the per_tuple_context at the +beginning but only when a non-deferred constraint is found since otherwise +we're creating and destroying the context and possibly never using it. +The cost would presumably be some boolean tests inside the inner loop. + +--0-194152151-1050778982=:18449 +Content-Type: TEXT/PLAIN; charset=US-ASCII; name="trigger.patch" +Content-Transfer-Encoding: BASE64 +Content-ID: <20030419120302.O18449@megazone23.bigpanda.com> +Content-Description: +Content-Disposition: attachment; filename="trigger.patch" + +KioqIHNyYy9iYWNrZW5kL2NvbW1hbmRzL3RyaWdnZXIuYwkyMDAzLTA0LTE5 +IDEyOjQxOjI0LjAwMDAwMDAwMCAtMDcwMA0KLS0tIHNyYy9iYWNrZW5kL2Nv +bW1hbmRzL3RyaWdnZXIuaGFjazEuYwkyMDAzLTA0LTE5IDEzOjQxOjE3LjAw +MDAwMDAwMCAtMDcwMA0KKioqKioqKioqKioqKioqDQoqKiogMTYyNiwxNjM3 +ICoqKioNCi0tLSAxNjI2LDE2NDMgLS0tLQ0KICAgKiBCZWNhdXNlIHRoaXMg +Y2FuIGdyb3cgcHJldHR5IGxhcmdlLCB3ZSBkb24ndCB1c2Ugc2VwYXJhdGUg 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from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 17DB94758C9 + for ; + Sat, 19 Apr 2003 15:04:08 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id B0767475EE2 + for ; + Sat, 19 Apr 2003 15:03:36 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2975053; Sat, 19 Apr 2003 12:03:32 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Tom Lane , Kevin Brown +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Sat, 19 Apr 2003 12:03:18 -0700 +User-Agent: KMail/1.4.3 +Cc: pgsql-performance@postgresql.org +References: + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> +In-Reply-To: <21955.1050767928@sss.pgh.pa.us> +MIME-Version: 1.0 +Message-Id: <200304191203.18634.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-31.6 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/172 +X-Sequence-Number: 1678 + +Kevin, Tom: + +> (The cheapness can be disputed as well, since it creates a single point +> of contention for all inserts and deletes on the table. But that's a +> different topic.) + +Actually, this was the problem with the trigger method of maintaining COUNT= +=20 +information in PostgreSQL. The statistics table itself becomes a=20 +significant souce of delay, since if a table_A gets 10,000 rows updated tha= +n=20 +table_count_A must necessarily be updated 10,000 times ... creating a lot o= +f=20 +dead tuples and severely attenuating the table on disk until the next vacuu= +m=20 +... resulting in Update #10,000 to table_count_A taking 100+ times as long = +as=20 +Update #1 does, due to the required random seek time on disk. + +I can personally think of two ways around this: + +In MySQL: store table_count_A as a non-MVCC table or global variable.=20=20 +Drawback: the count would not be accurate, as you would see changes due to= +=20 +incomplete transactions and eventually the count would be knocked off=20 +completely by an overload of multi-user activity. However, this does fit= +=20 +with MySQL's design philosophy of "Speed over accuracy", so I suspect that= +=20 +that's what they're doing. + +In PostgreSQL: +a) Put table_count_A on superfast media like a RAM card so that random seek= +s=20 +after 10,000 updates do not become a significant delay; +b) create an asynchronious table aggregates collector which would collect= +=20 +programmed statistics (like count(*) from table A) much in the same way tha= +t=20 +the planner statistics collector does. This would have the disadvantage of= +=20 +on being up to date when the database is idle, but the advantage of not=20 +imposing any significant overhead on Updates. + (Incidentally, I proposed this to one of my clients who complained about= +=20 +Postgres' slow aggregate performance, but they declined to fund the effort) + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Sat Apr 19 16:26:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6D410475AA9 + for ; + Sat, 19 Apr 2003 16:26:50 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 996404758C9 + for ; + Sat, 19 Apr 2003 16:26:49 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3JKQnU6023266; + Sat, 19 Apr 2003 16:26:49 -0400 (EDT) +To: Josh Berkus +Cc: Kevin Brown , + pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <200304191203.18634.josh@agliodbs.com> +References: + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <200304191203.18634.josh@agliodbs.com> +Comments: In-reply-to Josh Berkus + message dated "Sat, 19 Apr 2003 12:03:18 -0700" +Date: Sat, 19 Apr 2003 16:26:49 -0400 +Message-ID: <23265.1050784009@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.1 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/173 +X-Sequence-Number: 1679 + +Josh Berkus writes: +> In PostgreSQL: +> a) Put table_count_A on superfast media like a RAM card so that random seeks +> after 10,000 updates do not become a significant delay; + +As long as we're talking ugly, here ;-) + +You could use a sequence to hold the aggregate counter. A sequence +isn't transactional and so does not accumulate dead tuples. "setval()" +and "select last_value" should have constant-time performance. + + regards, tom lane + + +From pgsql-hackers-owner@postgresql.org Sat Apr 19 16:58:05 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 48E934758E6 + for ; + Sat, 19 Apr 2003 16:58:04 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id A62FB4758C9 + for ; + Sat, 19 Apr 2003 16:58:03 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3JKw2U6023462; + Sat, 19 Apr 2003 16:58:03 -0400 (EDT) +To: Stephan Szabo +Cc: Kevin Brown , pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +In-reply-to: <20030419114146.E18449-200000@megazone23.bigpanda.com> +References: <20030419114146.E18449-200000@megazone23.bigpanda.com> +Comments: In-reply-to Stephan Szabo + message dated "Sat, 19 Apr 2003 12:03:02 -0700" +Date: Sat, 19 Apr 2003 16:58:02 -0400 +Message-ID: <23461.1050785882@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/717 +X-Sequence-Number: 38207 + +Stephan Szabo writes: +> The hack was just the keeping around the list pointer from the last run +> through (see attached - passed simple fk tests and regression, but there +> might be problems I don't see). + +Shouldn't this patch update the comment in deferredTriggerInvokeEvents +(c. line 1860 in cvs tip)? + +> Looking at the code, I also wonder if we +> would get some gain by not allocating the per_tuple_context at the +> beginning but only when a non-deferred constraint is found since otherwise +> we're creating and destroying the context and possibly never using it. + +I doubt it's worth worrying over. Creation/destruction of a never-used +memory context is pretty cheap, I think. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sat Apr 19 21:13:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DF5524758E6 + for ; + Sat, 19 Apr 2003 21:13:34 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id AD96A4758C9 + for ; + Sat, 19 Apr 2003 21:13:33 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Sat, 19 Apr 2003 18:13:37 -0700 +Date: Sat, 19 Apr 2003 18:13:37 -0700 +From: Kevin Brown +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030420011336.GJ1847@filer> +Mail-Followup-To: Kevin Brown , + pgsql-performance@postgresql.org +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <21955.1050767928@sss.pgh.pa.us> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/174 +X-Sequence-Number: 1680 + +Tom Lane wrote: +> Kevin Brown writes: +> > Josh Berkus wrote: +> >> They did incorporate a lot of MVCC logic into InnoDB tables, yes. +> >> Which means that if SELECT count(*) on an InnoDB table is just as +> >> fast as a MyISAM table, then it is not accurate. +> +> > This is not necessarily true. The trigger-based approach to tracking +> > the current number of rows in a table might well be implemented +> > internally, and that may actually be much faster than doing it using +> > triggers +> +> You missed the point of Josh's comment: in an MVCC system, the correct +> COUNT() varies depending on which transaction is asking. Therefore it +> is not possible for a centrally maintained row counter to give accurate +> results to everybody, no matter how cheap it is to maintain. + +Hmm...true...but only if you really implement it as a faithful copy of +the trigger-based method. Implementing it on the backend brings some +advantages to the table, to wit: + +* The individual transactions don't need to update the + externally-visible count on every insert or delete, they only need + to update it at commit time. + +* The transaction can keep a count of the number of inserted and + deleted tuples it generates (on a per-table basis) during the life + of the transaction. The count value it returns to a client is the + count value it reads from the table that stores the count value plus + any differences that have been applied during the transaction. This + is fast, because the backend handling the transaction can keep this + difference value in its own private memory. + +* When a transaction commits, it only needs to apply the "diff value" + it stores internally to the external count value. + +Contention on the count value is only an issue if the external count +value is currently being written to by a transaction in the commit +phase. But the only time a transaction will be interested in reading +that value is when it's performing a count(*) operation or when it's +committing inserts/deletes that happened on the table in question (and +then only if the number of tuples inserted differs from the number +deleted). So the total amount of contention should be relatively low. + + +> (The cheapness can be disputed as well, since it creates a single point +> of contention for all inserts and deletes on the table. But that's a +> different topic.) + +That's true, but the single point of contention is only an issue at +transaction commit time (unless you're implementing READ UNCOMMITTED), +at least if you do something like what I described above. + + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-performance-owner@postgresql.org Sat Apr 19 23:34:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4BBE7475EE2 + for ; + Sat, 19 Apr 2003 23:34:27 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 70A714758C9 + for ; + Sat, 19 Apr 2003 23:34:19 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3K3YOU6024736; + Sat, 19 Apr 2003 23:34:24 -0400 (EDT) +To: Kevin Brown +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <20030420011336.GJ1847@filer> +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> +Comments: In-reply-to Kevin Brown + message dated "Sat, 19 Apr 2003 18:13:37 -0700" +Date: Sat, 19 Apr 2003 23:34:24 -0400 +Message-ID: <24735.1050809664@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/175 +X-Sequence-Number: 1681 + +Kevin Brown writes: +> Tom Lane wrote: +>> You missed the point of Josh's comment: in an MVCC system, the correct +>> COUNT() varies depending on which transaction is asking. Therefore it +>> is not possible for a centrally maintained row counter to give accurate +>> results to everybody, no matter how cheap it is to maintain. + +> Hmm...true...but only if you really implement it as a faithful copy of +> the trigger-based method. +> [ instead have transactions save up net deltas to apply at commit ] + +Good try, but it doesn't solve the problem. SERIALIZABLE transactions +should not see deltas applied by any transaction that commits after +they start. READ COMMITTED transactions can see such deltas --- but not +deltas applied since the start of their current statement. (And there +could be several different "current statements" with different snapshots +in progress in a single READ COMMITTED transaction.) + +AFAICS, central-counter techniques could only work in an MVCC system +if each transaction copies every counter in the system at each snapshot +freeze point, in case it finds itself needing that counter value later +on. This is a huge amount of mostly-useless overhead, and it makes the +problem of lock contention for access to the counters several orders of +magnitude worse than you'd first think. + +Of course you can dodge lots of this overhead if you're willing to +accept approximate answers. But I don't believe that central counters +are useful in an exact-MVCC-semantics system. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 02:28:54 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 80203475EE2 + for ; + Sun, 20 Apr 2003 02:28:53 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id 9C7C54758C9 + for ; + Sun, 20 Apr 2003 02:28:52 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Sat, 19 Apr 2003 23:28:52 -0700 +Date: Sat, 19 Apr 2003 23:28:52 -0700 +From: Kevin Brown +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030420062852.GK1847@filer> +Mail-Followup-To: Kevin Brown , + pgsql-performance@postgresql.org +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <24735.1050809664@sss.pgh.pa.us> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/176 +X-Sequence-Number: 1682 + +Tom Lane wrote: +> Kevin Brown writes: +> > Tom Lane wrote: +> >> You missed the point of Josh's comment: in an MVCC system, the correct +> >> COUNT() varies depending on which transaction is asking. Therefore it +> >> is not possible for a centrally maintained row counter to give accurate +> >> results to everybody, no matter how cheap it is to maintain. +> +> > Hmm...true...but only if you really implement it as a faithful copy of +> > the trigger-based method. +> > [ instead have transactions save up net deltas to apply at commit ] +> +> Good try, but it doesn't solve the problem. SERIALIZABLE transactions +> should not see deltas applied by any transaction that commits after +> they start. READ COMMITTED transactions can see such deltas --- but not +> deltas applied since the start of their current statement. (And there +> could be several different "current statements" with different snapshots +> in progress in a single READ COMMITTED transaction.) + +This is why I suspect the best way to manage this would be to manage +the counter itself using the MVCC mechanism (that is, you treat the +shared counter as a row in a table just like any other and, in fact, +it might be most beneficial for it to actually be exactly that), which +handles the visibility problem automatically. But I don't know how +much contention there would be as a result. + +> Of course you can dodge lots of this overhead if you're willing to +> accept approximate answers. But I don't believe that central counters +> are useful in an exact-MVCC-semantics system. + +No, but an MVCC-managed counter would be useful in such a system, +wouldn't it? Or am I missing something there, too (the deltas +themselves would be managed as described, and would be applied as +described)? + +So: how much contention would there be if the counter were managed in +exactly the same way as any row of a table is managed? Because I'm +not terribly familiar with how PG manages MVCC (pointers to +documentation on it welcomed) I can't answer that question myself. + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-hackers-owner@postgresql.org Sun Apr 20 02:56:57 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9F19047580B + for ; + Sun, 20 Apr 2003 02:56:56 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 265EE474E4F + for ; + Sun, 20 Apr 2003 02:56:56 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 83552D60D; Sat, 19 Apr 2003 23:56:56 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 790F45C03; Sat, 19 Apr 2003 23:56:56 -0700 (PDT) +Date: Sat, 19 Apr 2003 23:56:56 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <23461.1050785882@sss.pgh.pa.us> +Message-ID: <20030419235530.S23637-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/721 +X-Sequence-Number: 38211 + +On Sat, 19 Apr 2003, Tom Lane wrote: + +> Stephan Szabo writes: +> > The hack was just the keeping around the list pointer from the last run +> > through (see attached - passed simple fk tests and regression, but there +> > might be problems I don't see). +> +> Shouldn't this patch update the comment in deferredTriggerInvokeEvents +> (c. line 1860 in cvs tip)? + +Probably, since the second part of that is basically what this is. I'll +update and send updated patch tomorrow. + +> > Looking at the code, I also wonder if we +> > would get some gain by not allocating the per_tuple_context at the +> > beginning but only when a non-deferred constraint is found since otherwise +> > we're creating and destroying the context and possibly never using it. +> +> I doubt it's worth worrying over. Creation/destruction of a never-used +> memory context is pretty cheap, I think. + +Okay, sounds good enough for me. :) + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 06:07:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 66A76475D0F + for ; + Sun, 20 Apr 2003 06:07:49 -0400 (EDT) +Received: from smtp.web.de (smtp01.web.de [217.72.192.180]) + by postgresql.org (Postfix) with ESMTP id 9C8EC47580B + for ; + Sun, 20 Apr 2003 06:07:48 -0400 (EDT) +Received: from p50818c34.dip0.t-ipconnect.de ([80.129.140.52] helo=web.de) + by smtp.web.de with asmtp (TLSv1:RC4-MD5:128) (WEB.DE(Exim) 4.97 #53) + id 197Bji-0001Ux-00 + for pgsql-performance@postgresql.org; Sun, 20 Apr 2003 12:07:50 +0200 +Message-ID: <3EA27179.6010307@web.de> +Date: Sun, 20 Apr 2003 12:07:53 +0200 +From: Andreas Pflug +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> +In-Reply-To: <20030420062852.GK1847@filer> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-34.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,RCVD_IN_NJABL, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/177 +X-Sequence-Number: 1683 + +Kevin Brown wrote: + +> +>No, but an MVCC-managed counter would be useful in such a system, +>wouldn't it? Or am I missing something there, too (the deltas +>themselves would be managed as described, and would be applied as +>described)? +> +>So: how much contention would there be if the counter were managed in +>exactly the same way as any row of a table is managed? Because I'm +>not terribly familiar with how PG manages MVCC (pointers to +>documentation on it welcomed) I can't answer that question myself. +> +> +> +It looks to me that a "row number -1" really would solve this problem. + + I think a row counter on each table would be even useful for some kind +of auto-vacuum mechanism, that could be triggered if pg_class.reltuples +deviates too far from the real row count. Observing this mailing list, +missing or outdated statistics still seem to be a major source of +performance degradation. We all know these 1000 row estimates from +EXPLAIN, don't we? A default vacuum strategy for pgsql newbies should +solve a lot of those problems, preventing a lot of "pgsql is slow" threads. + +Regards, +Andreas + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 11:21:30 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 26FD1476355 + for ; + Sun, 20 Apr 2003 11:21:29 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 4C9A3476369 + for ; + Sun, 20 Apr 2003 11:21:28 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3KFLXU6026962; + Sun, 20 Apr 2003 11:21:33 -0400 (EDT) +To: Kevin Brown +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <20030420062852.GK1847@filer> +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> +Comments: In-reply-to Kevin Brown + message dated "Sat, 19 Apr 2003 23:28:52 -0700" +Date: Sun, 20 Apr 2003 11:21:32 -0400 +Message-ID: <26961.1050852092@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/178 +X-Sequence-Number: 1684 + +Kevin Brown writes: +> This is why I suspect the best way to manage this would be to manage +> the counter itself using the MVCC mechanism (that is, you treat the +> shared counter as a row in a table just like any other and, in fact, +> it might be most beneficial for it to actually be exactly that), which +> handles the visibility problem automatically. But I don't know how +> much contention there would be as a result. + +Hm. Contention probably wouldn't be the killer, since if transactions +don't try to update the count until they are about to commit, they won't +be holding the row lock for long. (You'd have to beware of deadlocks +between transactions that need to update multiple counters, but that +seems soluble.) What *would* be a problem is that such counter tables +would accumulate huge numbers of dead rows very quickly, making it +inefficient to find the live row. Josh already mentioned this as a +problem with user-trigger-based counting. You could stanch the bleeding +with sufficiently frequent vacuums, perhaps, but it just doesn't look +very appealing. + +Ultimately what this comes down to is "how much overhead are we willing +to load onto all other operations in order to make SELECT-COUNT(*)-with- +no-WHERE-clause fast"? Postgres has made a set of design choices that +favor the other operations. If you've designed an application that +lives or dies by fast COUNT(*), perhaps you should choose another +database. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 11:25:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BAFC7476315 + for ; + Sun, 20 Apr 2003 11:25:25 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 1D83A475FEE + for ; + Sun, 20 Apr 2003 11:25:25 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3KFPTU6027005; + Sun, 20 Apr 2003 11:25:29 -0400 (EDT) +To: Andreas Pflug +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <3EA27179.6010307@web.de> +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> <3EA27179.6010307@web.de> +Comments: In-reply-to Andreas Pflug + message dated "Sun, 20 Apr 2003 12:07:53 +0200" +Date: Sun, 20 Apr 2003 11:25:29 -0400 +Message-ID: <27004.1050852329@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/179 +X-Sequence-Number: 1685 + +Andreas Pflug writes: +> I think a row counter on each table would be even useful for some kind +> of auto-vacuum mechanism, that could be triggered if pg_class.reltuples +> deviates too far from the real row count. + +It would be counting the wrong thing. auto-vacuum needs to know how +many dead tuples are in a table, not how many live ones. Example: +UPDATE doesn't change the live-tuple count (without this property, +I don't think the sort of count maintenance Kevin is proposing could +possibly be efficient enough to be interesting). But it does create +a dead tuple that vacuum wants to know about. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 11:38:01 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 26874475CA9 + for ; + Sun, 20 Apr 2003 11:38:00 -0400 (EDT) +Received: from smtp.web.de (smtp03.web.de [217.72.192.158]) + by postgresql.org (Postfix) with ESMTP id 6E62747580B + for ; + Sun, 20 Apr 2003 11:37:59 -0400 (EDT) +Received: from p5081845f.dip0.t-ipconnect.de ([80.129.132.95] helo=web.de) + by smtp.web.de with asmtp (TLSv1:RC4-MD5:128) (WEB.DE(Exim) 4.97 #53) + id 197GtB-0001De-00; Sun, 20 Apr 2003 17:37:57 +0200 +Message-ID: <3EA2BED5.9010707@web.de> +Date: Sun, 20 Apr 2003 17:37:57 +0200 +From: Andreas Pflug +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3) Gecko/20030312 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> <3EA27179.6010307@web.de> + <27004.1050852329@sss.pgh.pa.us> +In-Reply-To: <27004.1050852329@sss.pgh.pa.us> +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-34.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,RCVD_IN_NJABL, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MOZILLA_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/180 +X-Sequence-Number: 1686 + +Tom Lane wrote: + +>It would be counting the wrong thing. auto-vacuum needs to know how +>many dead tuples are in a table, not how many live ones. Example: +>UPDATE doesn't change the live-tuple count (without this property, +>I don't think the sort of count maintenance Kevin is proposing could +>possibly be efficient enough to be interesting). But it does create +>a dead tuple that vacuum wants to know about. +> +> +> +I understand your point, but is this about VACUUM only or VACUUM ANALYZE +too? People wouldn't bother about big databases if it's still fast +(until the disk is full :-) + +Do dead tuples affect query planning? I thought the plan only cares +about existing rows and their data patterns. +So count(*), pg_stat_all_tables.n_tup_ins, .n_tup_upd and .n_tup_del all +together can make a VACUUM ANALYZE necessary, right? + +Regards, +Andreas + + +From pgsql-hackers-owner@postgresql.org Sun Apr 20 12:04:12 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 91361475CA9 + for ; + Sun, 20 Apr 2003 12:04:11 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 04EA647580B + for ; + Sun, 20 Apr 2003 12:04:07 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id D5AE0D611; Sun, 20 Apr 2003 09:04:10 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id C11865C03; Sun, 20 Apr 2003 09:04:10 -0700 (PDT) +Date: Sun, 20 Apr 2003 09:04:10 -0700 (PDT) +From: Stephan Szabo +To: Tom Lane +Cc: Kevin Brown , + +Subject: Re: [PERFORM] Foreign key performance +In-Reply-To: <20030419235530.S23637-100000@megazone23.bigpanda.com> +Message-ID: <20030420090304.F28973-200000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: MULTIPART/MIXED; BOUNDARY="0-176117628-1050854650=:28973" +X-Spam-Status: No, hits=-13.0 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/723 +X-Sequence-Number: 38213 + + This message is in MIME format. The first part should be readable text, + while the remaining parts are likely unreadable without MIME-aware tools. + Send mail to mime@docserver.cac.washington.edu for more info. + +--0-176117628-1050854650=:28973 +Content-Type: TEXT/PLAIN; charset=US-ASCII + +On Sat, 19 Apr 2003, Stephan Szabo wrote: + +> On Sat, 19 Apr 2003, Tom Lane wrote: +> +> > Stephan Szabo writes: +> > > The hack was just the keeping around the list pointer from the last run +> > > through (see attached - passed simple fk tests and regression, but there +> > > might be problems I don't see). +> > +> > Shouldn't this patch update the comment in deferredTriggerInvokeEvents +> > (c. line 1860 in cvs tip)? +> +> Probably, since the second part of that is basically what this is. I'll +> update and send updated patch tomorrow. + +Okay, this changes the second paragraph of that comment. I left in the +comment that's really similar next to where I actually do the selection of +which start point to use. + +--0-176117628-1050854650=:28973 +Content-Type: TEXT/PLAIN; charset=US-ASCII; name="trigger.patch" +Content-Transfer-Encoding: BASE64 +Content-ID: <20030420090410.N28973@megazone23.bigpanda.com> +Content-Description: +Content-Disposition: attachment; filename="trigger.patch" + +SW5kZXg6IHNyYy9iYWNrZW5kL2NvbW1hbmRzL3RyaWdnZXIuYw0KPT09PT09 +PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 +PT09PT09PT09PT09PT09PQ0KUkNTIGZpbGU6IC9wcm9qZWN0cy9jdnNyb290 +L3Bnc3FsLXNlcnZlci9zcmMvYmFja2VuZC9jb21tYW5kcy90cmlnZ2VyLmMs +dg0KcmV0cmlldmluZyByZXZpc2lvbiAxLjE0Nw0KZGlmZiAtYyAtcjEuMTQ3 +IHRyaWdnZXIuYw0KKioqIHNyYy9iYWNrZW5kL2NvbW1hbmRzL3RyaWdnZXIu +YwkyMDAzLzAzLzMxIDIwOjQ3OjUxCTEuMTQ3DQotLS0gc3JjL2JhY2tlbmQv +Y29tbWFuZHMvdHJpZ2dlci5jCTIwMDMvMDQvMjAgMTY6MDE6NTUNCioqKioq +KioqKioqKioqKg0KKioqIDE2MjYsMTYzNyAqKioqDQotLS0gMTYyNiwxNjQz 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+d2UgY2hhbmdlZCwgYnV0IGZvciBub3cgdGhpcyB3aWxsIGRvLg0KKyAJICov +DQorIAlkZWZ0cmlnX2V2ZW50c19pbW0gPSBOVUxMOw0KICANCiAgCS8qDQog +IAkgKiBTUUw5OSByZXF1aXJlcyB0aGF0IHdoZW4gYSBjb25zdHJhaW50IGlz +IHNldCB0byBJTU1FRElBVEUsIGFueQ0K + +--0-176117628-1050854650=:28973-- + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 12:46:06 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 10ED7475FBA + for ; + Sun, 20 Apr 2003 12:46:05 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 4AD82475F1C + for ; + Sun, 20 Apr 2003 12:46:04 -0400 (EDT) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 197HxC-0000yd-00 + for ; Sun, 20 Apr 2003 12:46:10 -0400 +Received: by dba2 (Postfix, from userid 1019) + id E1636CF3A; Sun, 20 Apr 2003 12:46:09 -0400 (EDT) +Date: Sun, 20 Apr 2003 12:46:09 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030420164609.GA30629@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> <26961.1050852092@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <26961.1050852092@sss.pgh.pa.us> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/181 +X-Sequence-Number: 1687 + +On Sun, Apr 20, 2003 at 11:21:32AM -0400, Tom Lane wrote: + +> favor the other operations. If you've designed an application that +> lives or dies by fast COUNT(*), perhaps you should choose another +> database. + +Or consider redesigning the application. The "no where clause" +restriction sure smacks of poor database normalisation to me. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-hackers-owner@postgresql.org Sun Apr 20 13:09:29 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CEA9C475CA9 + for ; + Sun, 20 Apr 2003 13:09:28 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 2BEB547580B + for ; + Sun, 20 Apr 2003 13:09:28 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3KH9OU6006997; + Sun, 20 Apr 2003 13:09:24 -0400 (EDT) +To: Stephan Szabo +Cc: Kevin Brown , pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +In-reply-to: <20030420090304.F28973-200000@megazone23.bigpanda.com> +References: <20030420090304.F28973-200000@megazone23.bigpanda.com> +Comments: In-reply-to Stephan Szabo + message dated "Sun, 20 Apr 2003 09:04:10 -0700" +Date: Sun, 20 Apr 2003 13:09:24 -0400 +Message-ID: <6996.1050858564@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/727 +X-Sequence-Number: 38217 + +Stephan Szabo writes: +> Okay, this changes the second paragraph of that comment. I left in the +> comment that's really similar next to where I actually do the selection of +> which start point to use. + +This had a bit of a problem yet: the loop in deferredTriggerInvokeEvents +expects 'prev_event' to point to the list entry just before 'event'. +A nice byproduct of fixing that is we don't uselessly rescan the last list +entry. I also tried to improve the comments a little. You can see what +I actually applied at +http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/trigger.c + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 14:09:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DA0C84763A4 + for ; + Sun, 20 Apr 2003 14:09:11 -0400 (EDT) +Received: from www.music.mcgill.ca (improv.Music.McGill.CA [132.206.141.14]) + by postgresql.org (Postfix) with ESMTP id 9DD83476366 + for ; + Sun, 20 Apr 2003 14:09:05 -0400 (EDT) +Received: from localhost (knopke@localhost) + by www.music.mcgill.ca (8.11.6/8.11.6) with ESMTP id h3KI95822015 + for ; Sun, 20 Apr 2003 14:09:05 -0400 +Date: Sun, 20 Apr 2003 14:09:05 -0400 (EDT) +From: Ian Knopke +To: pgsql-performance@postgresql.org +Subject: problems +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-12.3 required=5.0 tests=BAYES_01,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/182 +X-Sequence-Number: 1688 + +Hello, + +I'm not sure if this is really a problem. I'm working on a distributed web +crawling system which uses several clients on different machines. Results +are logged to a central Postgres system. When I start it, it works fine, +but seems to slow down drastically after several hours/days. To test the +database, I wrote a short Perl script which makes up random strings and +inserts them, and writes the benchmark times to a logfile. + +Comparing the beginning and end times from the log, it seems to take the +same amount of time to insert at the beginning of the process as after +about twenty minutes. However, I also logged the input from vmstat, which +shows the amount of memory available shrinking rapidly. + +Before running test program: + total used free shared buffers cached +Mem: 516136 120364 395772 0 4776 75884 +-/+ buffers/cache: 39704 476432 +Swap: 248996 0 248996 +procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- + r b swpd free buff cache si so bi bo in cs us sy id wa + 1 0 0 395768 4776 75888 0 0 124 27 124 236 13 2 86 0 + +The first 20 lines of vmstat output (3 seconds apart each, 512M total): +procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- + r b swpd free buff cache si so bi bo in cs us sy id wa + 3 0 0 267676 5116 194136 0 0 74 143 123 825 32 4 64 0 + 3 0 0 266244 5116 195532 0 0 0 0 105 2343 85 15 0 0 + 1 0 0 264816 5120 196932 0 0 0 0 104 2182 89 11 0 0 + 2 0 0 263324 5120 198308 0 0 0 299 126 2299 90 10 0 0 + 1 0 0 261856 5120 199744 0 0 0 0 101 2482 92 8 0 0 + 1 0 0 260376 5124 201188 0 0 1 683 114 2484 93 7 0 0 + 2 0 0 259152 5124 202392 0 0 0 640 119 2336 91 9 0 0 + 3 0 0 257880 5128 203628 0 0 0 0 102 2414 86 14 0 0 + 2 0 0 256772 5128 204712 0 0 0 640 116 2378 92 8 0 0 + + +Eventually the system moves to using swap and things really slow down. +Interestingly, when I stop the program and shut down postgres, only some +of the memory comes back. Here is the current state of my system with +postgres shut down, after running the test: procs +-----------memory---------- ---swap-- -----io---- --system-- ----cpu---- + r b swpd free buff cache si so bi bo in cs us sy id wa + 0 0 252 63396 5468 373792 0 0 29 318 133 1131 37 5 58 0 + +I seem to be missing some memory. However, I might not understand the +results from vmstat properly. Does anyone know what is going on or how I +can solve this? + +Ian Knopke + + + +Test program: +############################################################# +#!/usr/bin/perl -w +##test.pl - Program to test postgres performance + +use DBI; +use Time::HiRes qw(gettimeofday); +use IO::Socket; +use IO::File; +use Number::Format; + + +my $str='abcdefghijklmnopqrstuvwxyz'; +my @str=split('',$str); + + +$SIG{INT}=\&int_stoproutine; +open (LOGFILE,">testlog.txt") or die "Can't open logfile\n"; + +my $fmt=Number::Format->new(DECIMAL_DIGITS => 0); +my $dbh=DBI->connect("DBI:Pg:dbname=inserttests",,) or die "Can't connect: $DBI::errstr\n"; + +my $counter=0; +while(1) { + + my $starttime=gettimeofday(); + print LOGFILE "COUNTER: $counter "; + print LOGFILE "START: $starttime "; + my $str=&genmystr(); + print LOGFILE "STR: $str "; + my $donetime=gettimeofday(); + print LOGFILE "STRTIME: $donetime "; + + my $query_string="insert into tablea (tablea_term) values(\'$str\')"; + $sth=$dbh->prepare($query_string); + my $error_code=$sth->execute(); + + my $endtime=gettimeofday(); + print LOGFILE "END: $endtime "; + my $difftime=$endtime-$starttime; + print LOGFILE "DIFF: $difftime\n"; + $counter++; + +} + +close(LOGFILE); + +sub int_stoproutine { + exit; +} + +sub genmystr{ + my $str=''; + foreach(1 .. 8) { + + my $a=rand(25); + my $b=$fmt->round($a); + $str=$str.$str[$b]; + } + return $str; +} + + + + +-- + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 14:36:20 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 1C993475A80 + for ; + Sun, 20 Apr 2003 14:36:20 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 42A4B47580B + for ; + Sun, 20 Apr 2003 14:36:19 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3KIaAU6010083; + Sun, 20 Apr 2003 14:36:10 -0400 (EDT) +To: Ian Knopke +Cc: pgsql-performance@postgresql.org +Subject: Re: problems +In-reply-to: +References: +Comments: In-reply-to Ian Knopke + message dated "Sun, 20 Apr 2003 14:09:05 -0400" +Date: Sun, 20 Apr 2003 14:36:10 -0400 +Message-ID: <10082.1050863770@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/183 +X-Sequence-Number: 1689 + +Ian Knopke writes: +> Comparing the beginning and end times from the log, it seems to take the +> same amount of time to insert at the beginning of the process as after +> about twenty minutes. However, I also logged the input from vmstat, which +> shows the amount of memory available shrinking rapidly. + +AFAICT you are just showing us kernel disk cache expanding to fill +unused memory. This is normal and not a cause for alarm. + +> Eventually the system moves to using swap and things really slow down. + +Disk cache can't cause swapping --- the kernel will just throw away +cached pages when the memory is needed for something else. It could +be that you have growth in the number of Postgres processes, or the +sizes of individual processes, but vmstat isn't very helpful for +determining that (good ol' top would be more useful). In any case +you haven't actually shown us any data from the state where the system +is slow, so it's a bit hard to conjecture about what's going on. + +Some other important information that you haven't let us in on is the +platform and the Postgres version you're using. + + regards, tom lane + + +From pgsql-hackers-owner@postgresql.org Sun Apr 20 20:09:33 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9C802475A80 + for ; + Sun, 20 Apr 2003 20:09:31 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id DE3D147580B + for ; + Sun, 20 Apr 2003 20:09:30 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Sun, 20 Apr 2003 17:09:34 -0700 +Date: Sun, 20 Apr 2003 17:09:34 -0700 +From: Kevin Brown +To: pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +Message-ID: <20030421000933.GP1833@filer> +Mail-Followup-To: Kevin Brown , + pgsql-hackers@postgresql.org +References: <20030420090304.F28973-200000@megazone23.bigpanda.com> + <6996.1050858564@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <6996.1050858564@sss.pgh.pa.us> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/730 +X-Sequence-Number: 38220 + +Tom Lane wrote: +> Stephan Szabo writes: +> > Okay, this changes the second paragraph of that comment. I left in the +> > comment that's really similar next to where I actually do the selection of +> > which start point to use. +> +> This had a bit of a problem yet: the loop in deferredTriggerInvokeEvents +> expects 'prev_event' to point to the list entry just before 'event'. +> A nice byproduct of fixing that is we don't uselessly rescan the last list +> entry. I also tried to improve the comments a little. You can see what +> I actually applied at +> +> http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/trigger.c + +Any chance of backporting these changes to 7_3_STABLE (when you're +satisfied they don't break anything)? Just looking at the CVS log for +trigger.c, it appears there have been enough changes since then that +it might not be easy to do (and since it's not necessarily a "bug fix" +as such, it might not qualify for backporting to a stable version). + +Even if it's not something that can be put into another release of +7.3, it would certainly be useful to me. It might be useful to enough +people to justify releasing it as a patch on -patches, if nothing +else. + +I'd do it myself but I don't understand the trigger code at all (and +if there's any documentation you can point me to that describes the +various functions and supporting data structures in trigger.c, that +would help a lot), and I'd rather not touch something like that until +I understand it thoroughly. + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-hackers-owner@postgresql.org Sun Apr 20 20:35:00 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AE2B7475A80 + for ; + Sun, 20 Apr 2003 20:34:58 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 4E02C47580B + for ; + Sun, 20 Apr 2003 20:34:57 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3L0Z0U6021360; + Sun, 20 Apr 2003 20:35:00 -0400 (EDT) +To: Kevin Brown +Cc: pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +In-reply-to: <20030421000933.GP1833@filer> +References: <20030420090304.F28973-200000@megazone23.bigpanda.com> + <6996.1050858564@sss.pgh.pa.us> <20030421000933.GP1833@filer> +Comments: In-reply-to Kevin Brown + message dated "Sun, 20 Apr 2003 17:09:34 -0700" +Date: Sun, 20 Apr 2003 20:35:00 -0400 +Message-ID: <21359.1050885300@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/731 +X-Sequence-Number: 38221 + +Kevin Brown writes: +> Any chance of backporting these changes to 7_3_STABLE (when you're +> satisfied they don't break anything)? Just looking at the CVS log for +> trigger.c, it appears there have been enough changes since then that +> it might not be easy to do (and since it's not necessarily a "bug fix" +> as such, it might not qualify for backporting to a stable version). + +I'd be pretty hesitant to make such a change in the stable branch --- +at least not without a lot of testing. If you and others want to +provide such testing, go to it. The patch appears to apply cleanly +enough to 7.3, but here's an adjusted patch if fuzz makes you nervous... + + regards, tom lane + +*** trigger.c~ Sun Apr 20 20:28:55 2003 +--- trigger.c Sun Apr 20 20:29:13 2003 +*************** +*** 1461,1472 **** +--- 1461,1478 ---- + * Because this can grow pretty large, we don't use separate List nodes, + * but instead thread the list through the dte_next fields of the member + * nodes. Saves just a few bytes per entry, but that adds up. ++ * ++ * deftrig_events_imm holds the tail pointer as of the last ++ * deferredTriggerInvokeEvents call; we can use this to avoid rescanning ++ * entries unnecessarily. It is NULL if deferredTriggerInvokeEvents ++ * hasn't run since the last state change. + * + * XXX Need to be able to shove this data out to a file if it grows too + * large... + * ---------- + */ + static DeferredTriggerEvent deftrig_events; ++ static DeferredTriggerEvent deftrig_events_imm; + static DeferredTriggerEvent deftrig_event_tail; + + +*************** +*** 1680,1686 **** + deferredTriggerInvokeEvents(bool immediate_only) + { + DeferredTriggerEvent event, +! prev_event = NULL; + MemoryContext per_tuple_context; + Relation rel = NULL; + TriggerDesc *trigdesc = NULL; +--- 1686,1692 ---- + deferredTriggerInvokeEvents(bool immediate_only) + { + DeferredTriggerEvent event, +! prev_event; + MemoryContext per_tuple_context; + Relation rel = NULL; + TriggerDesc *trigdesc = NULL; +*************** +*** 1692,1704 **** + * are going to discard the whole event queue on return anyway, so no + * need to bother with "retail" pfree's. + * +! * In a scenario with many commands in a transaction and many +! * deferred-to-end-of-transaction triggers, it could get annoying to +! * rescan all the deferred triggers at each command end. To speed this +! * up, we could remember the actual end of the queue at EndQuery and +! * examine only events that are newer. On state changes we simply +! * reset the saved position to the beginning of the queue and process +! * all events once with the new states. + */ + + /* Make a per-tuple memory context for trigger function calls */ +--- 1698,1709 ---- + * are going to discard the whole event queue on return anyway, so no + * need to bother with "retail" pfree's. + * +! * If immediate_only is true, we need only scan from where the end of +! * the queue was at the previous deferredTriggerInvokeEvents call; +! * any non-deferred events before that point are already fired. +! * (But if the deferral state changes, we must reset the saved position +! * to the beginning of the queue, so as to process all events once with +! * the new states. See DeferredTriggerSetState.) + */ + + /* Make a per-tuple memory context for trigger function calls */ +*************** +*** 1709,1715 **** + ALLOCSET_DEFAULT_INITSIZE, + ALLOCSET_DEFAULT_MAXSIZE); + +! event = deftrig_events; + while (event != NULL) + { + bool still_deferred_ones = false; +--- 1714,1735 ---- + ALLOCSET_DEFAULT_INITSIZE, + ALLOCSET_DEFAULT_MAXSIZE); + +! /* +! * If immediate_only is true, then the only events that could need firing +! * are those since deftrig_events_imm. (But if deftrig_events_imm is +! * NULL, we must scan the entire list.) +! */ +! if (immediate_only && deftrig_events_imm != NULL) +! { +! prev_event = deftrig_events_imm; +! event = prev_event->dte_next; +! } +! else +! { +! prev_event = NULL; +! event = deftrig_events; +! } +! + while (event != NULL) + { + bool still_deferred_ones = false; +*************** +*** 1830,1835 **** +--- 1850,1858 ---- + /* Update list tail pointer in case we just deleted tail event */ + deftrig_event_tail = prev_event; + ++ /* Set the immediate event pointer for next time */ ++ deftrig_events_imm = prev_event; ++ + /* Release working resources */ + if (rel) + heap_close(rel, NoLock); +*************** +*** 1917,1922 **** +--- 1940,1946 ---- + MemoryContextSwitchTo(oldcxt); + + deftrig_events = NULL; ++ deftrig_events_imm = NULL; + deftrig_event_tail = NULL; + } + +*************** +*** 2146,2153 **** + * CONSTRAINTS command applies retroactively. This happens "for free" + * since we have already made the necessary modifications to the + * constraints, and deferredTriggerEndQuery() is called by +! * finish_xact_command(). + */ + } + + +--- 2170,2180 ---- + * CONSTRAINTS command applies retroactively. This happens "for free" + * since we have already made the necessary modifications to the + * constraints, and deferredTriggerEndQuery() is called by +! * finish_xact_command(). But we must reset deferredTriggerInvokeEvents' +! * tail pointer to make it rescan the entire list, in case some deferred +! * events are now immediately invokable. + */ ++ deftrig_events_imm = NULL; + } + + + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 20:46:30 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4C005475A80 + for ; + Sun, 20 Apr 2003 20:46:28 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id 4141347580B + for ; + Sun, 20 Apr 2003 20:46:27 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Sun, 20 Apr 2003 17:46:30 -0700 +Date: Sun, 20 Apr 2003 17:46:30 -0700 +From: Kevin Brown +To: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030421004630.GL1847@filer> +Mail-Followup-To: Kevin Brown , + pgsql-performance@postgresql.org +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> <26961.1050852092@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <26961.1050852092@sss.pgh.pa.us> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/184 +X-Sequence-Number: 1690 + +Tom Lane wrote: +> Kevin Brown writes: +> > This is why I suspect the best way to manage this would be to manage +> > the counter itself using the MVCC mechanism (that is, you treat the +> > shared counter as a row in a table just like any other and, in fact, +> > it might be most beneficial for it to actually be exactly that), which +> > handles the visibility problem automatically. But I don't know how +> > much contention there would be as a result. +> +> Hm. Contention probably wouldn't be the killer, since if transactions +> don't try to update the count until they are about to commit, they won't +> be holding the row lock for long. (You'd have to beware of deadlocks +> between transactions that need to update multiple counters, but that +> seems soluble.) What *would* be a problem is that such counter tables +> would accumulate huge numbers of dead rows very quickly, making it +> inefficient to find the live row. + +But that inefficiency is a problem for *all* oft-updated tables, is it +not? I know that you'll end up with an additional n tuples per +transaction (where n is the average number of tables inserted into or +deleted from per transaction), so this isn't an insignificant problem, +but it's one faced by any application that often updates a small +table. + +Causing a transaction which is already doing inserts/deletes to take +the hit of doing one additional update doesn't seem to me to be a +particularly large sacrifice, especially since the table it's updating +(the one that contains the counts) is likely to be cached in its +entirety. The chances are reasonable that the other activity the +transaction is performing will dwarf the additional effort that +maintaining the count demands. + +> Josh already mentioned this as a problem with user-trigger-based +> counting. + +Right, but the trigger based mechanism probably magnifies the issue by +orders of magnitude, and thus can't necessarily be used as an argument +against an internally-implemented method. + +> You could stanch the bleeding with sufficiently frequent vacuums, +> perhaps, but it just doesn't look very appealing. + +I would say this is more a strong argument for automatic VACUUM +management than against count management, because what you say here is +true of any oft-updated, oft-referenced table. + +> Ultimately what this comes down to is "how much overhead are we willing +> to load onto all other operations in order to make SELECT-COUNT(*)-with- +> no-WHERE-clause fast"? Postgres has made a set of design choices that +> favor the other operations. If you've designed an application that +> lives or dies by fast COUNT(*), perhaps you should choose another +> database. + +Or perhaps a mechanism similar to the one being discussed should be +implemented and controlled with a GUC variable, so instead of forcing +someone to choose another database you force them to choose between +the performance tradeoffs involved. We already give DBAs such choices +elsewhere, e.g. pg_stat_activity. + +The real question in all this is whether or not fast COUNT(*) +operations are needed often enough to even justify implementing a +mechanism to make them possible in PG. The question of getting fast +answers from COUNT(*) comes up often enough to be a FAQ, and that +suggests that there's enough demand for the feature that it may be +worth implementing just to shut those asking for it up. :-) + +Personally, I'd rather see such development effort go towards more +beneficial improvements, such as replication, 2PC, SQL/MED, etc. (or +even improving the efficiency of MVCC, since it was mentioned here as +a problem! :-). I consider COUNT(*) without a WHERE clause to be a +corner case, despite the frequency of questions about it. But I don't +think we should reject a patch to implement fast COUNT(*) just because +it represents a performance tradeoff, at least if it's GUC-controlled. + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-performance-owner@postgresql.org Sun Apr 20 21:53:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DC17D476315 + for ; + Sun, 20 Apr 2003 21:53:20 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 16495475A80 + for ; + Sun, 20 Apr 2003 21:53:17 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3L1rLU6021713; + Sun, 20 Apr 2003 21:53:21 -0400 (EDT) +To: Kevin Brown +Cc: pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +In-reply-to: <20030421004630.GL1847@filer> +References: + <200304090918.45275.josh@agliodbs.com> + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <20030420011336.GJ1847@filer> <24735.1050809664@sss.pgh.pa.us> + <20030420062852.GK1847@filer> <26961.1050852092@sss.pgh.pa.us> + <20030421004630.GL1847@filer> +Comments: In-reply-to Kevin Brown + message dated "Sun, 20 Apr 2003 17:46:30 -0700" +Date: Sun, 20 Apr 2003 21:53:20 -0400 +Message-ID: <21712.1050890000@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/185 +X-Sequence-Number: 1691 + +Kevin Brown writes: +> Personally, I'd rather see such development effort go towards more +> beneficial improvements, such as replication, 2PC, SQL/MED, etc. (or +> even improving the efficiency of MVCC, since it was mentioned here as +> a problem! :-). I consider COUNT(*) without a WHERE clause to be a +> corner case, despite the frequency of questions about it. + +Exactly. + +> But I don't +> think we should reject a patch to implement fast COUNT(*) just because +> it represents a performance tradeoff, at least if it's GUC-controlled. + +Well, this is moot since I see no one offering to provide such a patch. +But performance tradeoffs are only one of the costs involved. I suspect +any such mechanism would be invasive enough to represent a nontrivial +ongoing maintenance cost, whether anyone uses it or not. The extent +to which it munges core functionality would have to be a factor in +deciding whether to accept it. It'd take lots more thought than we've +expended in this thread to get an accurate handle on just what would +be involved... + +(BTW, if anyone actually is thinking about this, please make it a +per-table option not a global GUC option.) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Mon Apr 21 12:15:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EBFF64758C9 + for ; + Mon, 21 Apr 2003 12:15:13 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 63785474E42 + for ; + Mon, 21 Apr 2003 12:15:11 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2977665; Mon, 21 Apr 2003 09:15:13 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Kevin Brown , + pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Mon, 21 Apr 2003 09:14:43 -0700 +User-Agent: KMail/1.4.3 +References: + <26961.1050852092@sss.pgh.pa.us> <20030421004630.GL1847@filer> +In-Reply-To: <20030421004630.GL1847@filer> +MIME-Version: 1.0 +Message-Id: <200304210914.43552.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.2 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,QUOTE_TWICE_1, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/186 +X-Sequence-Number: 1692 + +Kevin, + +> > Josh already mentioned this as a problem with user-trigger-based +> > counting. +> +> Right, but the trigger based mechanism probably magnifies the issue by +> orders of magnitude, and thus can't necessarily be used as an argument +> against an internally-implemented method. + +I'm not sure about that, Kevin. The production trigger test was written i= +n C=20 +(by Joe Conway), using some of the best memory/efficiency management he cou= +ld=20 +devise. I could buy that the trigger mechanism adds a certain fixed=20 +overhead to the process, but not the contention that we were seeing ...=20 +especially not the geometric progression of inefficiency as the transaction= +=20 +count went up. We'll talk about this offlist; I may be able to get the=20 +client to authorize letting you examine the database. + +For further detail, our setup was sort of a "destruction test"; including: +1) a slightly underpowered server running too many processes; +2) a very high disk contention environment, with multiple applications=20 +fighting for I/O. +3) running COUNT(*), GROUP BY x on a table with 1.4 million rows, which was= +=20 +being updated in batches of 10,000 rows to 40,000 rows every few minutes. + +As I said before, the overhead for c-trigger based accounting, within the M= +VCC=20 +framework, was quite tolerable with small update batches, only 9-11% penalt= +y=20 +to the updates overall for batches of 100-300 updates. However, as we=20 +increased the application activity, the update penalty increased, up to=20 +40-45% with the full production load. + +It's not hard to figure out why; like most user's servers, the aggregate=20 +caching table was on the same disk as the table(s) being updated. The=20 +resut was a huge amount of disk-head-skipping between the updated table and= +=20 +the aggregate caching table every time a commit hit the database, with rand= +om=20 +seek times increasing the longer the time since the last VACUUM. + +Now, on a better server with these tables on fast RAID or on different=20 +spindles, I expect the result would be somewhat better. However, I also= +=20 +suspect that many of the users who complain the loudest about slow count(*)= +=20 +are operating in single-spindle environments. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 04:23:42 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 261404763A8 + for ; + Tue, 22 Apr 2003 04:23:39 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id DB2664763AF + for ; + Tue, 22 Apr 2003 04:23:37 -0400 (EDT) +Received: (qmail 37985 invoked by uid 1001); 22 Apr 2003 08:23:39 -0000 +Date: Tue, 22 Apr 2003 03:23:39 -0500 +From: "Jim C. Nasby" +To: Josh Berkus +Cc: Tom Lane , Kevin Brown , + pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Message-ID: <20030422032339.A37876@flake.decibel.org> +Reply-To: jim@nasby.net +References: + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <200304191203.18634.josh@agliodbs.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <200304191203.18634.josh@agliodbs.com>; + from josh@agliodbs.com on Sat, Apr 19, 2003 at 12:03:18PM -0700 +X-Operating-System: FreeBSD 4.7-RELEASE-p3 i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-39.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/187 +X-Sequence-Number: 1693 + +On Sat, Apr 19, 2003 at 12:03:18PM -0700, Josh Berkus wrote: +> Kevin, Tom: +> +> > (The cheapness can be disputed as well, since it creates a single point +> > of contention for all inserts and deletes on the table. But that's a +> > different topic.) +> +> Actually, this was the problem with the trigger method of maintaining COUNT +> information in PostgreSQL. The statistics table itself becomes a +> significant souce of delay, since if a table_A gets 10,000 rows updated than +> table_count_A must necessarily be updated 10,000 times ... creating a lot of +> dead tuples and severely attenuating the table on disk until the next vacuum +> ... resulting in Update #10,000 to table_count_A taking 100+ times as long as +> Update #1 does, due to the required random seek time on disk. + +Once statement level triggers are implimented, the performance would +probably be fine, assuming your update was a single statement. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 04:30:58 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A54C3475EFD + for ; + Tue, 22 Apr 2003 04:30:57 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 8BE19475EEE + for ; + Tue, 22 Apr 2003 04:30:56 -0400 (EDT) +Received: (qmail 38845 invoked by uid 1001); 22 Apr 2003 08:30:58 -0000 +Date: Tue, 22 Apr 2003 03:30:58 -0500 +From: "Jim C. Nasby" +To: "scott.marlowe" +Cc: Matthew Nuzum , + Pgsql-Performance +Subject: Re: choosing the right platform +Message-ID: <20030422033058.B37876@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030409185843.X31861@flake.decibel.org> + +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: ; + from scott.marlowe@ihs.com on Thu, Apr 10, 2003 at 10:42:35AM + -0600 +X-Operating-System: FreeBSD 4.7-RELEASE-p3 i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/188 +X-Sequence-Number: 1694 + +On Thu, Apr 10, 2003 at 10:42:35AM -0600, scott.marlowe wrote: +> The difference between SIZE and SHARE is the delta, which is only +> something like 3 or 4 megs for the initial select * from logs, but the +> second one is only 1 meg. On average, the actual increase in memory usage +> for postgresql isn't that great, usually about 1 meg. +> +> Running out of memory isn't really a problem with connections<=200 and 1 +> gig of ram, as long as sort_mem isn't too high. I/O contention is the +> killer at that point, as is CPU load. + +Except you should consider what you could be doing with that 200M, ie: +caching data. Even something as small as 1M per connection starts to add +up. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 04:33:33 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6D30E4763BE + for ; + Tue, 22 Apr 2003 04:33:32 -0400 (EDT) +Received: from houston.familyhealth.com.au (unknown [203.59.48.253]) + by postgresql.org (Postfix) with ESMTP id 4B9934763B6 + for ; + Tue, 22 Apr 2003 04:33:30 -0400 (EDT) +Received: (from root@localhost) + by houston.familyhealth.com.au (8.11.6p2/8.11.6) id h3M8XUc02874 + for pgsql-performance@postgresql.org; + Tue, 22 Apr 2003 16:33:30 +0800 (WST) + (envelope-from chriskl@familyhealth.com.au) +Received: from mariner (mariner.internal [192.168.0.101]) + by houston.familyhealth.com.au (8.11.6p2/8.9.3) with SMTP id + h3M8XQJ02649; Tue, 22 Apr 2003 16:33:26 +0800 (WST) +Message-ID: <024001c308a9$d8bd0f70$6500a8c0@fhp.internal> +From: "Christopher Kings-Lynne" +To: , "Josh Berkus" +Cc: "Tom Lane" , "Kevin Brown" , + +References: + <20030419130146.GI1847@filer> <21955.1050767928@sss.pgh.pa.us> + <200304191203.18634.josh@agliodbs.com> + <20030422032339.A37876@flake.decibel.org> +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +Date: Tue, 22 Apr 2003 16:33:27 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-scanner: scanned by Inflex 0.1.5c - (http://www.inflex.co.za/) +X-Spam-Status: No, hits=-12.8 required=5.0 + tests=BAYES_20,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/189 +X-Sequence-Number: 1695 + +> Once statement level triggers are implimented, the performance would +> probably be fine, assuming your update was a single statement. + +Statement triggers _are_ implemented in CVS. + +Chris + + +From pgsql-hackers-owner@postgresql.org Tue Apr 22 07:44:59 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EAF68475E14 + for ; + Tue, 22 Apr 2003 07:44:58 -0400 (EDT) +Received: from filer (12-234-86-219.client.attbi.com [12.234.86.219]) + by postgresql.org (Postfix) with ESMTP id 2E50C474E42 + for ; + Tue, 22 Apr 2003 07:44:27 -0400 (EDT) +Received: from localhost (localhost [127.0.0.1]) (uid 1000) + by filer with local; Tue, 22 Apr 2003 04:44:30 -0700 +Date: Tue, 22 Apr 2003 04:44:30 -0700 +From: Kevin Brown +To: pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +Message-ID: <20030422114429.GQ1833@filer> +Mail-Followup-To: Kevin Brown , + pgsql-hackers@postgresql.org +References: <20030420090304.F28973-200000@megazone23.bigpanda.com> + <6996.1050858564@sss.pgh.pa.us> <20030421000933.GP1833@filer> + <21359.1050885300@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +In-Reply-To: <21359.1050885300@sss.pgh.pa.us> +User-Agent: Mutt/1.4i +Organization: Frobozzco International +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/774 +X-Sequence-Number: 38264 + +Tom Lane wrote: +> Kevin Brown writes: +> > Any chance of backporting these changes to 7_3_STABLE (when you're +> > satisfied they don't break anything)? Just looking at the CVS log for +> > trigger.c, it appears there have been enough changes since then that +> > it might not be easy to do (and since it's not necessarily a "bug fix" +> > as such, it might not qualify for backporting to a stable version). +> +> I'd be pretty hesitant to make such a change in the stable branch --- +> at least not without a lot of testing. If you and others want to +> provide such testing, go to it. The patch appears to apply cleanly +> enough to 7.3, but here's an adjusted patch if fuzz makes you +> nervous... + +Thanks, Tom. I've applied the patch to my server and it has so far +passed the few tests I've thrown at it so far (it has detected foreign +key violations in both immediate and deferred trigger mode). And just +so you know, it performs FAR better than the pre-patched version does +-- in the overall transaction I'm doing, I see very little difference +now between deferred triggers and no triggers! + + +-- +Kevin Brown kevin@sysexperts.com + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 08:11:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9965E47638C + for ; + Tue, 22 Apr 2003 08:11:50 -0400 (EDT) +Received: from mail2.mediadesign.nl (md2.mediadesign.nl [212.19.205.67]) + by postgresql.org (Postfix) with SMTP id 5126A476373 + for ; + Tue, 22 Apr 2003 08:11:49 -0400 (EDT) +Received: (qmail 28210 invoked by uid 666); 22 Apr 2003 12:11:50 -0000 +Date: Tue, 22 Apr 2003 14:11:50 +0200 +From: Vincent van Leeuwen +To: pgsql-performance@postgresql.org +Subject: Re: the RAID question, again +Message-ID: <20030422121150.GU1836@md2.mediadesign.nl> +Mail-Followup-To: pgsql-performance@postgresql.org +References: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> +User-Agent: Mutt/1.3.28i +X-Spam-Status: No, hits=-38.0 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/190 +X-Sequence-Number: 1696 + +On 2003-04-16 19:32:54 -0700, Nikolaus Dilger wrote: +> One improvement area may be to put all 6 disks into a +> RAID 10 group. That way you have more I/O bandwith. + +A concern I have about that setup is that a large WAL write will have to wait +for 6 spindles to write the data before returning instead of 2 spindles. But +as you say it does create way more I/O bandwidth. I think I'll just test that +when the box is here instead of speculating further :) + +> One watchout is that the main memory of your machine +> may be better than the one of your RAID controller. +> The RAID controller has Integrated 128MB PC133 ECC +> SDRAM. You did not state what kind of memory your +> server has. +> + +On 2003-04-16 20:20:50 -0700, Josh Berkus wrote: +> Nickolaus has a good point. With a high-end Linux server, and a medium-end +> RAID card, it's sometimes faster to use Linux software RAID than harware +> raid. Not all the time, though. + +I've heard rumors that software raid performs poor when stacking raid layers +(raid 0 on raid 1). Not sure if that's still true though. My own experiences +with linux software raid (raid 5 on a low-cost fileserver for personal use) +are very good (especially in the reliability department, I've recovered from +two-disk failures due to controllers hanging up with only a few percent data +loss), although I've never been overly concerned with performance on that +setup so haven't really tested that. + +But if this controller is medium-end, could anyone recommend a high-end RAID +card that has excellent linux support? One of the things I especially like +about ICP Vortex products is the official linux support and the excellent +software utility for monitoring and (re)configuring the raid arrays. Comes in +handy when replacing hot-spares and rebuilding failed arrays while keeping +the box running :) + +Vincent van Leeuwen +Media Design - http://www.mediadesign.nl/ + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 13:19:41 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 232054758C9 + for ; + Tue, 22 Apr 2003 13:19:40 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 414D5474E42 + for ; + Tue, 22 Apr 2003 13:19:39 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2980227; Tue, 22 Apr 2003 10:19:35 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Vincent van Leeuwen , pgsql-performance@postgresql.org +Subject: Re: the RAID question, again +Date: Tue, 22 Apr 2003 10:18:57 -0700 +User-Agent: KMail/1.4.3 +References: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> + <20030422121150.GU1836@md2.mediadesign.nl> +In-Reply-To: <20030422121150.GU1836@md2.mediadesign.nl> +MIME-Version: 1.0 +Message-Id: <200304221018.58000.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.4 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_KMAIL autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/191 +X-Sequence-Number: 1697 + +Vincent, + +> But if this controller is medium-end, could anyone recommend a high-end +> RAID card that has excellent linux support? One of the things I especially +> like about ICP Vortex products is the official linux support and the +> excellent software utility for monitoring and (re)configuring the raid +> arrays. Comes in handy when replacing hot-spares and rebuilding failed +> arrays while keeping the box running :) + +No, just negative advice. Mylex support is dead until someone steps into t= +he=20 +shoes of the late developer of that driver. Adaptec is only paying their= +=20 +linux guy to do Red Hat support for their new RAID cards, so you're SOL wit= +h=20 +other distributions. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 13:34:57 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 661424763B1 + for ; + Tue, 22 Apr 2003 13:34:56 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 7F420476374 + for ; + Tue, 22 Apr 2003 13:34:54 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3MHYege000211; + Tue, 22 Apr 2003 11:34:40 -0600 (MDT) +Date: Tue, 22 Apr 2003 11:29:07 -0600 (MDT) +From: "scott.marlowe" +To: Vincent van Leeuwen +Cc: +Subject: Re: the RAID question, again +In-Reply-To: <20030422121150.GU1836@md2.mediadesign.nl> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-22.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/192 +X-Sequence-Number: 1698 + +On Tue, 22 Apr 2003, Vincent van Leeuwen wrote: + +> On 2003-04-16 19:32:54 -0700, Nikolaus Dilger wrote: +> > One improvement area may be to put all 6 disks into a +> > RAID 10 group. That way you have more I/O bandwith. +> +> A concern I have about that setup is that a large WAL write will have to wait +> for 6 spindles to write the data before returning instead of 2 spindles. But +> as you say it does create way more I/O bandwidth. I think I'll just test that +> when the box is here instead of speculating further :) + +Not in a RAID 10. Assuming the setup is: + +RAID0-0: disk0, disk1, disk2 +RAID0-1: disk3, disk4, disk5 +RAID1-0: RAID0-0, RAID0-1 + +Then a write would only have to wait on two disks. Assuming the physical +setup is one SCSI channel for RAID0-0 and one for RAID0-1, then both +drives can write at the same time and your write performance is virtually +identical to a single drive. + +> On 2003-04-16 20:20:50 -0700, Josh Berkus wrote: +> > Nickolaus has a good point. With a high-end Linux server, and a medium-end +> > RAID card, it's sometimes faster to use Linux software RAID than harware +> > raid. Not all the time, though. +> +> I've heard rumors that software raid performs poor when stacking raid layers +> (raid 0 on raid 1). Not sure if that's still true though. + +I tested it and was probably the one spreading the rumors. I was testing +on Linux kernels 2.4.9 at the time on a Dual PPro - 200 with 256 Meg RAM +and 6 Ultra Wide 4 gig SCSI drives at 10krpm. I've also tested other +setups. + +My experience was that RAID5 and RAID1 were no faster on top of RAID0 then +on bare drives. note that I didn't test for massive parallel +performance, which would probably have better performance with the extra +platters. I was testing something like 4 to 10 simo connects with pgbench +and my own queries, some large, some small. + + +> My own experiences +> with linux software raid (raid 5 on a low-cost fileserver for personal use) +> are very good (especially in the reliability department, I've recovered from +> two-disk failures due to controllers hanging up with only a few percent data +> loss), although I've never been overly concerned with performance on that +> setup so haven't really tested that. + +My experience with Linux RAID is similar to yours. It's always been rock +solid reliable, and acutally seems more intuitive to me now than any of +the hardware RAID cards I've played with. Plus you can FORCE it to do +what you want, whereas many cards refuse to do what you want. + +for really fast RAID, look at external RAID enclosures, that take x drives +and make them look like one great big drive. Good speed and easy to +manage, and to Linux it's just a big drive, so you don't need any special +drivers for it. + + +From pgsql-performance-owner@postgresql.org Tue Apr 22 13:45:27 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 67B644758C9 + for ; + Tue, 22 Apr 2003 13:45:26 -0400 (EDT) +Received: from isis.pcis.net (cr.pcis.net [207.18.226.3]) + by postgresql.org (Postfix) with ESMTP id 85CAE474E42 + for ; + Tue, 22 Apr 2003 13:44:55 -0400 (EDT) +Received: from lyric.ofsloans.com (unverified [209.180.142.225]) by + isis.pcis.net + (Rockliffe SMTPRA 4.5.6) with ESMTP id ; + Tue, 22 Apr 2003 12:45:03 -0500 +Subject: Re: the RAID question, again +From: Will LaShell +To: Josh Berkus +Cc: Vincent van Leeuwen , pgsql-performance@postgresql.org +In-Reply-To: <200304221018.58000.josh@agliodbs.com> +References: + <20030416193256.25788.h006.c001.wm@mail.dilger.cc.criticalpath.net> + <20030422121150.GU1836@md2.mediadesign.nl> + <200304221018.58000.josh@agliodbs.com> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-QFyN62ZClt2Ov0lS1CtF" +X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) +Date: 22 Apr 2003 10:44:48 -0700 +Message-Id: <1051033494.21231.11.camel@lyric.ofsloans.com> +Mime-Version: 1.0 +X-Spam-Status: No, hits=-45.1 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/193 +X-Sequence-Number: 1699 + +--=-QFyN62ZClt2Ov0lS1CtF +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +We use LSI Megaraid cards for all of our servers. Their older cards are +a bit dated now, but the new Elite 1650 is a pretty nice card. The +Adaptec cards are pretty hot, but as Josh has pointed out their +reference driver is for RedHat. Granted, that doesn't bother us here at +OFS because that's all we use on machine but to each their own. + +Sincerely, + +Will LaShell + +On Tue, 2003-04-22 at 10:18, Josh Berkus wrote: +> Vincent, +>=20 +> > But if this controller is medium-end, could anyone recommend a high-end +> > RAID card that has excellent linux support? One of the things I especia= +lly +> > like about ICP Vortex products is the official linux support and the +> > excellent software utility for monitoring and (re)configuring the raid +> > arrays. Comes in handy when replacing hot-spares and rebuilding failed +> > arrays while keeping the box running :) +>=20 +> No, just negative advice. Mylex support is dead until someone steps into= + the=20 +> shoes of the late developer of that driver. Adaptec is only paying thei= +r=20 +> linux guy to do Red Hat support for their new RAID cards, so you're SOL w= +ith=20 +> other distributions. +>=20 +> --=20 +> Josh Berkus +> Aglio Database Solutions +> San Francisco +>=20 +>=20 +> ---------------------------(end of broadcast)--------------------------- +> TIP 2: you can get off all lists at once with the unregister command +> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) + + +--=-QFyN62ZClt2Ov0lS1CtF +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.0.7 (GNU/Linux) + +iD8DBQA+pX+QZr3R5kgOZd0RAtLiAJwLZuD5ggeFAS0YLIrQdtRuzFQUrgCdFVvj +q6ggTUJqVGF7iDCOhI5/nAM= +=BfdI +-----END PGP SIGNATURE----- + +--=-QFyN62ZClt2Ov0lS1CtF-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 23 12:34:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 87E09475F16 + for ; + Wed, 23 Apr 2003 12:34:24 -0400 (EDT) +Received: from sabre.velocet.net (sabre.velocet.net [216.138.209.205]) + by postgresql.org (Postfix) with ESMTP id CC4A3474E42 + for ; + Wed, 23 Apr 2003 12:34:20 -0400 (EDT) +Received: from stark.dyndns.tv (H162.C233.tor.velocet.net [216.138.233.162]) + by sabre.velocet.net (Postfix) with ESMTP + id C331E138413; Wed, 23 Apr 2003 12:34:17 -0400 (EDT) +Received: from localhost ([127.0.0.1] helo=stark.dyndns.tv ident=foobar) + by stark.dyndns.tv with smtp (Exim 3.36 #1 (Debian)) + id 198NAN-0008NS-00; Wed, 23 Apr 2003 12:32:15 -0400 +To: Tom Lane +Cc: Kevin Brown , + pgsql-performance@postgresql.org +Subject: Re: [SQL] Yet Another (Simple) Case of Index not used +References: + <200304090918.45275.josh@agliodbs.com> <20030419130146.GI1847@filer> + <21955.1050767928@sss.pgh.pa.us> <20030420011336.GJ1847@filer> + <24735.1050809664@sss.pgh.pa.us> +In-Reply-To: <24735.1050809664@sss.pgh.pa.us> +From: Greg Stark +Organization: The Emacs Conspiracy; member since 1992 +Date: 23 Apr 2003 12:32:09 -0400 +Message-ID: <87adeh2n06.fsf@stark.dyndns.tv> +Lines: 17 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-38.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/194 +X-Sequence-Number: 1700 + + +Tom Lane writes: + +> AFAICS, central-counter techniques could only work in an MVCC system +> if each transaction copies every counter in the system at each snapshot +> freeze point, in case it finds itself needing that counter value later +> on. This is a huge amount of mostly-useless overhead, and it makes the +> problem of lock contention for access to the counters several orders of +> magnitude worse than you'd first think. + +Well, one option would be to do it in a lazy way. If you do an update on a +table with cached aggregate data just throw the data out. This way you get to +cache data on infrequently updated tables and get only a very small penalty on +frequently updated tables. + +-- +greg + + +From pgsql-performance-owner@postgresql.org Wed Apr 23 13:58:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7AF36476478 + for ; + Wed, 23 Apr 2003 13:55:45 -0400 (EDT) +Received: from tux.tuxee.net (tuxee.net [62.212.110.244]) + by postgresql.org (Postfix) with ESMTP id 54D7B476407 + for ; + Wed, 23 Apr 2003 13:53:57 -0400 (EDT) +Received: from mau.localdomain (mau.localdomain [192.168.1.10]) + by tux.tuxee.net (8.12.9/8.12.9) with ESMTP id h3NHrti3019870 + for ; Wed, 23 Apr 2003 19:53:55 +0200 +Received: from mau.localdomain (localhost [127.0.0.1]) + by mau.localdomain (8.12.8/8.12.6) with ESMTP id h3NHrtVo025025; + Wed, 23 Apr 2003 19:53:55 +0200 +Received: (from fred@localhost) + by mau.localdomain (8.12.8/8.12.8/Submit) id h3NHrt50025024; + Wed, 23 Apr 2003 19:53:55 +0200 +X-Authentication-Warning: mau.localdomain: fred set sender to + fred@jolliton.com using -f +To: pgsql-performance@postgresql.org +From: Frederic Jolliton +Subject: Important speed difference between a query and a function with the + same query +Date: Wed, 23 Apr 2003 19:53:55 +0200 +Message-ID: <8665p56qx8.fsf@mau.localdomain> +User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.3 +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-14.3 required=5.0 + tests=BAYES_01,USER_AGENT_GNUS_UA,X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/195 +X-Sequence-Number: 1701 + +Hi, + +(PostgreSQL 7.3.2 on i386-portbld-freebsd4.7, compiled by GCC 2.95.4) + +I've a curious performance problem with a function returning set of +rows. The query alone is very fast, but not when called from the +function. + +To "emulate" a parametred view=B9, I created a function as follow: + +CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info + AS '...' <- here the query show below, where 'LIMIT $1' is used instead= + of 'LIMIT 10' + LANGUAGE sql; + +The table table1 have 330K rows, and table2 have 3K rows. + +When I run the following query (prefixed with SELECT * to try to get +the same behavior that the second query), I obtain very good time. + +database=3D# SELECT * FROM ( + (SELECT a.field1,a.field2,a.field3,b.field3,b.field4,a.field5 + FROM table1 AS a, table1 AS b + WHERE a.field6=3Db.field4 + ORDER BY a.field6 DESC + LIMIT 10) + UNION + (SELECT a.field1,a.field2,b.field3,a.field3,a.field4,b.field5 + FROM table2 AS a, table1 AS b + WHERE a.field4=3Db.field6 + ORDER BY a.field4 DESC + LIMIT 10) + ORDER BY field4 DESC + LIMIT 10 +) AS type_get_info; + +[...] +(10 rows) + +Time: 185.86 ms + +But, when I run the function (with 10 as parameter, but even 1 is +slow) I get poor time: + +database=3D# SELECT * FROM get_info(10); +[...] +(10 rows) + +Time: 32782.26 ms +database=3D#=20 + +(even after a VACUUM FULL ANALYZE, and REINDEX of indexes used in the +queries) + +What is curious is that I remember that the function was fast at a +time.. + +What is the difference between the two case ? + +[1] Is there another solution to this 'hack' ? I can't simply create a +view and use 'LIMIT 10' because intermediate SELECT have be limited +too (to avoid UNION with 300K rows where only the first 10 are of +interest to me.) + +--=20 +Fr=E9d=E9ric Jolliton + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 11:47:53 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C1256476373 + for ; + Thu, 24 Apr 2003 11:47:51 -0400 (EDT) +Received: from tux.tuxee.net (tuxee.net [62.212.110.244]) + by postgresql.org (Postfix) with ESMTP id 90496476368 + for ; + Thu, 24 Apr 2003 11:47:48 -0400 (EDT) +Received: from mau.localdomain (mau.localdomain [192.168.1.10]) + by tux.tuxee.net (8.12.9/8.12.9) with ESMTP id h3OFlri3021850 + for ; Thu, 24 Apr 2003 17:47:53 +0200 +Received: from mau.localdomain (localhost [127.0.0.1]) + by mau.localdomain (8.12.8/8.12.6) with ESMTP id h3OFlrw7006919 + for ; Thu, 24 Apr 2003 17:47:53 +0200 +Received: (from fred@localhost) + by mau.localdomain (8.12.8/8.12.8/Submit) id h3OFlriH006918; + Thu, 24 Apr 2003 17:47:53 +0200 +X-Authentication-Warning: mau.localdomain: fred set sender to + fred@jolliton.com using -f +To: pgsql-performance@postgresql.org +From: Frederic Jolliton +Subject: Re: Important speed difference between a query and a +Date: Thu, 24 Apr 2003 17:47:53 +0200 +In-Reply-To: <8665p56qx8.fsf@mau.localdomain> (Frederic Jolliton's message + of "Wed, 23 Apr 2003 19:53:55 +0200") +Message-ID: <86el3rsxqu.fsf@mau.localdomain> +User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.3 +References: <8665p56qx8.fsf@mau.localdomain> +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.9 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA,X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/196 +X-Sequence-Number: 1702 + +> (PostgreSQL 7.3.2 on i386-portbld-freebsd4.7, compiled by GCC 2.95.4) +> +> I've a curious performance problem with a function returning set of +> rows. The query alone is very fast, but not when called from the +> function. +> +> To "emulate" a parametred view, I created a function as follow: +> +> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +> AS '...' <- here the query show below, where 'LIMIT $1' is used inste= +ad of 'LIMIT 10' +> LANGUAGE sql; + +Setting enable_seqscan to off give same result speed between the query +and the function ! + +So, the query in the function is not using index but the exact same +query alone does ! + +Is there an explanation ? + +--=20 +Fr=E9d=E9ric Jolliton + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 11:57:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 50478475E9D + for ; + Thu, 24 Apr 2003 11:57:02 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 79FB0474E42 + for ; + Thu, 24 Apr 2003 11:57:01 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3OFuuU6014132; + Thu, 24 Apr 2003 11:56:56 -0400 (EDT) +To: Frederic Jolliton +Cc: pgsql-performance@postgresql.org +Subject: Re: Important speed difference between a query and a +In-reply-to: <86el3rsxqu.fsf@mau.localdomain> +References: <8665p56qx8.fsf@mau.localdomain> <86el3rsxqu.fsf@mau.localdomain> +Comments: In-reply-to Frederic Jolliton + message dated "Thu, 24 Apr 2003 17:47:53 +0200" +Date: Thu, 24 Apr 2003 11:56:56 -0400 +Message-ID: <14131.1051199816@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/197 +X-Sequence-Number: 1703 + +Frederic Jolliton writes: +>> To "emulate" a parametred view, I created a function as follow: +>> +>> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +>> AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10' +>> LANGUAGE sql; + +> So, the query in the function is not using index but the exact same +> query alone does ! + +But it's not the same query, is it? With "LIMIT $1" the planner can't +know what the limit value is exactly, so it has to generate a plan that +won't be too unreasonable for either a small or a large limit. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 11:57:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 21055476368 + for ; + Thu, 24 Apr 2003 11:57:13 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id E67A9476361 + for ; + Thu, 24 Apr 2003 11:57:08 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id D0753D618; Thu, 24 Apr 2003 08:57:13 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id C5EE15C0A; Thu, 24 Apr 2003 08:57:13 -0700 (PDT) +Date: Thu, 24 Apr 2003 08:57:13 -0700 (PDT) +From: Stephan Szabo +To: Frederic Jolliton +Cc: +Subject: Re: Important speed difference between a query and a +In-Reply-To: <86el3rsxqu.fsf@mau.localdomain> +Message-ID: <20030424085451.P1362-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/198 +X-Sequence-Number: 1704 + + +On Thu, 24 Apr 2003, Frederic Jolliton wrote: + +> > (PostgreSQL 7.3.2 on i386-portbld-freebsd4.7, compiled by GCC 2.95.4) +> > +> > I've a curious performance problem with a function returning set of +> > rows. The query alone is very fast, but not when called from the +> > function. +> > +> > To "emulate" a parametred view, I created a function as follow: +> > +> > CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +> > AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10' +> > LANGUAGE sql; +> +> Setting enable_seqscan to off give same result speed between the query +> and the function ! +> +> So, the query in the function is not using index but the exact same +> query alone does ! +> +> Is there an explanation ? + +My guess is that limit $1 is assuming a larger number of rows when +planning the queries, large enough that it expects seqscan to be better +(assuming the limit is what it expects). It's probably not going to plan +that query each time the function is called so it's not going to know +whether you're calling with a small number (index scan may be better) or a +large number (seq scan may be better). For example, if you sent 100000, +the index scan might be a loser. + +Perhaps plpgsql with EXECUTE would work better for that, although it's +likely to have some general overhead. + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 12:33:32 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C63C7475E9D + for ; + Thu, 24 Apr 2003 12:33:31 -0400 (EDT) +Received: from tux.tuxee.net (tuxee.net [62.212.110.244]) + by postgresql.org (Postfix) with ESMTP id 93E13474E42 + for ; + Thu, 24 Apr 2003 12:33:30 -0400 (EDT) +Received: from mau.localdomain (mau.localdomain [192.168.1.10]) + by tux.tuxee.net (8.12.9/8.12.9) with ESMTP id h3OGXZi3023100 + for ; Thu, 24 Apr 2003 18:33:35 +0200 +Received: from mau.localdomain (localhost [127.0.0.1]) + by mau.localdomain (8.12.8/8.12.6) with ESMTP id h3OGXZw7007268 + for ; Thu, 24 Apr 2003 18:33:35 +0200 +Received: (from fred@localhost) + by mau.localdomain (8.12.8/8.12.8/Submit) id h3OGXZGP007267; + Thu, 24 Apr 2003 18:33:35 +0200 +X-Authentication-Warning: mau.localdomain: fred set sender to + fred@jolliton.com using -f +To: pgsql-performance@postgresql.org +From: Frederic Jolliton +Subject: Re: Important speed difference between a query and a +Date: Thu, 24 Apr 2003 18:33:35 +0200 +In-Reply-To: <14131.1051199816@sss.pgh.pa.us> (Tom Lane's message of "Thu, + 24 Apr 2003 11:56:56 -0400") +Message-ID: <86bryvsvmo.fsf@mau.localdomain> +User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.3 +References: <8665p56qx8.fsf@mau.localdomain> <86el3rsxqu.fsf@mau.localdomain> + <14131.1051199816@sss.pgh.pa.us> +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-40.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA, X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/199 +X-Sequence-Number: 1705 + +> Frederic Jolliton writes: +>>> To "emulate" a parametred view, I created a function as follow: +>>> +>>> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +>>> AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10' +>>> LANGUAGE sql; +> +>> So, the query in the function is not using index but the exact same +>> query alone does ! + +Tom Lane writes: +> But it's not the same query, is it? With "LIMIT $1" the planner can't +> know what the limit value is exactly, so it has to generate a plan that +> won't be too unreasonable for either a small or a large limit. + +Ok. So the query is optimized once and not each time.. I understand +now. + +But, since I "know" better that PostgreSQL that query must use index +in most of case, can I force in some manner the function when +declaring it to take this in account ? I suppose (not tested) that +setting enable_seqscan just before will probably do it, but what about +dump/restore of the database when recreating the function and keep +this "fix" automatically ? + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 12:41:47 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 86EF3476387 + for ; + Thu, 24 Apr 2003 12:41:45 -0400 (EDT) +Received: from tux.tuxee.net (tuxee.net [62.212.110.244]) + by postgresql.org (Postfix) with ESMTP id 39B4447637F + for ; + Thu, 24 Apr 2003 12:41:44 -0400 (EDT) +Received: from mau.localdomain (mau.localdomain [192.168.1.10]) + by tux.tuxee.net (8.12.9/8.12.9) with ESMTP id h3OGfni3023327 + for ; Thu, 24 Apr 2003 18:41:49 +0200 +Received: from mau.localdomain (localhost [127.0.0.1]) + by mau.localdomain (8.12.8/8.12.6) with ESMTP id h3OGfnw7007302 + for ; Thu, 24 Apr 2003 18:41:49 +0200 +Received: (from fred@localhost) + by mau.localdomain (8.12.8/8.12.8/Submit) id h3OGfnvr007301; + Thu, 24 Apr 2003 18:41:49 +0200 +X-Authentication-Warning: mau.localdomain: fred set sender to + fred@jolliton.com using -f +From: Frederic Jolliton +To: +Subject: Re: Important speed difference between a query and a +Date: Thu, 24 Apr 2003 18:41:49 +0200 +In-Reply-To: <20030424085451.P1362-100000@megazone23.bigpanda.com> (Stephan + Szabo's message of "Thu, 24 Apr 2003 08:57:13 -0700 (PDT)") +Message-ID: <868ytzsv8y.fsf@mau.localdomain> +User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.3 +References: <20030424085451.P1362-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-40.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA, X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/200 +X-Sequence-Number: 1706 + + +> On Thu, 24 Apr 2003, Frederic Jolliton wrote: +>> > CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +>> > AS '...' <- here the query show below, where 'LIMIT $1' is used in= +stead of 'LIMIT 10' +>> > LANGUAGE sql; +>> +>> Setting enable_seqscan to off give same result speed between the query +>> and the function ! +>> +>> So, the query in the function is not using index but the exact same +>> query alone does ! +>> +>> Is there an explanation ? + +Stephan Szabo writes: +> My guess is that limit $1 is assuming a larger number of rows when +> planning the queries, large enough that it expects seqscan to be +> better (assuming the limit is what it expects). It's probably not +> going to plan that query each time the function is called so it's +> not going to know whether you're calling with a small number (index +> scan may be better) or a large number (seq scan may be better). For +> example, if you sent 100000, the index scan might be a loser. +> +> Perhaps plpgsql with EXECUTE would work better for that, although +> it's likely to have some general overhead. + +The server is rather fast, and the query return 10 to 50 rows in most +case. So, this is probably a solution, even if it's not very +clean. (Well, I have to find an example to RETURN the result of +EXECUTE..) + +But, what I don't understand is why enable_seqscan change something if +the query is already planed. + +--=20 +Fr=E9d=E9ric Jolliton + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 13:28:12 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 462CD474E42 + for ; + Thu, 24 Apr 2003 13:28:11 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id CD877476083 + for ; + Thu, 24 Apr 2003 13:28:08 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id 91A41D618; Thu, 24 Apr 2003 10:28:08 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id 875255C0A; Thu, 24 Apr 2003 10:28:08 -0700 (PDT) +Date: Thu, 24 Apr 2003 10:28:08 -0700 (PDT) +From: Stephan Szabo +To: Frederic Jolliton +Cc: +Subject: Re: Important speed difference between a query and a +In-Reply-To: <868ytzsv8y.fsf@mau.localdomain> +Message-ID: <20030424101802.M2131-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/201 +X-Sequence-Number: 1707 + +On Thu, 24 Apr 2003, Frederic Jolliton wrote: + +> > On Thu, 24 Apr 2003, Frederic Jolliton wrote: +> > Perhaps plpgsql with EXECUTE would work better for that, although +> > it's likely to have some general overhead. +> +> The server is rather fast, and the query return 10 to 50 rows in most +> case. So, this is probably a solution, even if it's not very +> clean. (Well, I have to find an example to RETURN the result of +> EXECUTE..) + +Check out +http://techdocs.postgresql.org/guides/SetReturningFunctions + +specifically the GetRows() function for an example of using for in execute +with set returning functions. + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 13:40:21 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4961C476384 + for ; + Thu, 24 Apr 2003 13:40:20 -0400 (EDT) +Received: from tux.tuxee.net (tuxee.net [62.212.110.244]) + by postgresql.org (Postfix) with ESMTP id 08C92476387 + for ; + Thu, 24 Apr 2003 13:40:18 -0400 (EDT) +Received: from mau.localdomain (mau.localdomain [192.168.1.10]) + by tux.tuxee.net (8.12.9/8.12.9) with ESMTP id h3OHeHi3024945 + for ; Thu, 24 Apr 2003 19:40:17 +0200 +Received: from mau.localdomain (localhost [127.0.0.1]) + by mau.localdomain (8.12.8/8.12.6) with ESMTP id h3OHeHw7007694 + for ; Thu, 24 Apr 2003 19:40:17 +0200 +Received: (from fred@localhost) + by mau.localdomain (8.12.8/8.12.8/Submit) id h3OHeHqh007693; + Thu, 24 Apr 2003 19:40:17 +0200 +X-Authentication-Warning: mau.localdomain: fred set sender to + fred@jolliton.com using -f +To: +From: Frederic Jolliton +Subject: Re: Important speed difference between a query and a +Date: Thu, 24 Apr 2003 19:40:17 +0200 +In-Reply-To: <20030424101802.M2131-100000@megazone23.bigpanda.com> (Stephan + Szabo's message of "Thu, 24 Apr 2003 10:28:08 -0700 (PDT)") +Message-ID: <863ck7ssji.fsf@mau.localdomain> +User-Agent: Gnus/5.090015 (Oort Gnus v0.15) Emacs/21.3 +References: <20030424101802.M2131-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-40.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_GNUS_UA, X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/202 +X-Sequence-Number: 1708 + +> On Thu, 24 Apr 2003, Frederic Jolliton wrote: +[...] +>> The server is rather fast, and the query return 10 to 50 rows in +>> most case. So, this is probably a solution, even if it's not very +>> clean. (Well, I have to find an example to RETURN the result of +>> EXECUTE..) + +Stephan Szabo writes: +> Check out +> http://techdocs.postgresql.org/guides/SetReturningFunctions +> +> specifically the GetRows() function for an example of using for in +> execute with set returning functions. + +Oh right. Thanks you for pointing out this. + +--=20 +Fr=E9d=E9ric Jolliton + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 19:38:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 29063475458 + for ; + Thu, 24 Apr 2003 19:38:16 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 22B3C474E42 + for ; + Thu, 24 Apr 2003 19:38:15 -0400 (EDT) +Received: (qmail 70507 invoked by uid 1001); 24 Apr 2003 23:38:17 -0000 +Date: Thu, 24 Apr 2003 18:38:17 -0500 +From: "Jim C. Nasby" +To: pgsql-performance@postgresql.org +Subject: More tablescanning fun +Message-ID: <20030424183817.A66185@flake.decibel.org> +Reply-To: jim@nasby.net +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-13.5 required=5.0 + tests=BAYES_01,SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/203 +X-Sequence-Number: 1709 + +On this table + + project_id | integer | not null + id | integer | not null + date | date | not null + team_id | integer | not null + work_units | bigint | not null +Indexes: email_contrib_pkey primary key btree (project_id, id, date) + +with this breakdown of data + + project_id | count +------------+---------- + 5 | 56427141 + 8 | 1058843 + 24 | 361595 + 25 | 4092575 + 205 | 58512516 + +Any kind of operation on an entire project wants to tablescan, even +though it's going to take way longer. + +explain analyze select sum(work_units) from email_contrib where +project_id=8; + +Index scan 126, 56, 55 seconds +Seq. scan 1517, 850, 897 seconds + +It seems like the metrics used for the cost of index scanning v. table +scanning on large tables need to be revisited. It might be such a huge +difference in this case because the table is essentially clustered on +the primary key. I can test this by doing an aggregate for, say, a +specific team_id, which would be pretty well spread across the entire +table, but that'll have to wait a bit. + +Anyone have any thoughts on this? Also, is there a TODO to impliment +real clustered indexes? Doing stuff by project_id on this table in +sybase was very efficient, because there was a real clustered index on +the PK. By clustered index, I mean an index where the leaf nodes of the +B-tree were the actual table rows. This means the only overhead in going +through the index is scanning the branches, which in this case would be +pretty light-weight. + +Is this something that I should be using some PGSQL-specific feature +for, like inheritance? + +I've been really happy so far with PGSQL (comming from Sybase and DB2), +but it seems there's still some pretty big performance issues that want +to be addressed (or I should say performance issues that hurt really big +when you hit them :) ). +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Thu Apr 24 19:58:31 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D845C475458 + for ; + Thu, 24 Apr 2003 19:58:29 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 2874D474E42 + for ; + Thu, 24 Apr 2003 19:58:29 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3ONwUU6003661; + Thu, 24 Apr 2003 19:58:31 -0400 (EDT) +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +In-reply-to: <20030424183817.A66185@flake.decibel.org> +References: <20030424183817.A66185@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Thu, 24 Apr 2003 18:38:17 -0500" +Date: Thu, 24 Apr 2003 19:58:30 -0400 +Message-ID: <3660.1051228710@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/204 +X-Sequence-Number: 1710 + +"Jim C. Nasby" writes: +> It seems like the metrics used for the cost of index scanning v. table +> scanning on large tables need to be revisited. It might be such a huge +> difference in this case because the table is essentially clustered on +> the primary key. + +Probably. What does the correlation figure in pg_stats show as? + +There's been some previous debate about the equation used to correct +for correlation, which is certainly bogus (I picked it more or less +out of the air ;-)). But so far no one has proposed a replacement +equation with any better foundation ... take a look in +src/backend/optimizer/path/costsize.c if you want to get involved. + +> Also, is there a TODO to impliment +> real clustered indexes? + +No. It's not apparent to me how you could do that without abandoning +MVCC, which we're not likely to do. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 00:59:27 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0073D4758E6 + for ; + Fri, 25 Apr 2003 00:59:26 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id DB450474E42 + for ; + Fri, 25 Apr 2003 00:59:24 -0400 (EDT) +Received: (qmail 85793 invoked by uid 1001); 25 Apr 2003 04:59:24 -0000 +Date: Thu, 24 Apr 2003 23:59:24 -0500 +From: "Jim C. Nasby" +To: Tom Lane +Cc: pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +Message-ID: <20030424235924.B66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <3660.1051228710@sss.pgh.pa.us>; + from tgl@sss.pgh.pa.us on Thu, Apr 24, 2003 at 07:58:30PM -0400 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-40.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REFERENCES,REPLY_WITH_QUOTES, + SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/205 +X-Sequence-Number: 1711 + +On Thu, Apr 24, 2003 at 07:58:30PM -0400, Tom Lane wrote: +> "Jim C. Nasby" writes: +> > It seems like the metrics used for the cost of index scanning v. table +> > scanning on large tables need to be revisited. It might be such a huge +> > difference in this case because the table is essentially clustered on +> > the primary key. +> +> Probably. What does the correlation figure in pg_stats show as? + +stats=# select attname, correlation from pg_stats where +tablename='email_contrib'; + attname | correlation + ------------+------------- + project_id | 1 + id | 0.449204 + date | 0.271775 + team_id | 0.165588 + work_units | 0.0697928 + +> There's been some previous debate about the equation used to correct +> for correlation, which is certainly bogus (I picked it more or less +> out of the air ;-)). But so far no one has proposed a replacement +> equation with any better foundation ... take a look in +> src/backend/optimizer/path/costsize.c if you want to get involved. + +Are you reffering to the PF formula? + +> > Also, is there a TODO to impliment +> > real clustered indexes? +> +> No. It's not apparent to me how you could do that without abandoning +> MVCC, which we're not likely to do. + +Hmm... does MVCC mandate inserts go at the end? My understanding is that +each tuple indicates it's insert/last modified time; if this is the +case, why would a true clustered index break mvcc? I guess an update +that moves the tuple would be tricky, but I'm guesing there's some kind +of magic that could happen there... worst case would be adding an +'expired' timestamp. + +On the other hand, it might be possible to get the advantages of a +clustered index without doing a *true* clustered index. The real point +is to be able to use indexes; I've heard things like 'if you need to +access more than 10% of a table then using an index would be +disasterous', and that's not good... that number should really be over +50% for most reasonable ratios of fields indexed to fields in table (of +course field size plays a factor). +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 01:23:19 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5E1834758E6 + for ; + Fri, 25 Apr 2003 01:23:18 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 60938474E42 + for ; + Fri, 25 Apr 2003 01:23:13 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3P5NAU6013550; + Fri, 25 Apr 2003 01:23:10 -0400 (EDT) +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +In-reply-to: <20030424235924.B66185@flake.decibel.org> +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Thu, 24 Apr 2003 23:59:24 -0500" +Date: Fri, 25 Apr 2003 01:23:10 -0400 +Message-ID: <13549.1051248190@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/206 +X-Sequence-Number: 1712 + +"Jim C. Nasby" writes: +> On Thu, Apr 24, 2003 at 07:58:30PM -0400, Tom Lane wrote: +>> There's been some previous debate about the equation used to correct +>> for correlation, which is certainly bogus (I picked it more or less +>> out of the air ;-)). But so far no one has proposed a replacement +>> equation with any better foundation ... take a look in +>> src/backend/optimizer/path/costsize.c if you want to get involved. + +> Are you reffering to the PF formula? + +The PF formula is good as far as I know, but it assumes an uncorrelated +table order. The debate is how to correct it for nonzero correlation. +Specifically, this bit: + + * When the index ordering is exactly correlated with the table ordering + * (just after a CLUSTER, for example), the number of pages fetched should + * be just sT. What's more, these will be sequential fetches, not the + * random fetches that occur in the uncorrelated case. So, depending on + * the extent of correlation, we should estimate the actual I/O cost + * somewhere between s * T * 1.0 and PF * random_cost. We currently + * interpolate linearly between these two endpoints based on the + * correlation squared (XXX is that appropriate?). + +I believe the endpoints s*T and PF*random_cost, I think, but the curve +between them is anyone's guess. It's also quite possible that the +correlation stat that we currently compute is inadequate to model what's +going on. + +>> No. It's not apparent to me how you could do that without abandoning +>> MVCC, which we're not likely to do. + +> Hmm... does MVCC mandate inserts go at the end? + +Anywhere that there's free space. The point is that you can't promise +updates will fit on the same page as the original tuple. So whatever +desirable physical ordering you may have started with will surely +degrade over time. + +> On the other hand, it might be possible to get the advantages of a +> clustered index without doing a *true* clustered index. The real point +> is to be able to use indexes; I've heard things like 'if you need to +> access more than 10% of a table then using an index would be +> disasterous', and that's not good... that number should really be over +> 50% for most reasonable ratios of fields indexed to fields in table (of +> course field size plays a factor). + +If you have to read 50% of a table, you certainly should be doing a +linear scan. There will be hardly any pages you can skip (unless the +table is improbably well clustered), and the extra I/O needed to read +the index will buy you nothing. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 03:01:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9F26D4761C0 + for ; + Fri, 25 Apr 2003 03:01:43 -0400 (EDT) +Received: from fuji.krosing.net (unknown [194.204.44.118]) + by postgresql.org (Postfix) with ESMTP id 4DAD0476182 + for ; + Fri, 25 Apr 2003 03:01:42 -0400 (EDT) +Received: from fuji.krosing.net (lo [127.0.0.1]) + by fuji.krosing.net (8.12.8/8.12.8) with ESMTP id h3P71WmG003399; + Fri, 25 Apr 2003 10:01:32 +0300 +Received: (from hannu@localhost) + by fuji.krosing.net (8.12.8/8.12.8/Submit) id h3P71V5T003397; + Fri, 25 Apr 2003 10:01:31 +0300 +X-Authentication-Warning: fuji.krosing.net: hannu set sender to hannu@tm.ee + using -f +Subject: Re: Important speed difference between a query and a +From: Hannu Krosing +To: Frederic Jolliton +Cc: pgsql-performance@postgresql.org +In-Reply-To: <86bryvsvmo.fsf@mau.localdomain> +References: <8665p56qx8.fsf@mau.localdomain> + <86el3rsxqu.fsf@mau.localdomain> <14131.1051199816@sss.pgh.pa.us> + <86bryvsvmo.fsf@mau.localdomain> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Organization: +Message-Id: <1051254090.2997.3.camel@fuji.krosing.net> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.4 +Date: 25 Apr 2003 10:01:31 +0300 +X-Spam-Status: No, hits=-33.7 required=5.0 + tests=BAYES_01,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_XIMIAN,X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/207 +X-Sequence-Number: 1713 + +Frederic Jolliton kirjutas N, 24.04.2003 kell 19:33: +> > Frederic Jolliton writes: +> >>> To "emulate" a parametred view, I created a function as follow: +> >>> +> >>> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +> >>> AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10' +> >>> LANGUAGE sql; +> > +> >> So, the query in the function is not using index but the exact same +> >> query alone does ! +> +> Tom Lane writes: +> > But it's not the same query, is it? With "LIMIT $1" the planner can't +> > know what the limit value is exactly, so it has to generate a plan that +> > won't be too unreasonable for either a small or a large limit. +> +> Ok. So the query is optimized once and not each time.. I understand +> now. +> +> But, since I "know" better that PostgreSQL that query must use index +> in most of case, can I force in some manner the function when +> declaring it to take this in account ? + +You could define two functions - one for small sets with constant LIMITs +(maybe 50) in UNION parts, and another with $1. Then use accordingly. + +> I suppose (not tested) that +> setting enable_seqscan just before will probably do it, but what about +> dump/restore of the database when recreating the function and keep +> this "fix" automatically ? + +------------- +Hannu + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 10:38:04 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5075B4762F1 + for ; + Fri, 25 Apr 2003 10:38:03 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id A380F4762CF + for ; + Fri, 25 Apr 2003 10:37:58 -0400 (EDT) +Received: (qmail 8589 invoked by uid 1001); 25 Apr 2003 14:38:01 -0000 +Date: Fri, 25 Apr 2003 09:38:01 -0500 +From: "Jim C. Nasby" +To: Tom Lane +Cc: pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +Message-ID: <20030425093800.C66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> + <13549.1051248190@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <13549.1051248190@sss.pgh.pa.us>; + from tgl@sss.pgh.pa.us on Fri, Apr 25, 2003 at 01:23:10AM -0400 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-39.2 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REFERENCES,REPLY_WITH_QUOTES, + SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/208 +X-Sequence-Number: 1714 + +On Fri, Apr 25, 2003 at 01:23:10AM -0400, Tom Lane wrote: +> I believe the endpoints s*T and PF*random_cost, I think, but the curve +> between them is anyone's guess. It's also quite possible that the +> correlation stat that we currently compute is inadequate to model what's +> going on. + +In this case, the interpolation can't be at fault, because correlation +is 1 (unless the interpolation is backwards, but that doesn't appear to +be the case). + +One possibility is that IndexSelectivity isn't taking +most_common_(vals|freqs) into account. + +Looking at this from an idea case, most (or all) of this query should be +retrieved by simply incrementing through both the index and the tuples +at the same time. We should end up pulling 0.7% of the index and raw +pages combined. Analyze thinks that using the index will be about 50% +more expensive, though. (3258557 v. 2274866) + +A thought that comes to mind here is that it would be incredible if +pgsql could take metrics of how long things actually take on a live +system and incorporate them... basically learning as it goes. A first +step in this case would be to keep tabs on how close real page-read +counts come to what the optimizer predicted, and storing that for later +analysis. This would make it easier for you to verify your linear +correlation assumption, for example (it'd also make it easier to +validate the PF formula). + +> >> No. It's not apparent to me how you could do that without abandoning +> >> MVCC, which we're not likely to do. +> +> > Hmm... does MVCC mandate inserts go at the end? +> +> Anywhere that there's free space. The point is that you can't promise +> updates will fit on the same page as the original tuple. So whatever +> desirable physical ordering you may have started with will surely +> degrade over time. + +Yes, updates are the tricky part to clustered indexes, and MVCC might +make it harder. What Sybase 11 (which only supports page locking) does +is see if the update moves the tuple off it's current page. If it +doesn't, it just shuffles the page around as needed and goes on with +business. If it needs to move, it grabs (and locks) the page it needs to +move to, inserts it on that page (possibly incurring a page split), and +deletes it from the old page. My guess is that with MVCC, you can't +simply delete the old tuple... you'd have to leave some kind of 'bread +crumb' behind for older transactions to see (though, I guess this would +already have to be happening somehow). + +The reason to do this in this case is well worth it though... we end up +with one table (simplifies code) that should essentially act as if it +was multiple (5 in this case) tables, so performance should still be +very good. + +> > On the other hand, it might be possible to get the advantages of a +> > clustered index without doing a *true* clustered index. The real point +> > is to be able to use indexes; I've heard things like 'if you need to +> > access more than 10% of a table then using an index would be +> > disasterous', and that's not good... that number should really be over +> > 50% for most reasonable ratios of fields indexed to fields in table (of +> > course field size plays a factor). +> +> If you have to read 50% of a table, you certainly should be doing a +> linear scan. There will be hardly any pages you can skip (unless the +> table is improbably well clustered), and the extra I/O needed to read +> the index will buy you nothing. + +Yes, and it's that 'improbably well clustered' case that I have here. :) +But even if you're only 25% clustered, I think you'll still see a huge +gain on a very large table, especially if the index tuples are +substantially smaller than the raw tuples (which they normally should +be). +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 11:09:08 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7794D475F16 + for ; + Fri, 25 Apr 2003 11:09:06 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 99B9D47636C + for ; + Fri, 25 Apr 2003 11:09:00 -0400 (EDT) +Received: (qmail 9776 invoked by uid 1001); 25 Apr 2003 15:09:05 -0000 +Date: Fri, 25 Apr 2003 10:09:05 -0500 +From: "Jim C. Nasby" +To: Frederic Jolliton +Cc: pgsql-performance@postgresql.org +Subject: Re: Important speed difference between a query and a function with + the same query +Message-ID: <20030425100905.D66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <8665p56qx8.fsf@mau.localdomain> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <8665p56qx8.fsf@mau.localdomain>; + from fred-pg@jolliton.com on Wed, Apr 23, 2003 at 07:53:55PM +0200 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/209 +X-Sequence-Number: 1715 + +On Wed, Apr 23, 2003 at 07:53:55PM +0200, Frederic Jolliton wrote: +> CREATE FUNCTION get_info (integer) RETURNS SETOF type_get_info +> AS '...' <- here the query show below, where 'LIMIT $1' is used instead of 'LIMIT 10' +> LANGUAGE sql; + +You should probably define the function to be STABLE. + + LANGUAGE sql STABLE; + +See +http://www.postgresql.org/docs/view.php?version=7.3&idoc=1&file=sql-createfunction.html +for more info. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 12:28:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0DAAB475E77 + for ; + Fri, 25 Apr 2003 12:28:35 -0400 (EDT) +Received: from fuji.krosing.net (sein.itera.ee [194.126.109.126]) + by postgresql.org (Postfix) with ESMTP id 0C922474E42 + for ; + Fri, 25 Apr 2003 12:28:34 -0400 (EDT) +Received: from fuji.krosing.net (lo [127.0.0.1]) + by fuji.krosing.net (8.12.8/8.12.8) with ESMTP id h3PGSIJ0002719; + Fri, 25 Apr 2003 19:28:18 +0300 +Received: (from hannu@localhost) + by fuji.krosing.net (8.12.8/8.12.8/Submit) id h3PGS6Ss002717; + Fri, 25 Apr 2003 19:28:06 +0300 +X-Authentication-Warning: fuji.krosing.net: hannu set sender to hannu@tm.ee + using -f +Subject: Re: More tablescanning fun +From: Hannu Krosing +To: jim@nasby.net +Cc: Tom Lane , pgsql-performance@postgresql.org +In-Reply-To: <20030424235924.B66185@flake.decibel.org> +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Organization: +Message-Id: <1051288086.1765.95.camel@fuji.krosing.net> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.4 +Date: 25 Apr 2003 19:28:06 +0300 +X-Spam-Status: No, hits=-32.9 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_XIMIAN,X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/210 +X-Sequence-Number: 1716 + +Jim C. Nasby kirjutas R, 25.04.2003 kell 07:59: +> > > Also, is there a TODO to impliment +> > > real clustered indexes? +> > +> > No. It's not apparent to me how you could do that without abandoning +> > MVCC, which we're not likely to do. +> +> Hmm... does MVCC mandate inserts go at the end? + +I have been pondering if keeping pages half-empty (or even 70% empty) +could solve both clustering problems and longish updates for much data. + +If we could place the copy in the same page than original, most big +updates would be possible by one sweep of disk heads and also clustering +order would be easier to keep if pages were kept intentionally half +empty. + +So "VACUUM FULL 65% EMPTY;" could make sense ? + + +------------- +Hannu + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 12:56:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 88270475E77 + for ; + Fri, 25 Apr 2003 12:56:08 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 70615474E42 + for ; + Fri, 25 Apr 2003 12:56:07 -0400 (EDT) +Received: (qmail 13733 invoked by uid 1001); 25 Apr 2003 16:56:13 -0000 +Date: Fri, 25 Apr 2003 11:56:13 -0500 +From: "Jim C. Nasby" +To: Hannu Krosing +Cc: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +Message-ID: <20030425115613.E66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> + <1051288086.1765.95.camel@fuji.krosing.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <1051288086.1765.95.camel@fuji.krosing.net>; + from hannu@tm.ee on Fri, Apr 25, 2003 at 07:28:06PM +0300 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/211 +X-Sequence-Number: 1717 + +On Fri, Apr 25, 2003 at 07:28:06PM +0300, Hannu Krosing wrote: +> I have been pondering if keeping pages half-empty (or even 70% empty) +> could solve both clustering problems and longish updates for much data. +> +> If we could place the copy in the same page than original, most big +> updates would be possible by one sweep of disk heads and also clustering +> order would be easier to keep if pages were kept intentionally half +> empty. +> +> So "VACUUM FULL 65% EMPTY;" could make sense ? + +That's actually a recommended practice, at least for sybase when you're +using a clustered index, depending on what you're using it for. If you +cluster a table in such a way that inserts will happen across the entire +table, you'll actually end up with a fillratio (amount of data v. empty +space on a page) of 75% over time, because of page splits. When sybase +goes to insert, if it can't find room on the page it needs to insert +into (keep in mind this is a clustered table, so a given row *must* go +into a given position), it will split that single page into two pages, +each of which will then have a fillratio of 50%. Of course they'll +eventually approach 100%, so the average fill ratio across all pages for +the table would be 75%. + +I'm not familiar enough with pgsql's guts to know how big an impact +updates across pages are, or if they even happen often at all. If you're +not maintaining a clustered table, couldn't all updates just occur +in-place? Or are you thinking of the case where you have a lot of +variable-length stuff? +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-hackers-owner@postgresql.org Fri Apr 25 15:53:27 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4033F47630C + for ; + Fri, 25 Apr 2003 15:53:25 -0400 (EDT) +Received: from europa.janwieck.net (h00045a2e4e7c.ne.client2.attbi.com + [24.131.181.55]) + by postgresql.org (Postfix) with ESMTP id 729FC4763D8 + for ; + Fri, 25 Apr 2003 15:53:19 -0400 (EDT) +Received: from Yahoo.com (wieck@dhcpclnt00.janwieck.net [192.168.192.100]) + (authenticated) + by europa.janwieck.net (8.11.6/8.11.6) with ESMTP id h3PJqba24259; + Fri, 25 Apr 2003 15:52:38 -0400 +Message-ID: <3EA991F0.A201AC38@Yahoo.com> +Date: Fri, 25 Apr 2003 15:52:16 -0400 +From: Jan Wieck +Organization: Home +X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U) +X-Accept-Language: en,ru +MIME-Version: 1.0 +To: Stephan Szabo +Cc: Tom Lane , Kevin Brown , + pgsql-hackers@postgresql.org +Subject: Re: [PERFORM] Foreign key performance +References: <20030418073753.B1912-100000@megazone23.bigpanda.com> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-29.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/905 +X-Sequence-Number: 38395 + +Stephan Szabo wrote: +> +> [Not sure this really is relevant for -performance at this point] +> +> On Thu, 17 Apr 2003, Stephan Szabo wrote: +> +> > On Fri, 18 Apr 2003, Tom Lane wrote: +> > +> > > Stephan Szabo writes: +> > > > It appears (from some not terribly scientific experiments - see below) +> > > > that it's likely to be related to managing the deferred trigger queue +> > > > given that in my case at least running the constraints non-deferred was +> > > > negligible in comparison. +> > > +> > > At one time the deferred-trigger queue had an O(N^2) behavioral problem +> > > for large N = number of pending trigger events. But I thought we'd +> > > fixed that. What's the test case exactly? Can you get a profile with +> > > gprof? +> > +> > I'm going to tomorrow hopefully - but it looks to me that we fixed one, but +> +> Argh. I'm getting that state where gprof returns all 0s for times. I'm +> pretty sure this has come up before along with how to get it to work, but +> I couldn't find it in the archives. Someday I'll learn how to use gprof. :( + +You have to save and restore the timers around the fork() under Linux. + + +Jan + +-- +#======================================================================# +# It's easier to get forgiveness for being wrong than for being right. # +# Let's break this rule - forgive me. # +#================================================== JanWieck@Yahoo.com # + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 16:10:52 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 28063476375 + for ; + Fri, 25 Apr 2003 16:10:51 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 2F597476350 + for ; + Fri, 25 Apr 2003 16:10:50 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3PKAlU6029561; + Fri, 25 Apr 2003 16:10:49 -0400 (EDT) +To: Hannu Krosing +Cc: jim@nasby.net, pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +In-reply-to: <1051288086.1765.95.camel@fuji.krosing.net> +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> + <1051288086.1765.95.camel@fuji.krosing.net> +Comments: In-reply-to Hannu Krosing + message dated "25 Apr 2003 19:28:06 +0300" +Date: Fri, 25 Apr 2003 16:10:47 -0400 +Message-ID: <29560.1051301447@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/212 +X-Sequence-Number: 1718 + +Hannu Krosing writes: +> I have been pondering if keeping pages half-empty (or even 70% empty) +> could solve both clustering problems and longish updates for much data. + +You could achieve that pretty easily if you simply don't ever VACUUM +FULL ;-) + +UPDATE has always (AFAIR) attempted to place the new version on the same +page as the old, moving it elsewhere only if it doesn't fit. So that +part of the logic is already there. + +> So "VACUUM FULL 65% EMPTY;" could make sense ? + +Not so much that, as a parameter to CLUSTER telling it to fill pages +only x% full. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 18:33:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 708B6475C3D + for ; + Fri, 25 Apr 2003 18:33:12 -0400 (EDT) +Received: from hotmail.com (f42.law12.hotmail.com [64.4.19.42]) + by postgresql.org (Postfix) with ESMTP id B58E4474E42 + for ; + Fri, 25 Apr 2003 18:33:11 -0400 (EDT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Fri, 25 Apr 2003 15:33:14 -0700 +Received: from 200.67.81.177 by lw12fd.law12.hotmail.msn.com with HTTP; + Fri, 25 Apr 2003 22:33:13 GMT +X-Originating-IP: [200.67.81.177] +X-Originating-Email: [cecilia_ag@hotmail.com] +From: "Cecilia Alvarez" +To: pgsql-performance@postgresql.org +Subject: Indexes with different datatypes +Date: Fri, 25 Apr 2003 17:33:13 -0500 +Mime-Version: 1.0 +Content-Type: text/html; charset=iso-8859-1 +Message-ID: +X-OriginalArrivalTime: 25 Apr 2003 22:33:14.0019 (UTC) + FILETIME=[A8AAD730:01C30B7A] +X-Spam-Status: No, hits=-0.5 required=5.0 + tests=BAYES_30,HTML_60_70,HTML_FONT_COLOR_BLUE, + HTML_FONT_COLOR_GREEN,HTML_FONT_COLOR_RED version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/213 +X-Sequence-Number: 1719 + +

Hi,

+

I�ve already created an concatenated index in Postgres V3.0 with different datatypes:

+

CREATE INDEX mov_i4 ON movimiento USING btree (id_company, id_status, id_docum, id_origen_mov);

+

id_company int2

+

id_status char(1)

+

id_docum numeric(15,0)

+

id_origen_mov int4

+

and after several tests the query doesn�t use the index because it seems that id_company must be a char.

+

If a use the value for the id_company eg.   select * from movimiento where id_company = 120

+

                                                          and id_status = 'X' and id_docto = 10000056789 and mount = 12345.56

+

---- it doesn�t use the index                                                                               

+

If a use the value for the id_company eg.   select * from movimiento where id_company = '120' and

+

                                                     and id_status = 'X' and id_docto = 10000056789 and mount = 12345.56

+

---- it  uses the index

+

 

+

The problem is that I can�t change the datatypes in the hole application and the table has 240,000 rows and we need to use concatenated indexes, because we access the table in different ways, the table has another five concatenated indexes.

+

Could you suggest something to resolve this?

+

Thank you very much.

+

Regards,

+

Cecilia

+

 

+
 

�nete al mayor servicio mundial de correo electr�nico: Haz clic aqu� + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 18:36:47 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0C548475C3D + for ; + Fri, 25 Apr 2003 18:36:47 -0400 (EDT) +Received: from hotmail.com (f28.law12.hotmail.com [64.4.19.28]) + by postgresql.org (Postfix) with ESMTP id 4526C474E42 + for ; + Fri, 25 Apr 2003 18:36:46 -0400 (EDT) +Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; + Fri, 25 Apr 2003 15:36:48 -0700 +Received: from 200.67.81.177 by lw12fd.law12.hotmail.msn.com with HTTP; + Fri, 25 Apr 2003 22:36:48 GMT +X-Originating-IP: [200.67.81.177] +X-Originating-Email: [cecilia_ag@hotmail.com] +From: "Cecilia Alvarez" +To: pgsql-performance@postgresql.org +Subject: Indexes with different datatypes:Correction +Date: Fri, 25 Apr 2003 17:36:48 -0500 +Mime-Version: 1.0 +Content-Type: text/html; charset=iso-8859-1 +Message-ID: +X-OriginalArrivalTime: 25 Apr 2003 22:36:48.0719 (UTC) + FILETIME=[28A375F0:01C30B7B] +X-Spam-Status: No, hits=-0.5 required=5.0 + tests=BAYES_30,HTML_60_70,HTML_FONT_COLOR_BLUE, + HTML_FONT_COLOR_GREEN,HTML_FONT_COLOR_RED version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/214 +X-Sequence-Number: 1720 + +
+



+
+

Sorry, this is the good one:

+

I�ve already created an concatenated index in Postgres V3.0 with different datatypes:

+

CREATE INDEX mov_i4 ON movimiento USING btree (id_company, id_status, id_docum, id_origen_mov);

+
+

id_company int2

+
+

id_status char(1)

+
+

id_docum numeric(15,0)

+
+

id_origen_mov int4

+
+

and after several tests the query doesn�t use the index because it seems that id_company must be a char.

+
+

If a use the value for the id_company eg.   select * from movimiento where id_company = 120

+
+

                                                          and id_status = 'X' and id_docum = 10000056789 and id_origen_mov = 12345

+
+

---- it doesn�t use the index                                                                               

+
+

If a use the value for the id_company eg.   select * from movimiento where id_company = '120' and

+
+

                                                     and id_status = 'X' and id_docum = 10000056789 and id_origen_mov = 12345

+
+

---- it  uses the index

+
+

 

+
+

The problem is that I can�t change the datatypes in the hole application and the table has 240,000 rows and we need to use concatenated indexes, because we access the table in different ways, the table has another five concatenated indexes.

+
+

Could you suggest something to resolve this?

+
+

Thank you very much.

+
+

Regards,

+
+

Cecilia

+
+

 

+
+
 
+

MSN. M�s �til Cada D�a Haz clic aqu� smart spam protection and 2 months FREE* + + +From pgsql-performance-owner@postgresql.org Fri Apr 25 18:49:42 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3E35F475C3D + for ; + Fri, 25 Apr 2003 18:49:39 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 11B18474E42 + for ; + Fri, 25 Apr 2003 18:49:37 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3PMnI3W019790; + Fri, 25 Apr 2003 16:49:18 -0600 (MDT) +Date: Fri, 25 Apr 2003 16:40:54 -0600 (MDT) +From: "scott.marlowe" +To: Cecilia Alvarez +Cc: +Subject: Re: Indexes with different datatypes:Correction +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=ISO-8859-1 +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/215 +X-Sequence-Number: 1721 + +On Fri, 25 Apr 2003, Cecilia Alvarez wrote: + +>=20 +>=20 +>=20 +> Sorry, this is the good one: +>=20 +> I=B4ve already created an concatenated index in Postgres V3.0 with differ= +ent datatypes: +>=20 +> CREATE INDEX mov_i4 ON movimiento USING btree (id_company, id_status, id_= +docum, +> id_origen_mov); +>=20 +> id_company int2 +>=20 +> id_status char(1) +>=20 +> id_docum numeric(15,0) +>=20 +> id_origen_mov int4 +>=20 +> and after several tests the query doesn=B4t use the index because it seem= +s=A0that id_company must +> be a char. +>=20 +> If a use=A0the value for the id_company eg.=A0=A0 select * from movimient= +o where id_company =3D 120 +>=20 +> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0=A0=A0and id_status =3D 'X' and id_docum =3D +> 10000056789 and=A0id_origen_mov =3D 12345 +>=20 +> ---- it doesn=B4t use the +> index=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0 +>=20 +> If a use=A0the value for the id_company eg.=A0=A0 select * from movimient= +o where id_company =3D '120' +> and +>=20 +> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= +=A0=A0=A0=A0and id_status =3D 'X' and id_docum =3D +> 10000056789 and=A0id_origen_mov =3D 12345 +>=20 +> ---- it=A0 uses the index +>=20 +> =A0 +>=20 +> The problem is that I can=B4t change the datatypes in the hole applicatio= +n and the table has +> 240,000 rows and=A0we need to use concatenated indexes, because we access= + the table in +> different ways, the table has another five concatenated indexes. +>=20 +> Could you suggest something to resolve this? + +Hi Cecilia. It looks like the problem is that Postgresql assumes that a=20 +non-quoted number is generally an int4, and since the id_company is int2,= +=20 +it isn't automatically converted. You can either change your app to force= +=20 +coercion (which the '' quotes are doing) or like: + +where id_company =3D 120::int2=20 +OR +where id =3D cast(120 as int2) + +OR you can recreate your table with id_company being int4. If you NEED to= +=20 +restrict it to int2 range, then you can use a constraint to make it act=20 +like an int2 without actually being one. + + +From pgsql-performance-owner@postgresql.org Sat Apr 26 11:15:39 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3CFEF475A80 + for ; + Sat, 26 Apr 2003 11:15:38 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id D7D67474E4F + for ; + Sat, 26 Apr 2003 11:15:33 -0400 (EDT) +Received: (qmail 71747 invoked by uid 1001); 26 Apr 2003 15:15:37 -0000 +Date: Sat, 26 Apr 2003 10:15:37 -0500 +From: "Jim C. Nasby" +To: pgsql-performance@postgresql.org +Subject: Automatic analyze on select into +Message-ID: <20030426101537.F66185@flake.decibel.org> +Reply-To: jim@nasby.net +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-13.5 required=5.0 + tests=BAYES_01,SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/216 +X-Sequence-Number: 1722 + +BEGIN; + SET LOCAL enable_seqscan = off; + SELECT id, team_id, sum(work_units) AS work_units + INTO TEMP email_contrib_summary + FROM email_contrib + WHERE project_id = :ProjectID + GROUP by id, team_id + ; +COMMIT; + +inserts 29000 rows... + +UPDATE email_contrib_summary + SET id = sp.retire_to + FROM stats_participant sp + WHERE sp.id = email_contrib_summary.id + AND sp.retire_to >= 0 + AND (sp.retire_date >= (SELECT ps.last_date FROM project_statsrun ps WHERE ps.project_id = :ProjectID) + OR sp.retire_date IS NULL) +; + Nested Loop (cost=0.00..5475.20 rows=982 width=54) (actual time=25.54..2173363.11 rows=29181 loops=1) + InitPlan + -> Seq Scan on project_statsrun ps (cost=0.00..1.06 rows=1 width=4) (actual time=0.06..0.07 rows=1 loops=1) + Filter: (project_id = 8) + -> Seq Scan on email_contrib_summary (cost=0.00..20.00 rows=1000 width=46) (actual time=25.11..1263.26 rows=29753 loops=1) + -> Index Scan using stats_participant__participantretire_id on stats_participant sp (cost=0.00..5.44 rows=1 width=8) (actual time=2.16..72.93 rows=1 loops=29753) + Index Cond: ((sp.retire_to >= 0) AND (sp.id = "outer".id)) + Filter: ((retire_date >= $0) OR (retire_date IS NULL)) + Total runtime: 2174315.61 msec + +GAH! 45 minutes to update 29k rows! BUT, if I do + + Hash Join (cost=41104.03..42410.14 rows=29166 width=38) (actual time=8391.81..10925.07 rows=29181 loops=1) + Hash Cond: ("outer".id = "inner".id) + InitPlan + -> Seq Scan on project_statsrun ps (cost=0.00..1.06 rows=1 width=4) (actual time=0.05..0.06 rows=1 loops=1) + Filter: (project_id = 8) + -> Seq Scan on email_contrib_summary (cost=0.00..496.01 rows=29701 width=30) (actual time=0.20..387.95 rows=29753 loops=1) + -> Hash (cost=13939.69..13939.69 rows=394217 width=8) (actual time=8390.72..8390.72 rows=0 loops=1) + -> Seq Scan on stats_participant sp (cost=0.00..13939.69 rows=394217 width=8) (actual time=0.22..5325.38 rows=389115 loops=1) + Filter: ((retire_to >= 0) AND ((retire_date >= $0) OR (retire_date IS NULL))) + Total runtime: 11584.09 msec + + +Ahhh... soothing relief... + +So, question is, would it make sense to automatically do an analyze +after/during a SELECT INTO? Would it be very expensive to analyze the +data as it's being inserted? I think it's pretty well understood that +you want to vacuum/vacuum analyze the entire database regularly, but +that obviously wouldn't help temporary tables... maybe it makes the most +sense to automatically analyze temporary tables only. For that matter, +since temp tables only have one operation performed on them at a time, +maybe it makes sense to keep stats for them up-to-date as part of every +operation? +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Sat Apr 26 12:18:58 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 50895474E4F + for ; + Sat, 26 Apr 2003 12:18:56 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 88C63474E42 + for ; + Sat, 26 Apr 2003 12:18:51 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3QGIsU6008336; + Sat, 26 Apr 2003 12:18:54 -0400 (EDT) +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: Automatic analyze on select into +In-reply-to: <20030426101537.F66185@flake.decibel.org> +References: <20030426101537.F66185@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Sat, 26 Apr 2003 10:15:37 -0500" +Date: Sat, 26 Apr 2003 12:18:54 -0400 +Message-ID: <8335.1051373934@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/217 +X-Sequence-Number: 1723 + +"Jim C. Nasby" writes: +> So, question is, would it make sense to automatically do an analyze +> after/during a SELECT INTO? + +I don't think so. Very often, temp tables are small and only used for +one or two operations anyway --- so the cost of an ANALYZE wouldn't be +repaid. If ANALYZE would be useful, the user can issue one. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sat Apr 26 14:16:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 74F11475D0F + for ; + Sat, 26 Apr 2003 14:16:26 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 1EC5C475A80 + for ; + Sat, 26 Apr 2003 14:16:25 -0400 (EDT) +Received: (qmail 78505 invoked by uid 1001); 26 Apr 2003 18:16:25 -0000 +Date: Sat, 26 Apr 2003 13:16:25 -0500 +From: "Jim C. Nasby" +To: Tom Lane +Cc: pgsql-performance@postgresql.org +Subject: Re: Automatic analyze on select into +Message-ID: <20030426131624.G66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030426101537.F66185@flake.decibel.org> + <8335.1051373934@sss.pgh.pa.us> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <8335.1051373934@sss.pgh.pa.us>; + from tgl@sss.pgh.pa.us on Sat, Apr 26, 2003 at 12:18:54PM -0400 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/218 +X-Sequence-Number: 1724 + +On Sat, Apr 26, 2003 at 12:18:54PM -0400, Tom Lane wrote: +> "Jim C. Nasby" writes: +> > So, question is, would it make sense to automatically do an analyze +> > after/during a SELECT INTO? +> +> I don't think so. Very often, temp tables are small and only used for +> one or two operations anyway --- so the cost of an ANALYZE wouldn't be +> repaid. If ANALYZE would be useful, the user can issue one. + +Ok, I'll add notes to appropriate pages in the documentation. BTW, do +the notes entered into the interactive docs get rolled into the formal +documentation at any point? +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Sat Apr 26 14:40:13 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 38F1A474E4F + for ; + Sat, 26 Apr 2003 14:40:12 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 72E2F474E42 + for ; + Sat, 26 Apr 2003 14:40:11 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3QIe8U6014275; + Sat, 26 Apr 2003 14:40:08 -0400 (EDT) +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: Automatic analyze on select into +In-reply-to: <20030426131624.G66185@flake.decibel.org> +References: <20030426101537.F66185@flake.decibel.org> + <8335.1051373934@sss.pgh.pa.us> + <20030426131624.G66185@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Sat, 26 Apr 2003 13:16:25 -0500" +Date: Sat, 26 Apr 2003 14:40:08 -0400 +Message-ID: <14274.1051382408@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/219 +X-Sequence-Number: 1725 + +"Jim C. Nasby" writes: +> Ok, I'll add notes to appropriate pages in the documentation. BTW, do +> the notes entered into the interactive docs get rolled into the formal +> documentation at any point? + +Usually, towards the end of a release cycle, someone will run through +them looking for stuff worth incorporating into the next generation. +It's pretty informal though. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Sun Apr 27 02:50:58 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B394F475AE5 + for ; + Sun, 27 Apr 2003 02:50:56 -0400 (EDT) +Received: from fuji.krosing.net (unknown [194.204.44.118]) + by postgresql.org (Postfix) with ESMTP id F25E2474E42 + for ; + Sun, 27 Apr 2003 02:50:54 -0400 (EDT) +Received: from fuji.krosing.net (lo [127.0.0.1]) + by fuji.krosing.net (8.12.8/8.12.8) with ESMTP id h3R6oqoJ001925; + Sun, 27 Apr 2003 09:50:52 +0300 +Received: (from hannu@localhost) + by fuji.krosing.net (8.12.8/8.12.8/Submit) id h3R6opFt001922; + Sun, 27 Apr 2003 09:50:51 +0300 +X-Authentication-Warning: fuji.krosing.net: hannu set sender to hannu@tm.ee + using -f +Subject: Re: More tablescanning fun +From: Hannu Krosing +To: jim@nasby.net +Cc: Tom Lane , pgsql-performance@postgresql.org +In-Reply-To: <20030425115613.E66185@flake.decibel.org> +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> + <1051288086.1765.95.camel@fuji.krosing.net> + <20030425115613.E66185@flake.decibel.org> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +Organization: +Message-Id: <1051426250.1860.1.camel@fuji.krosing.net> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.4 +Date: 27 Apr 2003 09:50:51 +0300 +X-Spam-Status: No, hits=-32.9 required=5.0 + tests=BAYES_10,IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_XIMIAN,X_AUTH_WARNING + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/220 +X-Sequence-Number: 1726 + +Jim C. Nasby kirjutas R, 25.04.2003 kell 19:56: +> I'm not familiar enough with pgsql's guts to know how big an impact +> updates across pages are, or if they even happen often at all. If you're +> not maintaining a clustered table, couldn't all updates just occur +> in-place? + +In postgres _no_ updates happen in-place. The MVCC concurrency works by +always inserting a new tuple on update . + +----------- +Hannu + + +From pgsql-performance-owner@postgresql.org Sun Apr 27 22:30:24 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 55C264758C9 + for ; + Sun, 27 Apr 2003 22:30:23 -0400 (EDT) +Received: from cable.kevindegraaf.net (12-245-24-71.client.attbi.com + [12.245.24.71]) by postgresql.org (Postfix) with SMTP id 9B638474E42 + for ; + Sun, 27 Apr 2003 22:30:20 -0400 (EDT) +Received: (qmail 1371 invoked from network); 28 Apr 2003 02:30:31 -0000 +Received: from unknown (HELO ungoliant) (192.168.1.3) + by cable.kevindegraaf.net with SMTP; 28 Apr 2003 02:30:31 -0000 +From: Jeremy Andrus +Reply-To: jeremy@jeremya.com +Organization: http://www.jeremya.com/ +To: pgsql-performance@postgresql.org +Subject: pgsql BLOB issues +Date: Sun, 27 Apr 2003 22:30:23 -0400 +User-Agent: KMail/1.5 +X-Rokken: Dokken +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304272230.23583@jeremy-rokks> +X-Spam-Status: No, hits=-5.8 required=5.0 tests=BAYES_10,USER_AGENT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/221 +X-Sequence-Number: 1727 + +Hello, + + I have a database that contains a large amount of Large Objects +(>500MB). I am using this database to store images for an e-commerce +website, so I have a simple accessor script written in perl to dump out +a blob based on a virtual 'path' stored in a table (and associated with +the large object's OID). This system seemed to work wonderfully until I +put more than ~500MB of binary data into the database. + + Now, every time I run the accessor script (via the web OR the command +line), the postmaster process gobbles up my CPU resources (usually >30% +for a single process - and it's a 1GHz processor with 1GB of RAM!), and +the script takes a very long time to completely dump out the data. + + I have the same issue with an import script that reads files from the +hard drive and puts them into Large Objects in the database. It takes a +very long time to import whereas before, it would run extremely fast. + + Are there any known issues in PostgreSQL involving databases with a +lot of binary data? I am using PostgreSQL v7.2.3 on a linux system. + +Thanks, + + -Jeremy + +-- +------------------------ +Jeremy C. Andrus +http://www.jeremya.com/ +------------------------ + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 01:00:22 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8DF0D474E42 + for ; + Mon, 28 Apr 2003 01:00:19 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 40D7C475956 + for ; + Mon, 28 Apr 2003 01:00:08 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3S501U6011755; + Mon, 28 Apr 2003 01:00:01 -0400 (EDT) +To: jeremy@jeremya.com +Cc: pgsql-performance@postgresql.org +Subject: Re: pgsql BLOB issues +In-reply-to: <200304272230.23583@jeremy-rokks> +References: <200304272230.23583@jeremy-rokks> +Comments: In-reply-to Jeremy Andrus + message dated "Sun, 27 Apr 2003 22:30:23 -0400" +Date: Mon, 28 Apr 2003 01:00:01 -0400 +Message-ID: <11754.1051506001@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.5 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/222 +X-Sequence-Number: 1728 + +Jeremy Andrus writes: +> I have a database that contains a large amount of Large Objects +> (>500MB). I am using this database to store images for an e-commerce +> website, so I have a simple accessor script written in perl to dump out +> a blob based on a virtual 'path' stored in a table (and associated with +> the large object's OID). This system seemed to work wonderfully until I +> put more than ~500MB of binary data into the database. + +Are you talking about 500MB in one BLOB, or 500MB total? + +If the former, I can well imagine swap thrashing being a problem when +you try to access such a large blob. + +If the latter, I can't think of any reason for total blob storage to +cause any big performance issue. Perhaps you just haven't vacuumed +pg_largeobject in a long time? + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 01:33:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A8E774758C9 + for ; + Mon, 28 Apr 2003 01:33:44 -0400 (EDT) +Received: from cable.kevindegraaf.net (12-245-24-71.client.attbi.com + [12.245.24.71]) by postgresql.org (Postfix) with SMTP id CAD8B474E42 + for ; + Mon, 28 Apr 2003 01:33:39 -0400 (EDT) +Received: (qmail 1395 invoked from network); 28 Apr 2003 05:33:46 -0000 +Received: from unknown (HELO ungoliant) (192.168.1.3) + by cable.kevindegraaf.net with SMTP; 28 Apr 2003 05:33:46 -0000 +From: Jeremy Andrus +Reply-To: jeremy@jeremya.com +Organization: http://www.jeremya.com/ +To: Tom Lane +Subject: Re: pgsql BLOB issues +Date: Mon, 28 Apr 2003 01:33:38 -0400 +User-Agent: KMail/1.5 +References: <200304272230.23583@jeremy-rokks> <11754.1051506001@sss.pgh.pa.us> +In-Reply-To: <11754.1051506001@sss.pgh.pa.us> +Cc: pgsql-performance@postgresql.org +X-Rokken: Dokken +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304280133.38335@jeremy-rokks> +X-Spam-Status: No, hits=-29.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/223 +X-Sequence-Number: 1729 + +On Monday 28 April 2003 01:00 am, Tom Lane wrote: +> Are you talking about 500MB in one BLOB, or 500MB total? + + I meant 500MB _total_. There are over 5000 separate BLOBs. + + I'll ask my friendly sys-admin to vacuum pg_largeobject, and I'll let +you know what happens :-) In general though, how much performance is +really gained through regular vacuuming? + +Thanks for your help, + + -Jeremy + +-- +------------------------ +Jeremy C. Andrus +http://www.jeremya.com/ +------------------------ + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 04:20:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 70CF54758C9 + for ; + Mon, 28 Apr 2003 04:20:05 -0400 (EDT) +Received: from houston.familyhealth.com.au (unknown [203.59.48.253]) + by postgresql.org (Postfix) with ESMTP id F3DA8475EEE + for ; + Mon, 28 Apr 2003 04:19:56 -0400 (EDT) +Received: (from root@localhost) + by houston.familyhealth.com.au (8.11.6p2/8.11.6) id h3S8JuF56548 + for pgsql-performance@postgresql.org; + Mon, 28 Apr 2003 16:19:56 +0800 (WST) + (envelope-from chriskl@familyhealth.com.au) +Received: from mariner (mariner.internal [192.168.0.101]) + by houston.familyhealth.com.au (8.11.6p2/8.9.3) with SMTP id + h3S8JnJ56413; Mon, 28 Apr 2003 16:19:49 +0800 (WST) +Message-ID: <005e01c30d5e$f0209560$6500a8c0@fhp.internal> +From: "Christopher Kings-Lynne" +To: , "Tom Lane" +Cc: +References: <200304272230.23583@jeremy-rokks> <11754.1051506001@sss.pgh.pa.us> + <200304280133.38335@jeremy-rokks> +Subject: Re: pgsql BLOB issues +Date: Mon, 28 Apr 2003 16:19:50 +0800 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1158 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 +X-scanner: scanned by Inflex 0.1.5c - (http://www.inflex.co.za/) +X-Spam-Status: No, hits=-12.8 required=5.0 + tests=BAYES_20,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/224 +X-Sequence-Number: 1730 + +> I'll ask my friendly sys-admin to vacuum pg_largeobject, and I'll let +> you know what happens :-) In general though, how much performance is +> really gained through regular vacuuming? + +Significant. It's essential to vacuum regularly. + +Chris + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 06:39:16 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 583F44758C9 + for ; + Mon, 28 Apr 2003 06:39:14 -0400 (EDT) +Received: from dos.sipec.es (unknown [62.36.228.122]) + by postgresql.org (Postfix) with ESMTP id 24866474E42 + for ; + Mon, 28 Apr 2003 06:39:08 -0400 (EDT) +Received: from sistemests2 ([10.1.1.128]) by dos.sipec.es with Microsoft + SMTPSVC(5.0.2195.5329); Mon, 28 Apr 2003 12:26:04 +0200 +From: +To: +Subject: Diferent execution plan for similar query +Date: Mon, 28 Apr 2003 12:26:03 +0200 +Message-ID: <003401c30d70$92c07310$8001010a@sipec.es> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2910.0) +X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6700 +Importance: Normal +X-OriginalArrivalTime: 28 Apr 2003 10:26:04.0765 (UTC) + FILETIME=[92D840D0:01C30D70] +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-0.8 required=5.0 + tests=BAYES_20,NO_DNS_FOR_FROM,NO_REAL_NAME version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/225 +X-Sequence-Number: 1731 + +Somebody could explain me why this query... + + SELECT * + FROM articulos,eans + WHERE articulos.id_iinterno=3Deans.id_iinterno + AND eans.id_iean=3D345 + +is slower than this one? (the difference is the quotes around the +number....) + + SELECT * + FROM articulos,eans + WHERE articulos.id_iinterno=3Deans.id_iinterno + AND eans.id_iean=3D'345' + +I really now why, but I don't undestand the reason. The execution plan for +the first query uses +Sequential scans, and the second one uses the index, as you can see here: + +Execution plan for the first query: + + Nested Loop (cost=3D0.00..8026.85 rows=3D1 width=3D133) + -> Seq Scan on eans (cost=3D0.00..8023.74 rows=3D1 width=3D16) + -> Index Scan using articulos_pk on articulos (cost=3D0.00..3.10 rows= +=3D1 +width=3D117) + +And this is the second: + + Nested Loop (cost=3D0.00..9.12 rows=3D1 width=3D133) + -> Index Scan using eans_pk on eans (cost=3D0.00..6.01 rows=3D1 width= +=3D16) + -> Index Scan using articulos_pk on articulos (cost=3D0.00..3.10 rows= +=3D1 +width=3D117) + +The field id_iean is an 8 bytes integer. Also the same for the field +id_iinterno in both tables. + +The definition of the 2 tables is this: + + CREATE TABLE "eans" ( + "id_iean" int8 NOT NULL, + "id_iinterno" int8, + CONSTRAINT "eans_pk" PRIMARY KEY ("id_iean") + ) WITH OIDS; + + CREATE TABLE "articulos" ( + "id_iinterno" int8 NOT NULL, + "vsdesc_calypso" varchar(20), + "id_iseccion" int4, + "iprecio" int4, + "ifamilia" int8, + "icod_proveedor" int4, + "vsmarca" varchar(10), + "vsdesc_larga" varchar(22), + "bnulo" bool, + "bcontrol_devolucion" bool, + "itipo_pedido" int2, + "isurtido" int2, + "ifuera_lineal" int2, + "idias_caducidad" int2, + "iuni_x_caja" int2, + "suni_medida" varchar(2), + "suni_pedido" varchar(3), + CONSTRAINT "articulos_pk" PRIMARY KEY ("id_iinterno") + ) WITH OIDS; + + +What I don't understand is why the quotes in the number result in a diferent +query execution. Somebody could help me? + +Thank you for your help. + +Jordi Gim=E9nez . +Analista Software Departamento Calypso. +Soluciones Inform=E1ticas Para El Comercio, S.L. +jgimenez(arroba)sipec.es + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 06:41:55 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3CFF74758C9 + for ; + Mon, 28 Apr 2003 06:41:55 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 595F3474E42 + for ; + Mon, 28 Apr 2003 06:41:53 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h3SAfsU09457 + for ; Mon, 28 Apr 2003 16:11:54 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h3SAfsx09452 + for ; Mon, 28 Apr 2003 16:11:54 +0530 +From: Shridhar Daithankar +To: +Subject: Re: Diferent execution plan for similar query +Date: Mon, 28 Apr 2003 16:11:33 +0530 +User-Agent: KMail/1.5.1 +References: <003401c30d70$92c07310$8001010a@sipec.es> +In-Reply-To: <003401c30d70$92c07310$8001010a@sipec.es> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304281611.33669.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-38.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/226 +X-Sequence-Number: 1732 + +On Monday 28 April 2003 15:56, jgimenez@sipec_quitaesto_.es wrote: +> Somebody could explain me why this query... +> +> SELECT * +> FROM articulos,eans +> WHERE articulos.id_iinterno=eans.id_iinterno +> AND eans.id_iean=345 +> +> is slower than this one? (the difference is the quotes around the +> number....) +> +> SELECT * +> FROM articulos,eans +> WHERE articulos.id_iinterno=eans.id_iinterno +> AND eans.id_iean='345' + +In second case, postgresql typecasted it correctly. Even +eans.id_iean=345::int8 would have worked the same way. By default postgresql +treats a number as int4 while comparing and integer and float8 for a real +numbe. I discovered that yesterday. + +Until the planner/parser gets smarter, this is going to be an FAQ.. + + Shridhar + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 06:59:39 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 977B8474E42 + for ; + Mon, 28 Apr 2003 06:59:37 -0400 (EDT) +Received: from mail2.fbab.net (spectre.fbab.net [195.54.134.139]) + by postgresql.org (Postfix) with SMTP id 1BF33474E42 + for ; + Mon, 28 Apr 2003 06:59:06 -0400 (EDT) +Received: (qmail 5195 invoked by uid 136); 28 Apr 2003 10:59:07 -0000 +Received: from mag@fbab.net by mail2.fbab.net + by uid 133 with qmail-scanner-1.10 (F-PROT: 3.11. Clear:0. Processed in + 0.267225 secs); 28 Apr 2003 10:59:07 -0000 +X-Qmail-Scanner-Mail-From: mag@fbab.net via mail2.fbab.net +X-Qmail-Scanner: 1.10 (Clear:0. Processed in 0.267225 secs) +Received: from unknown (HELO mail2.fbab.net:444) (195.54.134.228) + by mail2.fbab.net with SMTP; 28 Apr 2003 10:59:07 -0000 +Received: from 129.178.88.66 (SquirrelMail authenticated user magimap1) + by mail2.fbab.net with HTTP; Mon, 28 Apr 2003 12:59:07 +0200 (CEST) +Message-ID: <59937.129.178.88.66.1051527547.squirrel@mail2.fbab.net> +In-Reply-To: <200304281611.33669.shridhar_daithankar@nospam.persistent.co.in> +References: <003401c30d70$92c07310$8001010a@sipec.es> + <200304281611.33669.shridhar_daithankar@nospam.persistent.co.in> +Date: Mon, 28 Apr 2003 12:59:07 +0200 (CEST) +Subject: Re: Diferent execution plan for similar query +From: "Magnus Naeslund(w)" +To: "Shridhar Daithankar" +Cc: pgsql-performance@postgresql.org +Reply-To: mag@fbab.net +User-Agent: SquirrelMail/1.4.0 +MIME-Version: 1.0 +Content-Type: text/plain;charset=iso-8859-1 +X-Priority: 3 +Importance: Normal +X-Spam-Status: No, hits=-25.4 required=5.0 + tests=BAYES_01,IN_REP_TO,PRIORITY_NO_NAME,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/227 +X-Sequence-Number: 1733 + + +Shridhar Daithankar said: +> +> In second case, postgresql typecasted it correctly. Even +> eans.id_iean=345::int8 would have worked the same way. By default +> postgresql +> treats a number as int4 while comparing and integer and float8 for a real +> numbe. I discovered that yesterday. +> +> Until the planner/parser gets smarter, this is going to be an FAQ.. +> +> Shridhar + +Is this an nontrivial change? +Because if it's trivial it should be done, imho. +I've been bitten indirectly of this, and it's not too easy to find out +always. I think that this is one of the most unobvious performance hickups +there are with postgresql. + +Magnus + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 07:00:19 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2A6AB475E14 + for ; + Mon, 28 Apr 2003 07:00:15 -0400 (EDT) +Received: from mail2.fbab.net (spectre.fbab.net [195.54.134.139]) + by postgresql.org (Postfix) with SMTP id BF739475B47 + for ; + Mon, 28 Apr 2003 07:00:01 -0400 (EDT) +Received: (qmail 5275 invoked by uid 136); 28 Apr 2003 11:00:04 -0000 +Received: from mag@fbab.net by mail2.fbab.net + by uid 133 with qmail-scanner-1.10 (F-PROT: 3.11. Clear:0. Processed in + 0.265754 secs); 28 Apr 2003 11:00:04 -0000 +X-Qmail-Scanner-Mail-From: mag@fbab.net via mail2.fbab.net +X-Qmail-Scanner: 1.10 (Clear:0. Processed in 0.265754 secs) +Received: from unknown (HELO mail2.fbab.net:444) (195.54.134.228) + by mail2.fbab.net with SMTP; 28 Apr 2003 11:00:03 -0000 +Received: from 129.178.88.66 (SquirrelMail authenticated user magimap1) + by mail2.fbab.net with HTTP; Mon, 28 Apr 2003 13:00:03 +0200 (CEST) +Message-ID: <62257.129.178.88.66.1051527603.squirrel@mail2.fbab.net> +Date: Mon, 28 Apr 2003 13:00:03 +0200 (CEST) +Subject: Re: Diferent execution plan for similar query +From: "Magnus Naeslund(w)" +To: "Shridhar Daithankar" +Cc: pgsql-performance@postgresql.org +Reply-To: mag@fbab.net +User-Agent: SquirrelMail/1.4.0 +MIME-Version: 1.0 +Content-Type: text/plain;charset=iso-8859-1 +X-Priority: 3 +Importance: Normal +X-Spam-Status: No, hits=-9.2 required=5.0 + tests=BAYES_01,PRIORITY_NO_NAME,QUOTED_EMAIL_TEXT,USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/228 +X-Sequence-Number: 1734 + + +Shridhar Daithankar said: +> +> In second case, postgresql typecasted it correctly. Even +> eans.id_iean=345::int8 would have worked the same way. By default +> postgresql +> treats a number as int4 while comparing and integer and float8 for a real +> numbe. I discovered that yesterday. +> +> Until the planner/parser gets smarter, this is going to be an FAQ.. +> +> Shridhar + +Is this an nontrivial change? +Because if it's trivial it should be done, imho. +I've been bitten indirectly of this, and it's not too easy to find out +always. I think that this is one of the most unobvious performance hickups +there are with postgresql. + +Magnus + + +From pgsql-hackers-owner@postgresql.org Mon Apr 28 07:01:20 2003 +X-Original-To: pgsql-hackers@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 35265475E14 + for ; + Mon, 28 Apr 2003 07:01:16 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 1B960475B99 + for ; + Mon, 28 Apr 2003 07:01:14 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h3SB1Fm12275 + for ; Mon, 28 Apr 2003 16:31:15 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h3SB1Fx12265; + Mon, 28 Apr 2003 16:31:15 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Diferent execution plan for similar query +Date: Mon, 28 Apr 2003 16:30:55 +0530 +User-Agent: KMail/1.5.1 +References: <003401c30d70$92c07310$8001010a@sipec.es> + <200304281611.33669.shridhar_daithankar@nospam.persistent.co.in> + <59937.129.178.88.66.1051527547.squirrel@mail2.fbab.net> +In-Reply-To: <59937.129.178.88.66.1051527547.squirrel@mail2.fbab.net> +Cc: pgsql-hackers@postgresql.org +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304281630.55041.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-38.9 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/953 +X-Sequence-Number: 38443 + +On Monday 28 April 2003 16:29, Magnus Naeslund(w) wrote: +> Shridhar Daithankar said: +> > In second case, postgresql typecasted it correctly. Even +> > eans.id_iean=345::int8 would have worked the same way. By default +> > postgresql +> > treats a number as int4 while comparing and integer and float8 for a real +> > numbe. I discovered that yesterday. +> > +> > Until the planner/parser gets smarter, this is going to be an FAQ.. +> > +> > Shridhar +> +> Is this an nontrivial change? +> Because if it's trivial it should be done, imho. +> I've been bitten indirectly of this, and it's not too easy to find out +> always. I think that this is one of the most unobvious performance hickups +> there are with postgresql. + +I would say dig into hackers archives for the consensus(??) reached.. I don't +remember.. + + Shridhar + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 07:12:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4A0BC4758C9 + for ; + Mon, 28 Apr 2003 07:12:08 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id 51B1A474E42 + for ; + Mon, 28 Apr 2003 07:12:04 -0400 (EDT) +Received: from [10.1.2.130] (helo=dba2) + by mail.libertyrms.com with esmtp (Exim 3.22 #3 (Debian)) + id 19A6YJ-0003aJ-00 + for ; Mon, 28 Apr 2003 07:12:07 -0400 +Received: by dba2 (Postfix, from userid 1019) + id D8C42CEDF; Mon, 28 Apr 2003 07:12:06 -0400 (EDT) +Date: Mon, 28 Apr 2003 07:12:06 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: Diferent execution plan for similar query +Message-ID: <20030428111206.GA15801@libertyrms.info> +Mail-Followup-To: Andrew Sullivan , + pgsql-performance@postgresql.org +References: <62257.129.178.88.66.1051527603.squirrel@mail2.fbab.net> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <62257.129.178.88.66.1051527603.squirrel@mail2.fbab.net> +User-Agent: Mutt/1.5.3i +X-Spam-Status: No, hits=-34.8 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/230 +X-Sequence-Number: 1736 + +On Mon, Apr 28, 2003 at 01:00:03PM +0200, Magnus Naeslund(w) wrote: +> Is this an nontrivial change? +> Because if it's trivial it should be done, imho. + +It's not trivial. If it were, it would have been done already. + +See the TODO entries about this, and the many discussions about it on +-hackers, for why it's not trivial. + +A +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 14:21:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0D62547638F + for ; + Mon, 28 Apr 2003 14:21:47 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id AE642475956 + for ; + Mon, 28 Apr 2003 14:21:43 -0400 (EDT) +Received: (qmail 95382 invoked by uid 1001); 28 Apr 2003 18:21:43 -0000 +Date: Mon, 28 Apr 2003 13:21:43 -0500 +From: "Jim C. Nasby" +To: pgsql-performance@postgresql.org +Subject: How to get the optimizer to use an index with multiple fields +Message-ID: <20030428132143.J66185@flake.decibel.org> +Reply-To: jim@nasby.net +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-13.5 required=5.0 + tests=BAYES_01,SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/231 +X-Sequence-Number: 1737 + +select id into temp NewRetires from stats_participant where retire_to>=1 +AND retire_date = (SELECT last_date FROM Project_statsrun WHERE +project_id = :ProjectID); + +results in a table with 5 values... + +explain analyze delete from email_rank where project_id=25 and id in +(select id from NewRetires); + + Index Scan using email_rank__day_rank on email_rank +(cost=0.00..9003741627715.16 rows=45019 width=6) (actual time=408.12..9688.37 rows=3 loops=1) + Index Cond: (project_id = 25) + Filter: (subplan) + SubPlan + -> Seq Scan on newretires (cost=100000000.00..100000020.00 rows=1000 width=4) (actual time=0.01..0.05 rows=5 loops=91834) + Total runtime: 9689.86 msec + +But, there's already an index that would fit the bill here perfectly: + + Table "public.email_rank" + Column | Type | Modifiers +-----------------------+---------+-------------------- + project_id | integer | not null + id | integer | not null + first_date | date | not null + last_date | date | not null + day_rank | integer | not null default 0 + day_rank_previous | integer | not null default 0 + overall_rank | integer | not null default 0 + overall_rank_previous | integer | not null default 0 + work_today | bigint | not null default 0 + work_total | bigint | not null default 0 +Indexes: email_rank_pkey primary key btree (project_id, id), + email_rank__day_rank btree (project_id, day_rank), + email_rank__overall_rank btree (project_id, overall_rank) + +Why isn't it using email_rank_pkey instead of using day_rank then a +filter? The original query on sybase (see below) is essentially instant, +because it's using the index of (project_id, id), so it doesn't have to +read the whole table. + +stats=> select project_id,count(*) from email_rank group by project_id; + project_id | count +------------+-------- + 5 | 327856 + 8 | 28304 + 24 | 34622 + 25 | 91834 + 205 | 331464 + +Also, changing the WHERE IN to a WHERE EXISTS in the delete is +substantially faster in this case (3.5 seconds as opposed to 9); it +would be nice if the optimizer could rewrite the query on-the-fly. I +started looking into this in the first place because the original query +was taking 6-10 seconds, which seemed too long... + +Original query: +DELETE FROM Email_Rank + WHERE project_id = :ProjectID + AND id IN (SELECT id + FROM STATS_Participant sp + WHERE retire_to >= 1 + AND retire_date = (SELECT last_date FROM Project_statsrun WHERE project_id = :ProjectID) + ) +; + +I tried changing this to an EXISTS and it takes over a minute. So in +this case, the range of runtimes is ~4 seconds (building the temp table +takes ~0.25 seconds) to over a minute. +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 14:32:47 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2B0BC475D91 + for ; + Mon, 28 Apr 2003 14:32:46 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 7700E475B47 + for ; + Mon, 28 Apr 2003 14:32:44 -0400 (EDT) +Received: (qmail 96396 invoked by uid 1001); 28 Apr 2003 18:32:44 -0000 +Date: Mon, 28 Apr 2003 13:32:44 -0500 +From: "Jim C. Nasby" +To: pgsql-performance@postgresql.org +Subject: Re: How to get the optimizer to use an index with multiple fields +Message-ID: <20030428133244.K66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030428132143.J66185@flake.decibel.org> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: <20030428132143.J66185@flake.decibel.org>; + from jim@nasby.net on Mon, Apr 28, 2003 at 01:21:43PM -0500 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/232 +X-Sequence-Number: 1738 + +On Mon, Apr 28, 2003 at 01:21:43PM -0500, Jim C. Nasby wrote: +> I tried changing this to an EXISTS and it takes over a minute. So in +> this case, the range of runtimes is ~4 seconds (building the temp table +> takes ~0.25 seconds) to over a minute. + +BTW, I forgot to mention that building the temp table only takes 0.25 +seconds if I first disable sequential scans. :/ +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 16:04:10 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 0DBEB475B47 + for ; + Mon, 28 Apr 2003 16:04:09 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id 2C880474E42 + for ; + Mon, 28 Apr 2003 16:04:08 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.9/8.12.9) with ESMTP id h3SK1hD2003167; + Mon, 28 Apr 2003 14:01:43 -0600 (MDT) +Date: Mon, 28 Apr 2003 13:52:57 -0600 (MDT) +From: "scott.marlowe" +To: "Jim C. Nasby" +Cc: +Subject: Re: How to get the optimizer to use an index with multiple +In-Reply-To: <20030428132143.J66185@flake.decibel.org> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailScanner: Found to be clean +X-MailScanner-SpamCheck: +X-Spam-Status: No, hits=-31.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/233 +X-Sequence-Number: 1739 + +On Mon, 28 Apr 2003, Jim C. Nasby wrote: + +> select id into temp NewRetires from stats_participant where retire_to>=1 +> AND retire_date = (SELECT last_date FROM Project_statsrun WHERE +> project_id = :ProjectID); +> +> results in a table with 5 values... +> +> explain analyze delete from email_rank where project_id=25 and id in +> (select id from NewRetires); +> +> Index Scan using email_rank__day_rank on email_rank +> (cost=0.00..9003741627715.16 rows=45019 width=6) (actual time=408.12..9688.37 rows=3 loops=1) +> Index Cond: (project_id = 25) +> Filter: (subplan) +> SubPlan +> -> Seq Scan on newretires (cost=100000000.00..100000020.00 rows=1000 width=4) (actual time=0.01..0.05 rows=5 loops=91834) +> Total runtime: 9689.86 msec +> +> But, there's already an index that would fit the bill here perfectly: +> +> Table "public.email_rank" +> Column | Type | Modifiers +> -----------------------+---------+-------------------- +> project_id | integer | not null +> id | integer | not null +> first_date | date | not null +> last_date | date | not null +> day_rank | integer | not null default 0 +> day_rank_previous | integer | not null default 0 +> overall_rank | integer | not null default 0 +> overall_rank_previous | integer | not null default 0 +> work_today | bigint | not null default 0 +> work_total | bigint | not null default 0 +> Indexes: email_rank_pkey primary key btree (project_id, id), +> email_rank__day_rank btree (project_id, day_rank), +> email_rank__overall_rank btree (project_id, overall_rank) +> +> Why isn't it using email_rank_pkey instead of using day_rank then a +> filter? The original query on sybase (see below) is essentially instant, +> because it's using the index of (project_id, id), so it doesn't have to +> read the whole table. + +It looks like the seq scan is newretires up there, from your 'id in +(select id from NewRetires);' part of your query. I.e. the where in() has +to be done first, and the query planner has no stats on that table, so it +assumes a seq scan will be faster in case we need the whole thing anyway. + +Try adding an analyze newretires in there between the two queries. + +No clue as to why it's choosing one index over the other. I don't think +that really matters a lot, it's the seq scan on the temp table that is +taking your time on this. + + +From pgsql-performance-owner@postgresql.org Mon Apr 28 18:54:45 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9DAB3475FC8 + for ; + Mon, 28 Apr 2003 18:54:42 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 7FEA8475F39 + for ; + Mon, 28 Apr 2003 18:54:36 -0400 (EDT) +Received: (qmail 6715 invoked by uid 1001); 28 Apr 2003 22:54:39 -0000 +Date: Mon, 28 Apr 2003 17:54:39 -0500 +From: "Jim C. Nasby" +To: "scott.marlowe" +Cc: pgsql-performance@postgresql.org +Subject: Re: How to get the optimizer to use an index with multiple +Message-ID: <20030428175439.L66185@flake.decibel.org> +Reply-To: jim@nasby.net +References: <20030428132143.J66185@flake.decibel.org> + +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +In-Reply-To: ; + from scott.marlowe@ihs.com on Mon, Apr 28, 2003 at 01:52:57PM + -0600 +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-39.4 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, + USER_AGENT_MUTT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/234 +X-Sequence-Number: 1740 + +On Mon, Apr 28, 2003 at 01:52:57PM -0600, scott.marlowe wrote: +> On Mon, 28 Apr 2003, Jim C. Nasby wrote: +> +> > select id into temp NewRetires from stats_participant where retire_to>=1 +> > AND retire_date = (SELECT last_date FROM Project_statsrun WHERE +> > project_id = :ProjectID); +> > +> > results in a table with 5 values... +> > +> > explain analyze delete from email_rank where project_id=25 and id in +> > (select id from NewRetires); +> > +> > Index Scan using email_rank__day_rank on email_rank +> > (cost=0.00..9003741627715.16 rows=45019 width=6) (actual time=408.12..9688.37 rows=3 loops=1) +> > Index Cond: (project_id = 25) +> > Filter: (subplan) +> > SubPlan +> > -> Seq Scan on newretires (cost=100000000.00..100000020.00 rows=1000 width=4) (actual time=0.01..0.05 rows=5 loops=91834) +> > Total runtime: 9689.86 msec +> > +> > But, there's already an index that would fit the bill here perfectly: +> > +> > Table "public.email_rank" +> > Column | Type | Modifiers +> > -----------------------+---------+-------------------- +> > project_id | integer | not null +> > id | integer | not null +> > first_date | date | not null +> > last_date | date | not null +> > day_rank | integer | not null default 0 +> > day_rank_previous | integer | not null default 0 +> > overall_rank | integer | not null default 0 +> > overall_rank_previous | integer | not null default 0 +> > work_today | bigint | not null default 0 +> > work_total | bigint | not null default 0 +> > Indexes: email_rank_pkey primary key btree (project_id, id), +> > email_rank__day_rank btree (project_id, day_rank), +> > email_rank__overall_rank btree (project_id, overall_rank) +> > +> > Why isn't it using email_rank_pkey instead of using day_rank then a +> > filter? The original query on sybase (see below) is essentially instant, +> > because it's using the index of (project_id, id), so it doesn't have to +> > read the whole table. +> +> It looks like the seq scan is newretires up there, from your 'id in +> (select id from NewRetires);' part of your query. I.e. the where in() has +> to be done first, and the query planner has no stats on that table, so it +> assumes a seq scan will be faster in case we need the whole thing anyway. +> +> Try adding an analyze newretires in there between the two queries. +> +> No clue as to why it's choosing one index over the other. I don't think +> that really matters a lot, it's the seq scan on the temp table that is +> taking your time on this. + +There's no index at all on the temporary table; I fully expect it to +seqscan than. :) The issue is the choice of index on email_rank. It's +only going to hit at most 5 rows in email_rank (which it should be able +to figure out based on newretires and the fact that email_rank_pkey is +unique. I didn't show it, but I did run analyze on the temporary table +(why it doesn't have statistics I don't know...) +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-advocacy-owner@postgresql.org Tue Apr 29 00:48:41 2003 +X-Original-To: pgsql-advocacy@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 80A5D476022; Tue, 29 Apr 2003 00:48:38 -0400 (EDT) +Received: from neuromancer.ctlno.com (unknown [208.13.35.90]) + by postgresql.org (Postfix) with ESMTP + id BEA5D475F26; Tue, 29 Apr 2003 00:48:02 -0400 (EDT) +Received: from [192.168.1.10] (ool-4352919e.dyn.optonline.net [67.82.145.158]) + by neuromancer.ctlno.com (8.12.6/8.12.6) with ESMTP id + h3T5jfkN017013; Tue, 29 Apr 2003 00:45:41 -0500 +Subject: Re: [HACKERS] Changing the default configuration +From: "Matthew T. O'Connor" +To: Tatsuo Ishii +Cc: tgl@sss.pgh.pa.us, justin@postgresql.org, josh@agliodbs.com, + merlin.moncure@rcsonline.com, pgsql-hackers@postgresql.org, + pgsql-advocacy@postgresql.org +In-Reply-To: <20030212.101000.74752335.t-ishii@sra.co.jp> +References: <26582.1044984365@sss.pgh.pa.us> + <3E493415.9090004@postgresql.org> <26850.1044985975@sss.pgh.pa.us> + <20030212.101000.74752335.t-ishii@sra.co.jp> +Content-Type: text/plain +Organization: Zeut Tech +Message-Id: <1051591298.7047.11.camel@zeutrh9> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) +Date: 29 Apr 2003 00:41:38 -0400 +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by amavisd-milter (http://amavis.org/) +X-Spam-Status: No, hits=-36.7 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/177 +X-Sequence-Number: 1118 + +On Tue, 2003-02-11 at 20:10, Tatsuo Ishii wrote: +> Sigh. People always complain "pgbench does not reliably producing +> repeatable numbers" or something then say "that's because pgbench's +> transaction has too much contention on the branches table". So I added +> -N option to pgbench which makes pgbench not to do any UPDATE to +> the branches table. But still people continue to complian... + +What exactly does the -N option do? I see no mention of it in the +README.pgbench, which might be part of reason people "continue to +complain". + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 03:01:27 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id A4251476375 + for ; + Tue, 29 Apr 2003 03:01:24 -0400 (EDT) +Received: from rtlocal.trade-india.com (unknown [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id 6051447632B + for ; + Tue, 29 Apr 2003 03:00:42 -0400 (EDT) +Received: (qmail 6406 invoked from network); 29 Apr 2003 07:00:43 -0000 +Received: from unknown (HELO system67.trade-india-local.com) (unknown) + by unknown with SMTP; 29 Apr 2003 07:00:43 -0000 +From: Rajesh Kumar Mallah +Organization: Infocom Network Limited +To: pgsql-performance@postgresql.org +Subject: Is 292 inserts/sec acceptable performance ? +Date: Tue, 29 Apr 2003 12:31:09 +0530 +User-Agent: KMail/1.5 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304291231.09842.mallah@trade-india.com> +X-Spam-Status: No, hits=-5.9 required=5.0 + tests=BAYES_01,NO_DNS_FOR_FROM,SIGNATURE_SHORT_SPARSE,USER_AGENT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/235 +X-Sequence-Number: 1741 + + + +Hi Can anyone tell if the case below is an acceptable +performance ? + +I have a query that returns data and creates a table +in 3 mins approx. This query is optimised and uses appropriate +indexes for the NOT EXISTS part. + +CREATE TABLE t_a as SELECT +email,country_code,city,title1,fname1,mname1,lname1,website,address,source,ifimporter, +ifexporter,ifservice,ifmanu,creation_date from general.email_bank_import +where not exists (select * from general.profile_master where +email=general.email_bank_import.email) ; +SELECT +Time: 174637.31 ms (3 mins Approx) + + + +The problem is when i try to INSERT the data into another table +it takes 23 mins Apprx to inser 412331 records the same query. + +I am providing the various details below: + +tradein_clients=# INSERT INTO general.profile_master +(email,country_code,city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexporter, +ifservice, ifmanu,creation_date) SELECT email,country_code, +city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexporter,ifservice, +ifmanu,creation_date from general.email_bank_import where not exists +(select * from general.profile_master where +email=general.email_bank_import.email) ; +INSERT 0 412331 +Time: 1409510.63 ms + + +The table destination general.profile_master in which +data is being inserted was already having 184424 records +before the INSERT the VACUUM FULL ANALZYE VERBOSE output was: + +tradein_clients=# VACUUM FULL VERBOSE ANALYZE profile_master ; +INFO: --Relation general.profile_master-- +INFO: Pages 9161: Changed 0, reaped 8139, Empty 0, New 0; Tup 184424: Vac 72, +Keep/VTL 0/0, UnUsed 118067, MinLen 154, MaxLen 2034; Re-using: Free/Avail. +Space 708064/337568; EndEmpty/Avail. Pages 0/1669. + CPU 0.17s/0.03u sec elapsed 0.21 sec. +INFO: Index profile_master_email: Pages 8921; Tuples 184424: Deleted 72. + CPU 0.15s/0.21u sec elapsed 0.37 sec. +INFO: Index profile_master_profile_id_pkey: Pages 1295; Tuples 184424: +Deleted 72. + CPU 0.03s/0.10u sec elapsed 0.16 sec. +INFO: Rel profile_master: Pages: 9161 --> 9161; Tuple(s) moved: 0. + CPU 0.44s/0.98u sec elapsed 15.79 sec. +INFO: --Relation pg_toast.pg_toast_163041602-- +INFO: Pages 31: Changed 0, reaped 1, Empty 0, New 0; Tup 187: Vac 0, Keep/VTL +0/0, UnUsed 2, MinLen 50, MaxLen 2034; Re-using: Free/Avail. Space +24800/24788; EndEmpty/Avail. Pages 0/30. + CPU 0.00s/0.00u sec elapsed 3.04 sec. +INFO: Index pg_toast_163041602_index: Pages 2; Tuples 187: Deleted 0. + CPU 0.00s/0.00u sec elapsed 0.49 sec. +INFO: Rel pg_toast_163041602: Pages: 31 --> 31; Tuple(s) moved: 0. + CPU 0.00s/0.00u sec elapsed 0.00 sec. + +INFO: Analyzing general.profile_master +VACUUM +It was already vacuumed once. + +Index Info: Only two indexes were existing + +tradein_clients=# \d profile_master + Table "general.profile_master" ++--------------------+------------------------+------- +| Column | Type | ++--------------------+------------------------+------- +| profile_id | integer | +| userid | integer | +| co_name | character varying(100) | +| address | text | +| pincode | character varying(20) | +| city | character varying(50) | +| country_code | character varying(2) | +| phone_no | character varying(100) | +| fax_no | character varying(100) | +| email | character varying(100) | +| website | character varying(100) | +| title1 | character varying(15) | +| fname1 | character varying(200) | +| mname1 | character varying(30) | +| lname1 | character varying(30) | +| desg1 | character varying(100) | +| mobile | character varying(20) | +| title2 | character varying(15) | +| fname2 | character varying(30) | +| mname2 | character varying(30) | +| lname2 | character varying(30) | +| desg2 | character varying(100) | +| mobile2 | character varying(20) | +| co_branches | character varying(100) | +| estd | smallint | +| staff | integer | +| prod_exp | text | +| prod_imp | text | +| prod_manu | text | +| prod_serv | text | +| ifexporter | boolean | not null +| ifimporter | boolean | not null +| ifservice | boolean | not null +| ifmanu | boolean | not null +| bankers | character varying(255) | +| imp_exp_code | character varying(100) | +| memb_affil | character varying(255) | +| std_cert | character varying(255) | +| branch_id | integer | +| area_id | integer | +| annual_turn | numeric | +| annual_currency | character varying(5) | +| exp_turn | numeric | +| exp_currency | character varying(5) | +| imp_turn | numeric | +| imp_currency | character varying(5) | +| creation_date | integer | not null +| profile_status | character varying(10) | +| source | character varying(20) | not null +| company_id | integer | +| eyp_list_id | integer | +| iid_list_id | integer | +| ip_list_id | integer | +| catalog_company_id | integer | +| extra_attributes | boolean | not null default false +| +------------------------------------------------------------------------ +Indexes: profile_master_profile_id_pkey primary key btree (profile_id), + profile_master_email btree (email) + + +-- +Rajesh Kumar Mallah, +Project Manager (Development) +Infocom Network Limited, New Delhi +phone: +91(11)6152172 (221) (L) ,9811255597 (M) + +Visit http://www.trade-india.com , +India's Leading B2B eMarketplace. + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 03:26:18 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 95599476022 + for ; + Tue, 29 Apr 2003 03:26:16 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 61F76476022 + for ; + Tue, 29 Apr 2003 03:25:39 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id h3T7PcL27972 + for ; Tue, 29 Apr 2003 12:55:38 +0530 +Received: from daithan.intranet.pspl.co.in (daithan.intranet.pspl.co.in + [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id h3T7Pc427967 + for ; Tue, 29 Apr 2003 12:55:38 +0530 +From: Shridhar Daithankar +To: pgsql-performance@postgresql.org +Subject: Re: Is 292 inserts/sec acceptable performance ? +Date: Tue, 29 Apr 2003 12:55:15 +0530 +User-Agent: KMail/1.5.1 +References: <200304291231.09842.mallah@trade-india.com> +In-Reply-To: <200304291231.09842.mallah@trade-india.com> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304291255.15558.shridhar_daithankar@nospam.persistent.co.in> +X-Spam-Status: No, hits=-37.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/236 +X-Sequence-Number: 1742 + +On Tuesday 29 April 2003 12:31, Rajesh Kumar Mallah wrote: +> Hi Can anyone tell if the case below is an acceptable +> performance ? +> +> I have a query that returns data and creates a table +> in 3 mins approx. This query is optimised and uses appropriate +> indexes for the NOT EXISTS part. +> +> CREATE TABLE t_a as SELECT +> email,country_code,city,title1,fname1,mname1,lname1,website,address,source, +>ifimporter, ifexporter,ifservice,ifmanu,creation_date from +> general.email_bank_import where not exists (select * from +> general.profile_master where +> email=general.email_bank_import.email) ; +> SELECT +> Time: 174637.31 ms (3 mins Approx) +> +> +> +> The problem is when i try to INSERT the data into another table +> it takes 23 mins Apprx to inser 412331 records the same query. +> +> I am providing the various details below: +> +> tradein_clients=# INSERT INTO general.profile_master +> (email,country_code,city,title1,fname1,mname1,lname1,website,address,source +>,ifimporter,ifexporter, ifservice, ifmanu,creation_date) SELECT +> email,country_code, +> city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexport +>er,ifservice, ifmanu,creation_date from general.email_bank_import where +> not exists (select * from general.profile_master where +> email=general.email_bank_import.email) ; +> INSERT 0 412331 +> Time: 1409510.63 ms + +I am not sure if this would help but why you have to use all the fields in not +exists clause? How about not exists for a name or profile_id? Would it be any +faster + +I assume if there are two records with half the info same, then not exists for +1 field with index would be significantly faster than 10 fields. + +HTH + + Shridhar + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 05:03:38 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D972D4758F1 + for ; + Tue, 29 Apr 2003 05:03:35 -0400 (EDT) +Received: from web41213.mail.yahoo.com (web41213.mail.yahoo.com + [66.218.93.46]) + by postgresql.org (Postfix) with SMTP id E308447635B + for ; + Tue, 29 Apr 2003 05:02:59 -0400 (EDT) +Message-ID: <20030429090301.13152.qmail@web41213.mail.yahoo.com> +Received: from [68.4.184.46] by web41213.mail.yahoo.com via HTTP; + Tue, 29 Apr 2003 02:03:01 PDT +Date: Tue, 29 Apr 2003 02:03:01 -0700 (PDT) +From: Rob Messer +Subject: Optimizer not using index when it should +To: pgsql-performance@postgresql.org +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Spam-Status: No, hits=-4.5 required=5.0 tests=BAYES_10,NO_DNS_FOR_FROM + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/237 +X-Sequence-Number: 1743 + +Like some other recent messages, this one is about getting postgresql +to use an index that it seems it should clearly use. (But this one has +nothing to do with count(*)). + +Here is my table: + + Column | Type | Modifiers +--------------+-----------------------------+----------- + dsid | character varying(20) | not null + recid | numeric(8,0) | not null + trans_id | character varying(16) | not null + status | character varying(1) | + init_ts | timestamp without time zone | + last_ts | timestamp without time zone | + last_form_id | character varying(8) | + secval | character varying(20) | +Indexes: ds_rec1 unique btree (recid), + ds_rec2 btree (dsid) + +Here is my version info: + PostgreSQL 7.3.2 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.2 +20020903 (Red Hat Linux 8.0 3.2-7) + +Currently the table ds_record has about 250,000 records in it. Of +those, about 3000 have dsid = 'starz'. When I need to look up all the +recids with this dsid in ds_record, I have the following simple query: + +select recid from ds_record where dsid = 'startz'; + +But it doesn't use the index ds_rec2 on dsid. Here is the explain +analyze output: + +intellis2=> explain analyze select recid from ds_record where dsid = +'starz'; + QUERY PLAN + +-------------------------------------------------------------------------------------------------------------- + Seq Scan on ds_record (cost=0.00..6186.21 rows=3484 width=12) (actual +time=10.60..408.12 rows=3484 loops=1) + Filter: (dsid = 'starz'::character varying) + Total runtime: 410.14 msec +(3 rows) + +but if I turn off seqscan I get this: + +intellis2=> set enable_seqscan=off; +SET +intellis2=> explain analyze select recid from ds_record where dsid = +'starz'; + QUERY PLAN + +---------------------------------------------------------------------------------------------------------------------------- + Index Scan using ds_rec2 on ds_record (cost=0.00..7185.47 rows=3484 +width=12) +(actual time=0.17..12.94 rows=3484 loops=1) + Index Cond: (dsid = 'starz'::character varying) + Total runtime: 14.97 msec +(3 rows) + +so it is faster by more than a factor of 25 to use the index. The +problem gets worse when I add a join to the table. + +I have tried the following: + +alter table ds_record alter dsid set statistics 1000; +vacuum analyze ds_record; +drop index ds_rec2; +CREATE INDEX ds_rec2 ON ds_record USING btree (dsid); + +But to no avail, I get the same results. + +Interestingly, for queries that return fewer rows it does use the +correct index. For example, dsid="mapbuy2" appears about 500 times in +ds_record. Here is the explain out there (with enable_seqscan back +on): + +intellis2=> explain analyze select recid from ds_record where dsid = +'mapbuy2'; + QUERY PLAN + +------------------------------------------------------------------------------------------------------------------------- + Index Scan using ds_rec2 on ds_record (cost=0.00..1351.17 rows=522 +width=12) (actual time=0.18..4.31 rows=522 loops=1) + Index Cond: (dsid = 'mapbuy2'::character varying) + Total runtime: 4.68 msec + +To me it seems that the threshold for doing a table scan is wrong -- +when the rows retrieved are about 1.25% of the table it does a scan. + +What can I do to fix this -- is there something I am missing about +setting statistics or some configuration variable I can change? Any +insights would be greatly appreciated. Thank you, + +Rob Messer + + + +__________________________________ +Do you Yahoo!? +The New Yahoo! Search - Faster. Easier. Bingo. +http://search.yahoo.com + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 07:12:36 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E02414763C2 + for ; + Tue, 29 Apr 2003 07:12:34 -0400 (EDT) +Received: from rtlocal.trade-india.com (unknown [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id F3D514763C2 + for ; + Tue, 29 Apr 2003 07:11:53 -0400 (EDT) +Received: (qmail 21477 invoked from network); 29 Apr 2003 11:11:56 -0000 +Received: from unknown (HELO system67.trade-india-local.com) (unknown) + by unknown with SMTP; 29 Apr 2003 11:11:56 -0000 +From: Rajesh Kumar Mallah +Organization: Infocom Network Limited +To: Shridhar Daithankar , + pgsql-performance@postgresql.org +Subject: Re: Is 292 inserts/sec acceptable performance ? +Date: Tue, 29 Apr 2003 16:42:24 +0530 +User-Agent: KMail/1.5 +References: <200304291231.09842.mallah@trade-india.com> + <200304291255.15558.shridhar_daithankar@nospam.persistent.co.in> +In-Reply-To: <200304291255.15558.shridhar_daithankar@nospam.persistent.co.in> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304291642.24543.mallah@trade-india.com> +X-Spam-Status: No, hits=-31.8 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + SIGNATURE_SHORT_SPARSE,USER_AGENT autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/238 +X-Sequence-Number: 1744 + + +Yeah even 1 feild can be given in the NOT EXISTS part. +bUt i vaugely recally tom saying that it does not matter +and internally its converted to "select * form tab" from, + +correct me if i am recalling wrong. + +in anycase the CREATE TABLE part is working fine ie +in 3 mins the select and table creation is over. + +Is the continuously entering data slowing down the NO EXISTS +part ? in any case that inserts are supposed to be invisible +to the NOT EXISTS part i guess. + + + + +regds +mallah. + + +On Tuesday 29 Apr 2003 12:55 pm, Shridhar Daithankar wrote: +> On Tuesday 29 April 2003 12:31, Rajesh Kumar Mallah wrote: +> > Hi Can anyone tell if the case below is an acceptable +> > performance ? +> > +> > I have a query that returns data and creates a table +> > in 3 mins approx. This query is optimised and uses appropriate +> > indexes for the NOT EXISTS part. +> > +> > CREATE TABLE t_a as SELECT +> > email,country_code,city,title1,fname1,mname1,lname1,website,address,sourc +> >e, ifimporter, ifexporter,ifservice,ifmanu,creation_date from +> > general.email_bank_import where not exists (select * from +> > general.profile_master where +> > email=general.email_bank_import.email) ; +> > SELECT +> > Time: 174637.31 ms (3 mins Approx) +> > +> > +> > +> > The problem is when i try to INSERT the data into another table +> > it takes 23 mins Apprx to inser 412331 records the same query. +> > +> > I am providing the various details below: +> > +> > tradein_clients=# INSERT INTO general.profile_master +> > (email,country_code,city,title1,fname1,mname1,lname1,website,address,sour +> >ce ,ifimporter,ifexporter, ifservice, ifmanu,creation_date) SELECT +> > email,country_code, +> > city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexpo +> >rt er,ifservice, ifmanu,creation_date from general.email_bank_import +> > where not exists (select * from general.profile_master where +> > email=general.email_bank_import.email) ; +> > INSERT 0 412331 +> > Time: 1409510.63 ms +> +> I am not sure if this would help but why you have to use all the fields in +> not exists clause? How about not exists for a name or profile_id? Would it +> be any faster +> +> I assume if there are two records with half the info same, then not exists +> for 1 field with index would be significantly faster than 10 fields. +> +> HTH +> +> Shridhar +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 5: Have you checked our extensive FAQ? +> +> http://www.postgresql.org/docs/faqs/FAQ.html + +-- +Rajesh Kumar Mallah, +Project Manager (Development) +Infocom Network Limited, New Delhi +phone: +91(11)6152172 (221) (L) ,9811255597 (M) + +Visit http://www.trade-india.com , +India's Leading B2B eMarketplace. + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 07:24:34 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E89A74763BA + for ; + Tue, 29 Apr 2003 07:24:32 -0400 (EDT) +Received: from rtlocal.trade-india.com (mail-relay.trade-india.com + [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id 2E0084763C2 + for ; + Tue, 29 Apr 2003 07:23:54 -0400 (EDT) +Received: (qmail 21824 invoked from network); 29 Apr 2003 11:24:32 -0000 +Received: from unknown (HELO system67.trade-india-local.com) (unknown) + by unknown with SMTP; 29 Apr 2003 11:24:32 -0000 +From: Rajesh Kumar Mallah +Organization: Infocom Network Limited +To: pgsql-performance@postgresql.org +Subject: profiling plpgsql functions.. +Date: Tue, 29 Apr 2003 16:55:01 +0530 +User-Agent: KMail/1.5 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304291655.01035.mallah@trade-india.com> +X-Spam-Status: No, hits=-5.9 required=5.0 + tests=BAYES_01,NO_DNS_FOR_FROM,SIGNATURE_SHORT_SPARSE,USER_AGENT + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/239 +X-Sequence-Number: 1745 + + + +Is printing timeofday() at various points a good idea +of profiling plpgsql functions? + +also is anything wrong with following fragment ? +RAISE INFO '' % , message here ... '' , timeofday() ; + + +regds +mallah. + +-- +Rajesh Kumar Mallah, +Project Manager (Development) +Infocom Network Limited, New Delhi +phone: +91(11)6152172 (221) (L) ,9811255597 (M) + +Visit http://www.trade-india.com , +India's Leading B2B eMarketplace. + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 09:35:29 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 064EF4763E7; Tue, 29 Apr 2003 09:35:25 -0400 (EDT) +Received: from mail.deltav.hu (mail.deltav.hu [213.163.0.192]) + by postgresql.org (Postfix) with ESMTP + id 1DCB34763E9; Tue, 29 Apr 2003 09:34:48 -0400 (EDT) +Received: from fejleszt2 ([213.163.10.103]) by mail.deltav.hu + (Netscape Messaging Server 3.6) with SMTP id AAA4691; + Tue, 29 Apr 2003 15:34:49 +0200 +Message-ID: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> +From: "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" +To: , +Subject: Query Plan far worse in 7.3.2 than 7.2.1 +Date: Tue, 29 Apr 2003 15:01:21 +0200 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-2" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-1.8 required=5.0 tests=BAYES_20,NO_DNS_FOR_FROM + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/241 +X-Sequence-Number: 1747 + +Dear Gurus, + +A nasty query and its EXPLAINs are here. Read on at your own risk :) + +ABSTRACT: + +Search for the strings "looping index scan" and "loops=2310" in this +message. + +DETAILS: + +Yesteray, I spent two hours to optimize a view in postgresql 7.2.1. My +problem was that one of the index scans executed 2358 times, which is (as +far as I can consider) equal to 2x1179, where 2 is the #rows in a subquery, +and 1179 is the total #rows in the table of the index scan ("arfolyam"). + +Finally I managed to put it as deep in the query as possible, to reduce the +loops to the number of query result rows (12) + +However, when I tried the same query in 7.3.2, it first complained about a +missing FROM clause and a missing GROUP BY for a field. I managed to +eliminate both without affecting 7.2.1 performance, but in 7.3.2, there are +still those 2300+ loops of the index scan. + +I ask your kind help, explanation or references to documented similar cases. + +Below is the query and the two explains. Please forgive the raw format. +If you need further info (such as table defs), I'd be glad to help. + +Note that the two databases are not exactly the same but very similar (they +where the same 2 weeks ago, but data changes occured in both, independently) +and I don't think these differences should affect the planner. + +Yours, +G. +-- +while (!asleep()) sheep++; + +---------------------------- QUERY ----------------------------------- +SELECT *, + kerekit_penznem (netto_ertek*(afa_szazalek/100), penznem) AS afa_ertek, + kerekit_penznem (netto_ertek*(1+afa_szazalek/100), penznem) AS +brutto_ertek +FROM ( + SELECT szamla, + kerekit_penznem( + elsodl_netto_ertek*COALESCE(deka,1)/COALESCE(dekb,1), penznem) + AS netto_ertek, + konyvelesi_tetelcsoport, afa, afa_szazalek, penznem + FROM + (SELECT szt.szamla, + kerekit_penznem(sum(szt.netto_egysegar * szt.mennyiseg), penznem) + AS elsodl_netto_ertek, + konyvelesi_tetelcsoport(szt.szamla, szt.tetelszam) + AS konyvelesi_tetelcsoport, + szt.afa, afa.ertek AS afa_szazalek, + szamla.penznem AS sz_penznem, + szamla.teljesites AS sz_teljesites, + arf_a.deviza_kozeparfolyam as deka, + arf_b.deviza_kozeparfolyam as dekb, + foo_valuta AS penznem + FROM szamla_tetele szt + LEFT JOIN szamla ON (szamla = szamla.az) + LEFT JOIN afa ON (afa.az = szt.afa) + LEFT JOIN arfolyam arf_a + ON (arf_a.ervenyes = + (SELECT ervenyes FROM arfolyam + WHERE ervenyes<=szamla.teljesites AND valuta = szamla.penznem + ORDER BY 1 DESC LIMIT 1) + AND szamla.penznem=arf_a.valuta) + JOIN + (SELECT az AS foo_valuta FROM valuta) AS valuta ON (true) + LEFT JOIN arfolyam arf_b + ON (arf_b.valuta=foo_valuta AND + arf_b.ervenyes = +-- this is the looping index scan -- + (SELECT ervenyes FROM arfolyam + WHERE ervenyes<=szamla.teljesites AND valuta = foo_valuta + ORDER BY 1 DESC LIMIT 1) +-- end of looping index scan -- + ) + WHERE (NOT szt.archiv) AND + (foo_valuta = 4 or arf_b.valuta notnull + ) + GROUP BY szt.szamla, konyvelesi_tetelcsoport, szt.afa, + sz_penznem, sz_teljesites, afa.ertek, + arf_a.deviza_kozeparfolyam, arf_b.deviza_kozeparfolyam, foo_valuta, +penznem + ) foo +) bar +WHERE szamla=2380; + +---------------------------- 7.2.1 PLAN ------------------------------ +Subquery Scan foo (cost=488.97..490.94 rows=8 width=104) (actual +time=94.77..109.10 rows=12 loops=1) +-> Aggregate (cost=488.97..490.94 rows=8 width=104) (actual +time=89.29..92.05 rows=12 loops=1) + -> Group (cost=488.97..490.74 rows=79 width=104) (actual +time=88.13..88.59 rows=12 loops=1) + -> Sort (cost=488.97..488.97 rows=79 width=104) (actual time=88.09..88.13 +rows=12 loops=1) + -> Nested Loop (cost=1.05..486.50 rows=79 width=104) (actual +time=28.23..86.20 rows=12 loops=1) + -> Nested Loop (cost=1.05..150.19 rows=79 width=84) (actual +time=12.68..25.41 rows=12 loops=1) + -> Nested Loop (cost=1.05..135.52 rows=13 width=80) (actual +time=12.60..24.80 rows=2 loops=1) + -> Hash Join (cost=1.05..79.59 rows=13 width=60) (actual +time=0.55..0.80 rows=2 loops=1) + -> Nested Loop (cost=0.00..78.31 rows=13 width=46) (actual +time=0.23..0.42 rows=2 loops=1) + -> Index Scan using szml_ttl_szml on szamla_tetele szt +(cost=0.00..3.51 rows=13 width=34) (actual time=0.11..0.16 rows=2 loops=1) + -> Index Scan using szamla_az_key on szamla (cost=0.00..5.70 rows=1 +width=12) (actual time=0.07..0.09 rows=1 loops=2) + -> Hash (cost=1.04..1.04 rows=4 width=14) (actual time=0.14..0.14 +rows=0 loops=1) + -> Seq Scan on afa (cost=0.00..1.04 rows=4 width=14) (actual +time=0.08..0.11 rows=4 loops=1) + -> Index Scan using arfolyam_ervenyes on arfolyam arf_a +(cost=0.00..3.63 rows=3 width=20) (actual time=0.01..0.01 rows=0 loops=2) + SubPlan + -> Limit (cost=0.00..0.17 rows=1 width=4) (actual time=11.92..11.92 +rows=0 loops=2) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam +(cost=0.00..13.30 rows=79 width=4) (actual time=11.90..11.90 rows=0 loops=2) + -> Limit (cost=0.00..0.17 rows=1 width=4) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam +(cost=0.00..13.30 rows=79 width=4) + -> Seq Scan on valuta (cost=0.00..1.06 rows=6 width=4) (actual +time=0.02..0.11 rows=6 loops=2) + -> Index Scan using arfolyam_ervenyes on arfolyam arf_b (cost=0.00..3.63 +rows=3 width=20) (actual time=0.04..0.10 rows=3 loops=12) + SubPlan + -> Limit (cost=0.00..0.17 rows=1 width=4) (actual time=4.35..4.39 +rows=1 loops=12) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam +(cost=0.00..13.30 rows=79 width=4) (actual time=4.33..4.37 rows=2 loops=12) + -> Limit (cost=0.00..0.17 rows=1 width=4) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam +(cost=0.00..13.30 rows=79 width=4) +Total runtime: 111.48 msec + +---------------------------- 7.3.2 PLAN ------------------------------ + Subquery Scan foo (cost=14542.01..15448.46 rows=3022 width=123) (actual +time=2264.36..2282.17 rows=12 loops=1) + -> Aggregate (cost=14542.01..15448.46 rows=3022 width=123) (actual +time=2257.70..2261.08 rows=12 loops=1) + -> Group (cost=14542.01..15372.92 rows=30215 width=123) (actual +time=2256.31..2256.84 rows=12 loops=1) + -> Sort (cost=14542.01..14617.55 rows=30215 width=123) +(actual time=2256.27..2256.31 rows=12 loops=1) + Sort Key: szt.szamla, +konyvelesi_tetelcsoport(szt.szamla, szt.tetelszam), szt.afa, szamla.penznem, +szamla.teljesites, afa.ertek, arf_a.deviza_kozeparfolyam, +arf_b.deviza_kozeparfolyam, public.valuta.az + -> Merge Join (cost=4755.50..11038.79 rows=30215 +width=123) (actual time=80.88..2254.96 rows=12 loops=1) + Merge Cond: ("outer".az = "inner".valuta) + Join Filter: ("inner".ervenyes = (subplan)) + Filter: (("outer".az = 4) OR ("inner".valuta IS +NOT NULL)) + -> Sort (cost=4676.19..4751.73 rows=30215 +width=103) (actual time=56.41..56.44 rows=12 loops=1) + Sort Key: public.valuta.az + -> Nested Loop (cost=433.35..1375.92 +rows=30215 width=103) (actual time=55.78..56.18 rows=12 loops=1) + -> Merge Join (cost=433.35..469.47 +rows=30 width=99) (actual time=55.68..55.72 rows=2 loops=1) + Merge Cond: ("outer".penznem = +"inner".valuta) + Join Filter: ("inner".ervenyes += (subplan)) + -> Sort (cost=354.05..354.12 +rows=30 width=79) (actual time=32.63..32.64 rows=2 loops=1) + Sort Key: szamla.penznem + -> Hash Join +(cost=121.67..353.30 rows=30 width=79) (actual time=32.37..32.49 rows=2 +loops=1) + Hash Cond: +("outer".afa = "inner".az) + -> Merge Join +(cost=120.62..352.09 rows=30 width=58) (actual time=32.07..32.16 rows=2 +loops=1) + Merge Cond: +("outer".az = "inner".szamla) + -> Sort +(cost=120.62..123.85 rows=1291 width=12) (actual time=25.62..27.62 rows=1285 +loops=1) + Sort +Key: szamla.az + -> Seq +Scan on szamla (cost=0.00..53.91 rows=1291 width=12) (actual +time=0.04..16.46 rows=1314 loops=1) + -> Index +Scan using szamla_tetele_pkey on szamla_tetele szt (cost=0.00..218.88 +rows=30 width=46) (actual time=0.13..0.18 rows=2 loops=1) + Index +Cond: (szamla = 2380) + Filter: +(NOT archiv) + -> Hash +(cost=1.04..1.04 rows=4 width=21) (actual time=0.10..0.10 rows=0 loops=1) + -> Seq Scan +on afa (cost=0.00..1.04 rows=4 width=21) (actual time=0.04..0.07 rows=4 +loops=1) + -> Sort (cost=79.30..82.19 +rows=1155 width=20) (actual time=22.93..22.93 rows=1 loops=1) + Sort Key: arf_a.valuta + -> Seq Scan on arfolyam +arf_a (cost=0.00..20.55 rows=1155 width=20) (actual time=0.03..9.66 +rows=1155 loops=1) + SubPlan + -> Limit (cost=0.00..0.16 +rows=1 width=4) (never executed) + -> Index Scan Backward +using arfolyam_ervenyes on arfolyam (cost=0.00..12.17 rows=77 width=4) +(never executed) + Index Cond: +(ervenyes <= $0) + Filter: (valuta = +$1) + -> Seq Scan on valuta +(cost=0.00..20.00 rows=1000 width=4) (actual time=0.02..0.06 rows=6 loops=2) + -> Sort (cost=79.30..82.19 rows=1155 width=20) +(actual time=21.98..27.54 rows=2309 loops=1) + Sort Key: arf_b.valuta + -> Seq Scan on arfolyam arf_b +(cost=0.00..20.55 rows=1155 width=20) (actual time=0.03..9.89 rows=1155 +loops=1) + SubPlan + -> Limit (cost=0.00..0.16 rows=1 width=4) +(actual time=0.88..0.91 rows=1 loops=2310) + -> Index Scan Backward using +arfolyam_ervenyes on arfolyam (cost=0.00..12.17 rows=77 width=4) (actual +time=0.87..0.90 rows=2 loops=2310) + Index Cond: (ervenyes <= $0) + Filter: (valuta = $2) + Total runtime: 2287.30 msec + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 09:04:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2A5CB475F00 + for ; + Tue, 29 Apr 2003 09:04:34 -0400 (EDT) +Received: from nat.inquent.com + (CPE00508b028d7d-CM00803785c5e0.cpe.net.cable.rogers.com + [24.103.22.28]) by postgresql.org (Postfix) with ESMTP id 372CB475F00 + for ; + Tue, 29 Apr 2003 09:03:58 -0400 (EDT) +Received: from [127.0.0.1] (localhost [127.0.0.1]) + by nat.inquent.com (8.12.8p1/8.12.8) with ESMTP id h3TD49Mn077441; + Tue, 29 Apr 2003 09:04:09 -0400 (EDT) (envelope-from rbt@rbt.ca) +Subject: Re: Optimizer not using index when it should +From: Rod Taylor +To: Rob Messer +Cc: Postgresql Performance +In-Reply-To: <20030429090301.13152.qmail@web41213.mail.yahoo.com> +References: <20030429090301.13152.qmail@web41213.mail.yahoo.com> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-Ovj/BN9AuBu3Q4vbTld/" +Organization: +Message-Id: <1051621449.76105.9.camel@jester> +Mime-Version: 1.0 +X-Mailer: Ximian Evolution 1.2.4 +Date: 29 Apr 2003 09:04:09 -0400 +X-Spam-Status: No, hits=-36.5 required=5.0 + tests=BAYES_10,IN_REP_TO,NO_DNS_FOR_FROM,PGP_SIGNATURE_2, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES, + USER_AGENT_XIMIAN autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/240 +X-Sequence-Number: 1746 + +--=-Ovj/BN9AuBu3Q4vbTld/ +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +> What can I do to fix this -- is there something I am missing about +> setting statistics or some configuration variable I can change? Any +> insights would be greatly appreciated. Thank you, + +If you look at the estimates for cost, the index scan is more expensive +by ~1/8th. But as you've shown, it's not. + +You might try adjusting the random_page_cost down to something more +appropriate for your hardware and situation. + +Do testing... this may cause other queries to use an index scan when +they should have been doing a sequential scan. Mistakenly using an +index can be a much more costly error (hence the high default +random_page_cost). + +--=20 +Rod Taylor + +PGP Key: http://www.rbt.ca/rbtpub.asc + +--=-Ovj/BN9AuBu3Q4vbTld/ +Content-Type: application/pgp-signature; name=signature.asc +Content-Description: This is a digitally signed message part + +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.2.1 (FreeBSD) + +iD8DBQA+rnhI6DETLow6vwwRAoncAJ457zHHTudzl3EDklw5xiUhlWiNwwCfWRwZ +hzRGx/zN3z6wKyqBDffwNmw= +=pEbG +-----END PGP SIGNATURE----- + +--=-Ovj/BN9AuBu3Q4vbTld/-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 09:53:54 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2E98A47632B + for ; + Tue, 29 Apr 2003 09:53:54 -0400 (EDT) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id 0F598475F34 + for ; + Tue, 29 Apr 2003 09:53:18 -0400 (EDT) +Received: (qmail 5861 invoked from network); 29 Apr 2003 13:53:18 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 29 Apr 2003 13:53:18 -0000 +From: "Robert John Shepherd" +To: +Subject: Best ODBC cursor and lock types for fastest reading? +Date: Tue, 29 Apr 2003 14:53:18 +0100 +Message-ID: <001701c30e56$b0964400$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-1.8 required=5.0 tests=BAYES_20,NO_DNS_FOR_FROM + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/242 +X-Sequence-Number: 1748 + +I access Postgresql through the ODBC driver, and always only read small +recordsets (never updating them) with forward cursors. + +The following options are defined in ADO with which I can create a +recordset with: + +Cursor types: +adOpenForwardOnly (what I currently use) +adOpenKeyset +adOpenDynamic +adOpenStatic + +Lock types: +adLockReadOnly +adLockPessimistic +adLockOptimistic (what I currently use) +adLockBatchOptimistic + +Do any of these offer a performance gain over others? I used to use +adLockReadOnly with MS-SQL which really sped things up but this doesn't +seem to work at all under Postgresql and I've been using +adLockOptimistic instead. + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 10:01:34 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 57D8C475F1B + for ; + Tue, 29 Apr 2003 10:01:31 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 8155B475B47 + for ; + Tue, 29 Apr 2003 10:00:55 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TE0xU6026232; + Tue, 29 Apr 2003 10:00:59 -0400 (EDT) +To: Rajesh Kumar Mallah +Cc: pgsql-performance@postgresql.org +Subject: Re: Is 292 inserts/sec acceptable performance ? +In-reply-to: <200304291231.09842.mallah@trade-india.com> +References: <200304291231.09842.mallah@trade-india.com> +Comments: In-reply-to Rajesh Kumar Mallah + message dated "Tue, 29 Apr 2003 12:31:09 +0530" +Date: Tue, 29 Apr 2003 10:00:59 -0400 +Message-ID: <26231.1051624859@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-27.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/243 +X-Sequence-Number: 1749 + +Rajesh Kumar Mallah writes: +> Hi Can anyone tell if the case below is an acceptable +> performance ? + +Not with that info. Could we see EXPLAIN ANALYZE results for both +the faster and slower cases? + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 10:18:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 2939C475F00 + for ; + Tue, 29 Apr 2003 10:18:51 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 6D86B475ADE + for ; + Tue, 29 Apr 2003 10:18:15 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TEIJU6026350; + Tue, 29 Apr 2003 10:18:19 -0400 (EDT) +To: Rod Taylor +Cc: Rob Messer , + Postgresql Performance +Subject: Re: Optimizer not using index when it should +In-reply-to: <1051621449.76105.9.camel@jester> +References: <20030429090301.13152.qmail@web41213.mail.yahoo.com> + <1051621449.76105.9.camel@jester> +Comments: In-reply-to Rod Taylor + message dated "29 Apr 2003 09:04:09 -0400" +Date: Tue, 29 Apr 2003 10:18:19 -0400 +Message-ID: <26349.1051625899@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-31.0 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + QUOTED_EMAIL_TEXT,REFERENCES,REPLY_WITH_QUOTES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/244 +X-Sequence-Number: 1750 + +Rod Taylor writes: +>> What can I do to fix this -- is there something I am missing about +>> setting statistics or some configuration variable I can change? Any +>> insights would be greatly appreciated. Thank you, + +> You might try adjusting the random_page_cost down to something more +> appropriate for your hardware and situation. + +Also, is the table physically ordered by dsid? If so, is that condition +likely to persist? You may be looking at a test-condition artifact +here --- a poor estimate for an ordered table may not mean much when +you get to realistic database states. + +I assume you've done an ANALYZE of course --- what does the pg_stats row +for column dsid contain? + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 10:28:28 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 555E8475F0D + for ; + Tue, 29 Apr 2003 10:28:27 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 7975647631F + for ; + Tue, 29 Apr 2003 10:27:51 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TERtU6026414; + Tue, 29 Apr 2003 10:27:55 -0400 (EDT) +To: Rajesh Kumar Mallah +Cc: pgsql-performance@postgresql.org +Subject: Re: profiling plpgsql functions.. +In-reply-to: <200304291655.01035.mallah@trade-india.com> +References: <200304291655.01035.mallah@trade-india.com> +Comments: In-reply-to Rajesh Kumar Mallah + message dated "Tue, 29 Apr 2003 16:55:01 +0530" +Date: Tue, 29 Apr 2003 10:27:55 -0400 +Message-ID: <26413.1051626475@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-27.8 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,NO_DNS_FOR_FROM, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/245 +X-Sequence-Number: 1751 + +Rajesh Kumar Mallah writes: +> Is printing timeofday() at various points a good idea +> of profiling plpgsql functions? + +Sure. + +> also is anything wrong with following fragment ? +> RAISE INFO '' % , message here ... '' , timeofday() ; + +IIRC, RAISE is pretty slovenly implemented :-( ... it will only take +plain variable references as additional arguments. So you'll have to +do + + var := timeofday(); + RAISE INFO ''... '', var; + +I believe timeofday() produces TEXT, so declare the var that way. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 10:53:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id DDE7E475F00; Tue, 29 Apr 2003 10:53:47 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP + id D645F476262; Tue, 29 Apr 2003 10:53:11 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TErEU6026551; + Tue, 29 Apr 2003 10:53:14 -0400 (EDT) +To: "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" +Cc: pgsql-performance@postgresql.org, pgsql-sql@postgresql.org +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +In-reply-to: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> +References: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> +Comments: In-reply-to "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" + message dated "Tue, 29 Apr 2003 15:01:21 +0200" +Date: Tue, 29 Apr 2003 10:53:13 -0400 +Message-ID: <26550.1051627993@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-24.7 required=5.0 + tests=BAYES_01,IN_REP_TO,NO_DNS_FOR_FROM,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/246 +X-Sequence-Number: 1752 + +"=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" writes: +> A nasty query and its EXPLAINs are here. Read on at your own risk :) + +It's pretty much unreadable because of the way your mailer folded, +spindled, and mutilated the EXPLAIN output :-( + +Could you resend in a more legible format? Maybe append the explain +output as an attachment, if you can't get the mailer to leave its +formatting alone otherwise. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 11:40:08 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 84AFC475ADE + for ; + Tue, 29 Apr 2003 11:40:06 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 8659B475ADE + for ; + Tue, 29 Apr 2003 11:39:27 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2996181; Tue, 29 Apr 2003 08:38:54 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: "Robert John Shepherd" , + +Subject: Re: Best ODBC cursor and lock types for fastest reading? +Date: Tue, 29 Apr 2003 08:38:50 -0700 +User-Agent: KMail/1.4.3 +References: <001701c30e56$b0964400$f3b0313e@LAIKA> +In-Reply-To: <001701c30e56$b0964400$f3b0313e@LAIKA> +MIME-Version: 1.0 +Message-Id: <200304290838.50503.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-31.1 required=5.0 + tests=BAYES_01,IN_REP_TO,NO_DNS_FOR_FROM,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/247 +X-Sequence-Number: 1753 + +Robert, + +> The following options are defined in ADO with which I can create a +> recordset with: + +> Do any of these offer a performance gain over others? I used to use +> adLockReadOnly with MS-SQL which really sped things up but this doesn't +> seem to work at all under Postgresql and I've been using +> adLockOptimistic instead. + +All of the types you list were designed around the MS SQL/MSDE server=20 +architecture, and many do not apply to PostgreSQL (for example, Postgres do= +es=20 +not use read locks and does not support client-side keyset cursors as far a= +s=20 +I know). I wouldn't be surprised to find out that the pgODBC driver is=20 +ignoring most of these options as irrelevant -- you should contact the pgOD= +BC=20 +project to find out. + +Certainly I wouldn't expect any setting other than adLockPessimistic to hav= +e=20 +an effect on the speed at which you get rows from the server (Pessimistic= +=20 +would presumably declare "SELECT FOR UPDATE", which would be slower).=20=20= +=20 +However, one or more types might be faster on the client side than the=20 +others; I recommmend that you set up a test case and experiment. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 11:44:03 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CA6FE475CBC + for ; + Tue, 29 Apr 2003 11:44:02 -0400 (EDT) +Received: from mail.reviewer.co.uk (frodo.reviewer.co.uk [213.232.121.13]) + by postgresql.org (Postfix) with SMTP id AFAB247633C + for ; + Tue, 29 Apr 2003 11:43:22 -0400 (EDT) +Received: (qmail 27486 invoked from network); 29 Apr 2003 15:43:27 -0000 +Received: from unknown (HELO LAIKA) (62.49.176.243) + by mail.reviewer.co.uk with SMTP; 29 Apr 2003 15:43:27 -0000 +From: "Robert John Shepherd" +To: +Subject: Re: Best ODBC cursor and lock types for fastest reading? +Date: Tue, 29 Apr 2003 16:43:26 +0100 +Message-ID: <001a01c30e66$138f0920$f3b0313e@LAIKA> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="us-ascii" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook, Build 10.0.2627 +In-Reply-To: <200304290838.50503.josh@agliodbs.com> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +Importance: Normal +X-Spam-Status: No, hits=-8.2 required=5.0 + tests=BAYES_20,IN_REP_TO,NO_DNS_FOR_FROM,QUOTED_EMAIL_TEXT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/248 +X-Sequence-Number: 1754 + +> All of the types you list were designed around the MS SQL/MSDE server +> architecture, and many do not apply to PostgreSQL (for +> example, Postgres does not use read locks and does not support +> client-side keyset cursors as far as I know). + +Thanks, this backs up my feelings from some of my limited experiments +with them. + +I guess I need to keep trying to rewrite my queries to avoid nested +loops then, as this seems to be the main performance hit I get as all +use indexes properly. + + + +Yours Unwhettedly, +Robert John Shepherd. + +Editor +DVD REVIEWER +The UK's BIGGEST Online DVD Magazine +http://www.dvd.reviewer.co.uk + +For a copy of my Public PGP key, email: pgp@robertsworld.org.uk + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 11:49:43 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 84978476323 + for ; + Tue, 29 Apr 2003 11:49:40 -0400 (EDT) +Received: from rtlocal.trade-india.com (mail-relay.trade-india.com + [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id 9A3C5476333 + for ; + Tue, 29 Apr 2003 11:49:01 -0400 (EDT) +Received: (qmail 27824 invoked from network); 29 Apr 2003 15:49:42 -0000 +Received: from unknown (HELO www.trade-india.com) (unknown) + by unknown with SMTP; 29 Apr 2003 15:49:42 -0000 +Received: (qmail 25700 invoked by uid 99); 29 Apr 2003 15:48:57 -0000 +Received: from 219.65.230.214 (SquirrelMail authenticated user mallah) + by mail.trade-india.com with HTTP; + Tue, 29 Apr 2003 21:18:57 +0530 (IST) +Message-ID: <1057.219.65.230.214.1051631337.squirrel@mail.trade-india.com> +Date: Tue, 29 Apr 2003 21:18:57 +0530 (IST) +Subject: Re: Is 292 inserts/sec acceptable performance ? +From: +To: +In-Reply-To: <26231.1051624859@sss.pgh.pa.us> +References: <200304291231.09842.mallah@trade-india.com> + <26231.1051624859@sss.pgh.pa.us> +X-Priority: 3 +Importance: Normal +X-MSMail-Priority: Normal +Cc: +X-Mailer: SquirrelMail (version 1.2.6) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-13.1 required=5.0 + tests=BAYES_10,IN_REP_TO,MISSING_MIMEOLE,MISSING_OUTLOOK_NAME, + NO_DNS_FOR_FROM,NO_REAL_NAME,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/249 +X-Sequence-Number: 1755 + + + +it really takes that long :( +i can post it 2morrow only when i am office . + + +regds +mallah + +> Rajesh Kumar Mallah writes: +>> Hi Can anyone tell if the case below is an acceptable +>> performance ? +> +> Not with that info. Could we see EXPLAIN ANALYZE results for both the fa= +ster and slower cases? +> +> regards, tom lane + + + +----------------------------------------- +Get your free web based email at trade-india.com. + "India's Leading B2B eMarketplace.!" +http://www.trade-india.com/ + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 11:57:36 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 65F5A4763E6 + for ; + Tue, 29 Apr 2003 11:57:28 -0400 (EDT) +Received: from rtlocal.trade-india.com (mail-relay.trade-india.com + [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id 4DE734763B1 + for ; + Tue, 29 Apr 2003 11:56:12 -0400 (EDT) +Received: (qmail 28031 invoked from network); 29 Apr 2003 15:56:54 -0000 +Received: from unknown (HELO www.trade-india.com) (unknown) + by unknown with SMTP; 29 Apr 2003 15:56:54 -0000 +Received: (qmail 26117 invoked by uid 99); 29 Apr 2003 15:56:08 -0000 +Received: from 219.65.230.214 (SquirrelMail authenticated user mallah) + by mail.trade-india.com with HTTP; + Tue, 29 Apr 2003 21:26:08 +0530 (IST) +Message-ID: <1066.219.65.230.214.1051631768.squirrel@mail.trade-india.com> +Date: Tue, 29 Apr 2003 21:26:08 +0530 (IST) +Subject: Re: profiling plpgsql functions.. +From: +To: +In-Reply-To: <26413.1051626475@sss.pgh.pa.us> +References: <200304291655.01035.mallah@trade-india.com> + <26413.1051626475@sss.pgh.pa.us> +X-Priority: 3 +Importance: Normal +X-MSMail-Priority: Normal +Cc: +X-Mailer: SquirrelMail (version 1.2.6) +MIME-Version: 1.0 +Content-Type: text/plain; charset=iso-8859-1 +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-23.6 required=5.0 + tests=BAYES_01,IN_REP_TO,MISSING_MIMEOLE,MISSING_OUTLOOK_NAME, + NO_DNS_FOR_FROM,NO_REAL_NAME,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/250 +X-Sequence-Number: 1756 + + +Yep timeofday returns text , but is there anything else +that equivalant that can be differenced inside plpgsql +so that i can print the not of secs/millisecs connsumed? + +hmm shud i cast timeofday to timestamp and use timestamp +arithmatic ? + +regds +mallah. + +> Rajesh Kumar Mallah writes: +>> Is printing timeofday() at various points a good idea +>> of profiling plpgsql functions? +> +> Sure. +> +>> also is anything wrong with following fragment ? +>> RAISE INFO '' % , message here ... '' , timeofday() ; +> +> IIRC, RAISE is pretty slovenly implemented :-( ... it will only take plai= +n variable references +> as additional arguments. So you'll have to do +> +> var :=3D timeofday(); +> RAISE INFO ''... '', var; +> +> I believe timeofday() produces TEXT, so declare the var that way. +> +> regards, tom lane + + + +----------------------------------------- +Get your free web based email at trade-india.com. + "India's Leading B2B eMarketplace.!" +http://www.trade-india.com/ + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 12:02:09 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B248047635D + for ; + Tue, 29 Apr 2003 12:02:07 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 76AB7476372 + for ; + Tue, 29 Apr 2003 12:01:30 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TG1ZU6001911; + Tue, 29 Apr 2003 12:01:35 -0400 (EDT) +To: mallah@trade-india.com +Cc: pgsql-performance@postgresql.org +Subject: Re: profiling plpgsql functions.. +In-reply-to: <1066.219.65.230.214.1051631768.squirrel@mail.trade-india.com> +References: <200304291655.01035.mallah@trade-india.com> + <26413.1051626475@sss.pgh.pa.us> + <1066.219.65.230.214.1051631768.squirrel@mail.trade-india.com> +Comments: In-reply-to + message dated "Tue, 29 Apr 2003 21:26:08 +0530" +Date: Tue, 29 Apr 2003 12:01:35 -0400 +Message-ID: <1910.1051632095@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-14.8 required=5.0 + tests=BAYES_00,IN_REP_TO,NO_DNS_FOR_FROM,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/251 +X-Sequence-Number: 1757 + + writes: +> hmm shud i cast timeofday to timestamp and use timestamp +> arithmatic ? + +Yeah. It's only historical accident that it doesn't return timestamp... +(or better use timestamptz) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 12:04:35 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id BCCE7475F1B + for ; + Tue, 29 Apr 2003 12:04:34 -0400 (EDT) +Received: from mail.deltav.hu (mail.deltav.hu [213.163.0.192]) + by postgresql.org (Postfix) with ESMTP id 73DD4475F34 + for ; + Tue, 29 Apr 2003 12:03:58 -0400 (EDT) +Received: from fejleszt2 ([213.163.10.103]) by mail.deltav.hu + (Netscape Messaging Server 3.6) with SMTP id AAA2255 + for ; + Tue, 29 Apr 2003 18:03:55 +0200 +Message-ID: <011101c30e68$f056bdb0$0a03a8c0@fejleszt2> +From: "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" +To: +References: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> + <26550.1051627993@sss.pgh.pa.us> +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +Date: Tue, 29 Apr 2003 18:03:48 +0200 +MIME-Version: 1.0 +Content-Type: multipart/mixed; + boundary="----=_NextPart_000_010E_01C30E79.AEFC2E20" +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-11.5 required=5.0 + tests=BAYES_20,NO_DNS_FOR_FROM,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/252 +X-Sequence-Number: 1758 + +This is a multi-part message in MIME format. + +------=_NextPart_000_010E_01C30E79.AEFC2E20 +Content-Type: text/plain; + charset="iso-8859-2" +Content-Transfer-Encoding: 7bit + +Sure, thanks for your interest :) + +hope these help. + +G. +-- +while (!asleep()) sheep++; + +---------------------------- cut here ------------------------------ +----- Original Message ----- +From: "Tom Lane" +Sent: Tuesday, April 29, 2003 4:53 PM + + +> "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" writes: +> > A nasty query and its EXPLAINs are here. Read on at your own risk :) +> +> It's pretty much unreadable because of the way your mailer folded, +> spindled, and mutilated the EXPLAIN output :-( +> +> Could you resend in a more legible format? Maybe append the explain +> output as an attachment, if you can't get the mailer to leave its +> formatting alone otherwise. + +------=_NextPart_000_010E_01C30E79.AEFC2E20 +Content-Type: application/octet-stream; + name="szkb" +Content-Transfer-Encoding: quoted-printable +Content-Disposition: attachment; + filename="szkb" + +SELECT *, + kerekit_penznem (netto_ertek*(afa_szazalek/100), penznem)=20 + AS afa_ertek, + kerekit_penznem (netto_ertek*(1+afa_szazalek/100), penznem)=20 + AS brutto_ertek +FROM ( + SELECT szamla,=20 + kerekit_penznem( + elsodl_netto_ertek*COALESCE(deka,1)/COALESCE(dekb,1), penznem)=20 + AS netto_ertek, + konyvelesi_tetelcsoport, afa, afa_szazalek, penznem + FROM=20 + (SELECT szt.szamla,=20 + kerekit_penznem(sum(szt.netto_egysegar * szt.mennyiseg), penznem)=20 + AS elsodl_netto_ertek, + konyvelesi_tetelcsoport(szt.szamla, szt.tetelszam)=20 + AS konyvelesi_tetelcsoport, + szt.afa, afa.ertek AS afa_szazalek, + szamla.penznem AS sz_penznem, + szamla.teljesites AS sz_teljesites, + arf_a.deviza_kozeparfolyam as deka, + arf_b.deviza_kozeparfolyam as dekb, + foo_valuta AS penznem + FROM szamla_tetele szt=20 + LEFT JOIN szamla ON (szamla =3D szamla.az)=20 + LEFT JOIN afa ON (afa.az =3D szt.afa) + LEFT JOIN arfolyam arf_a=20 + ON (arf_a.ervenyes =3D=20 + (SELECT ervenyes FROM arfolyam + WHERE ervenyes<=3Dszamla.teljesites AND valuta =3D szamla.penznem + ORDER BY 1 DESC LIMIT 1) + AND szamla.penznem=3Darf_a.valuta) + JOIN=09 + (SELECT az AS foo_valuta FROM valuta) AS valuta ON (true) + LEFT JOIN arfolyam arf_b=20 + ON (arf_b.valuta=3Dfoo_valuta AND + arf_b.ervenyes =3D=20 + (SELECT ervenyes FROM arfolyam=20 + WHERE ervenyes<=3Dszamla.teljesites AND valuta =3D foo_valuta + ORDER BY 1 DESC LIMIT 1) + ) + WHERE (NOT szt.archiv) AND + (foo_valuta =3D 4 or arf_b.valuta notnull + ) + GROUP BY szt.szamla, konyvelesi_tetelcsoport, szt.afa,=20 + sz_penznem, sz_teljesites, afa.ertek,=20 + arf_a.deviza_kozeparfolyam, arf_b.deviza_kozeparfolyam,=20 + foo_valuta, penznem + ) foo=20 +) bar +WHERE szamla =3D 2380; + +------------------------------------------------------------------------- +---------------------------- 7.2.1 PLAN --------------------------------- +------------------------------------------------------------------------- + +NOTICE: QUERY PLAN: + +Subquery Scan foo (cost=3D488.97..490.94 rows=3D8 width=3D104) (actual tim= +e=3D94.77..109.10 rows=3D12 loops=3D1) +-> Aggregate (cost=3D488.97..490.94 rows=3D8 width=3D104) (actual time=3D= +89.29..92.05 rows=3D12 loops=3D1) + -> Group (cost=3D488.97..490.74 rows=3D79 width=3D104) (actual time= +=3D88.13..88.59 rows=3D12 loops=3D1) + -> Sort (cost=3D488.97..488.97 rows=3D79 width=3D104) (actual time=3D88.= +09..88.13 rows=3D12 loops=3D1) + -> Nested Loop (cost=3D1.05..486.50 rows=3D79 width=3D104) (actual t= +ime=3D28.23..86.20 rows=3D12 loops=3D1) + -> Nested Loop (cost=3D1.05..150.19 rows=3D79 width=3D84) (actual time= +=3D12.68..25.41 rows=3D12 loops=3D1) + -> Nested Loop (cost=3D1.05..135.52 rows=3D13 width=3D80) (actual t= +ime=3D12.60..24.80 rows=3D2 loops=3D1) + -> Hash Join (cost=3D1.05..79.59 rows=3D13 width=3D60) (actual time=3D= +0.55..0.80 rows=3D2 loops=3D1) + -> Nested Loop (cost=3D0.00..78.31 rows=3D13 width=3D46) (actual t= +ime=3D0.23..0.42 rows=3D2 loops=3D1) + -> Index Scan using szml_ttl_szml on szamla_tetele szt (cost=3D0.00..= +3.51 rows=3D13 width=3D34) (actual time=3D0.11..0.16 rows=3D2 loops=3D1) + -> Index Scan using szamla_az_key on szamla (cost=3D0.00..5.70 rows= +=3D1 width=3D12) (actual time=3D0.07..0.09 rows=3D1 loops=3D2) + -> Hash (cost=3D1.04..1.04 rows=3D4 width=3D14) (actual time=3D0.1= +4..0.14 rows=3D0 loops=3D1) + -> Seq Scan on afa (cost=3D0.00..1.04 rows=3D4 width=3D14) (actual ti= +me=3D0.08..0.11 rows=3D4 loops=3D1) + -> Index Scan using arfolyam_ervenyes on arfolyam arf_a (cost=3D0.00..= +3.63 rows=3D3 width=3D20) (actual time=3D0.01..0.01 rows=3D0 loops=3D2) + SubPlan + -> Limit (cost=3D0.00..0.17 rows=3D1 width=3D4) (actual time=3D11.= +92..11.92 rows=3D0 loops=3D2) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam (cost=3D0.= +00..13.30 rows=3D79 width=3D4) (actual time=3D11.90..11.90 rows=3D0 loops= +=3D2) + -> Limit (cost=3D0.00..0.17 rows=3D1 width=3D4) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam (cost=3D0.= +00..13.30 rows=3D79 width=3D4) + -> Seq Scan on valuta (cost=3D0.00..1.06 rows=3D6 width=3D4) (actua= +l time=3D0.02..0.11 rows=3D6 loops=3D2) + -> Index Scan using arfolyam_ervenyes on arfolyam arf_b (cost=3D0.00..3= +.63 rows=3D3 width=3D20) (actual time=3D0.04..0.10 rows=3D3 loops=3D12) + SubPlan + -> Limit (cost=3D0.00..0.17 rows=3D1 width=3D4) (actual time=3D4.35= +..4.39 rows=3D1 loops=3D12) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam (cost=3D0.0= +0..13.30 rows=3D79 width=3D4) (actual time=3D4.33..4.37 rows=3D2 loops=3D12) + -> Limit (cost=3D0.00..0.17 rows=3D1 width=3D4) + -> Index Scan Backward using arfolyam_ervenyes on arfolyam (cost=3D0.0= +0..13.30 rows=3D79 width=3D4) +Total runtime: 111.48 msec + +------------------------------------------------------------------------- +---------------------------- 7.3.2 PLAN --------------------------------- +------------------------------------------------------------------------- + = + QUERY PLAN=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20= +=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20 +---------------------------------------------------------------------------= +---------------------------------------------------------------------------= +------------------------------------------------------------------------- + Subquery Scan foo (cost=3D14542.01..15448.46 rows=3D3022 width=3D123) (ac= +tual time=3D2264.36..2282.17 rows=3D12 loops=3D1) + -> Aggregate (cost=3D14542.01..15448.46 rows=3D3022 width=3D123) (actu= +al time=3D2257.70..2261.08 rows=3D12 loops=3D1) + -> Group (cost=3D14542.01..15372.92 rows=3D30215 width=3D123) (a= +ctual time=3D2256.31..2256.84 rows=3D12 loops=3D1) + -> Sort (cost=3D14542.01..14617.55 rows=3D30215 width=3D12= +3) (actual time=3D2256.27..2256.31 rows=3D12 loops=3D1) + Sort Key: szt.szamla, konyvelesi_tetelcsoport(szt.szam= +la, szt.tetelszam), szt.afa, szamla.penznem, szamla.teljesites, afa.ertek, = +arf_a.deviza_kozeparfolyam, arf_b.deviza_kozeparfolyam, public.valuta.az + -> Merge Join (cost=3D4755.50..11038.79 rows=3D30215= + width=3D123) (actual time=3D80.88..2254.96 rows=3D12 loops=3D1) + Merge Cond: ("outer".az =3D "inner".valuta) + Join Filter: ("inner".ervenyes =3D (subplan)) + Filter: (("outer".az =3D 4) OR ("inner".valuta I= +S NOT NULL)) + -> Sort (cost=3D4676.19..4751.73 rows=3D30215 = +width=3D103) (actual time=3D56.41..56.44 rows=3D12 loops=3D1) + Sort Key: public.valuta.az + -> Nested Loop (cost=3D433.35..1375.92 r= +ows=3D30215 width=3D103) (actual time=3D55.78..56.18 rows=3D12 loops=3D1) + -> Merge Join (cost=3D433.35..469.= +47 rows=3D30 width=3D99) (actual time=3D55.68..55.72 rows=3D2 loops=3D1) + Merge Cond: ("outer".penznem = +=3D "inner".valuta) + Join Filter: ("inner".ervenyes= + =3D (subplan)) + -> Sort (cost=3D354.05..354.= +12 rows=3D30 width=3D79) (actual time=3D32.63..32.64 rows=3D2 loops=3D1) + Sort Key: szamla.penznem + -> Hash Join (cost=3D1= +21.67..353.30 rows=3D30 width=3D79) (actual time=3D32.37..32.49 rows=3D2 lo= +ops=3D1) + Hash Cond: ("outer= +".afa =3D "inner".az) + -> Merge Join (c= +ost=3D120.62..352.09 rows=3D30 width=3D58) (actual time=3D32.07..32.16 rows= +=3D2 loops=3D1) + Merge Cond: = +("outer".az =3D "inner".szamla) + -> Sort (c= +ost=3D120.62..123.85 rows=3D1291 width=3D12) (actual time=3D25.62..27.62 ro= +ws=3D1285 loops=3D1) + Sort K= +ey: szamla.az + -> Se= +q Scan on szamla (cost=3D0.00..53.91 rows=3D1291 width=3D12) (actual time= +=3D0.04..16.46 rows=3D1314 loops=3D1) + -> Index Sc= +an using szamla_tetele_pkey on szamla_tetele szt (cost=3D0.00..218.88 rows= +=3D30 width=3D46) (actual time=3D0.13..0.18 rows=3D2 loops=3D1) + Index = +Cond: (szamla =3D 2380) + Filter= +: (NOT archiv) + -> Hash (cost=3D= +1.04..1.04 rows=3D4 width=3D21) (actual time=3D0.10..0.10 rows=3D0 loops=3D= +1) + -> Seq Scan= + on afa (cost=3D0.00..1.04 rows=3D4 width=3D21) (actual time=3D0.04..0.07 = +rows=3D4 loops=3D1) + -> Sort (cost=3D79.30..82.19= + rows=3D1155 width=3D20) (actual time=3D22.93..22.93 rows=3D1 loops=3D1) + Sort Key: arf_a.valuta + -> Seq Scan on arfolyam= + arf_a (cost=3D0.00..20.55 rows=3D1155 width=3D20) (actual time=3D0.03..9.= +66 rows=3D1155 loops=3D1) + SubPlan + -> Limit (cost=3D0.00..0.1= +6 rows=3D1 width=3D4) (never executed) + -> Index Scan Backwar= +d using arfolyam_ervenyes on arfolyam (cost=3D0.00..12.17 rows=3D77 width= +=3D4) (never executed) + Index Cond: (erv= +enyes <=3D $0) + Filter: (valuta = +=3D $1) + -> Seq Scan on valuta (cost=3D0.00= +..20.00 rows=3D1000 width=3D4) (actual time=3D0.02..0.06 rows=3D6 loops=3D2) + -> Sort (cost=3D79.30..82.19 rows=3D1155 width= +=3D20) (actual time=3D21.98..27.54 rows=3D2309 loops=3D1) + Sort Key: arf_b.valuta + -> Seq Scan on arfolyam arf_b (cost=3D0.= +00..20.55 rows=3D1155 width=3D20) (actual time=3D0.03..9.89 rows=3D1155 loo= +ps=3D1) + SubPlan + -> Limit (cost=3D0.00..0.16 rows=3D1 width= +=3D4) (actual time=3D0.88..0.91 rows=3D1 loops=3D2310) + -> Index Scan Backward using arfolyam_e= +rvenyes on arfolyam (cost=3D0.00..12.17 rows=3D77 width=3D4) (actual time= +=3D0.87..0.90 rows=3D2 loops=3D2310) + Index Cond: (ervenyes <=3D $0) + Filter: (valuta =3D $2) + Total runtime: 2287.30 msec +(47 rows) + + +------=_NextPart_000_010E_01C30E79.AEFC2E20-- + + +From pgsql-performance-owner@postgresql.org Tue Apr 29 19:05:54 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9C2D7475F2C + for ; + Tue, 29 Apr 2003 19:05:53 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id F135B475CBC + for ; + Tue, 29 Apr 2003 19:05:52 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3TN5rU6018325; + Tue, 29 Apr 2003 19:05:53 -0400 (EDT) +To: "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" +Cc: pgsql-performance@postgresql.org +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +In-reply-to: <011101c30e68$f056bdb0$0a03a8c0@fejleszt2> +References: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> + <26550.1051627993@sss.pgh.pa.us> + <011101c30e68$f056bdb0$0a03a8c0@fejleszt2> +Comments: In-reply-to "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" + message dated "Tue, 29 Apr 2003 18:03:48 +0200" +Date: Tue, 29 Apr 2003 19:05:53 -0400 +Message-ID: <18324.1051657553@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-16.3 required=5.0 tests=BAYES_01,IN_REP_TO,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/253 +X-Sequence-Number: 1759 + +"=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" writes: +> ---------------------------- 7.2.1 PLAN --------------------------------- +> -> Seq Scan on valuta (cost=0.00..1.06 rows=6 width=4) (actual time=0.02..0.11 rows=6 loops=2) +> +> ---------------------------- 7.3.2 PLAN --------------------------------- +> -> Seq Scan on valuta (cost=0.00..20.00 rows=1000 width=4) (actual time=0.02..0.06 rows=6 loops=2) + +Ah, there's the problem. You never vacuumed or analyzed "valuta", so +the 7.3 planner didn't know it had only six rows, and chose a plan that +was more appropriate for a larger table. The thousand-row estimate is +the tipoff, because that's the default assumption when there are no +stats. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 02:04:26 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id EC7A8476300 + for ; + Wed, 30 Apr 2003 02:04:25 -0400 (EDT) +Received: from flake.decibel.org (flake.decibel.org [66.93.216.19]) + by postgresql.org (Postfix) with SMTP id 18C12475458 + for ; + Wed, 30 Apr 2003 02:04:25 -0400 (EDT) +Received: (qmail 86612 invoked by uid 1001); 30 Apr 2003 06:04:25 -0000 +Date: Wed, 30 Apr 2003 01:04:25 -0500 +From: "Jim C. Nasby" +To: pgsql-performance@postgresql.org +Subject: Why LIMIT after scanning the table? +Message-ID: <20030430010425.T66185@flake.decibel.org> +Reply-To: jim@nasby.net +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5.1i +X-Operating-System: FreeBSD 4.8-RELEASE i386 +X-Distributed: Join the Effort! http://www.distributed.net +X-Spam-Status: No, hits=-13.5 required=5.0 + tests=BAYES_01,SIGNATURE_SHORT_SPARSE,USER_AGENT_MUTT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/254 +X-Sequence-Number: 1760 + +I'm doing something where I just need to know if we have more than 100 +rows in a table. Not wanting to scan the whole table, I thought I'd get +cute... + +explain select count(*) + FROM (SELECT * FROM email_rank WHERE project_id = :ProjectID LIMIT 100) AS t1; + QUERY PLAN +------------------------------------------------------------------------------------- + Aggregate (cost=111.32..111.32 rows=1 width=48) + -> Subquery Scan t1 (cost=0.00..111.07 rows=100 width=48) + -> Limit (cost=0.00..111.07 rows=100 width=48) + -> Seq Scan on email_rank (cost=0.00..76017.40 rows=68439 width=48) + Filter: (project_id = 24) + +The idea is that the inner-most query would only read the first 100 rows +it finds, then stop. Instead, if explain is to be believed (and speed +testing seems to indicate it's accurate), we'll read the entire table, +*then* pick the first 100 rows. Why is that? + +FYI... + + Table "public.email_rank" + Column | Type | Modifiers +-----------------------+---------+-------------------- + project_id | integer | not null + id | integer | not null + first_date | date | not null + last_date | date | not null + day_rank | integer | not null default 0 + day_rank_previous | integer | not null default 0 + overall_rank | integer | not null default 0 + overall_rank_previous | integer | not null default 0 + work_today | bigint | not null default 0 + work_total | bigint | not null default 0 +Indexes: email_rank_pkey primary key btree (project_id, id), + email_rank__day_rank btree (project_id, day_rank), + email_rank__overall_rank btree (project_id, overall_rank) + +-- +Jim C. Nasby (aka Decibel!) jim@nasby.net +Member: Triangle Fraternity, Sports Car Club of America +Give your computer some brain candy! www.distributed.net Team #1828 + +Windows: "Where do you want to go today?" +Linux: "Where do you want to go tomorrow?" +FreeBSD: "Are you guys coming, or what?" + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 03:38:44 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 20CF6475458 + for ; + Wed, 30 Apr 2003 03:38:42 -0400 (EDT) +Received: from rtlocal.trade-india.com (mail-relay.trade-india.com + [203.196.129.235]) + by postgresql.org (Postfix) with SMTP id BF899474E42 + for ; + Wed, 30 Apr 2003 03:38:32 -0400 (EDT) +Received: (qmail 23007 invoked from network); 30 Apr 2003 07:39:16 -0000 +Received: from unknown (HELO system67.trade-india-local.com) (unknown) + by unknown with SMTP; 30 Apr 2003 07:39:16 -0000 +From: Rajesh Kumar Mallah +Organization: Infocom Network Limited +To: Tom Lane +Subject: Re: Is 292 inserts/sec acceptable performance ? +Date: Wed, 30 Apr 2003 13:09:53 +0530 +User-Agent: KMail/1.5 +Cc: pgsql-performance@postgresql.org +References: <200304291231.09842.mallah@trade-india.com> + <26231.1051624859@sss.pgh.pa.us> +In-Reply-To: <26231.1051624859@sss.pgh.pa.us> +MIME-Version: 1.0 +Content-Type: text/plain; + charset="utf-8" +Content-Transfer-Encoding: 7bit +Content-Disposition: inline +Message-Id: <200304301309.53150.mallah@trade-india.com> +X-Spam-Status: No, hits=-33.1 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES,SIGNATURE_SHORT_SPARSE, USER_AGENT + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/255 +X-Sequence-Number: 1761 + + +Ooops Sorry , + +Actually the query finished in approx 4 mins not 23 mins. +That performance must have been under some crazy circumstances. +So the insert Rate now is 1608 inserts/sec not 292 as stated +earlier. + +Here is the EXPLAIN ANALYZE anyway + + +tradein_clients=# begin work;EXPLAIN analyze INSERT INTO general.profile_master (email,country_code,city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexporter,ifservice,ifmanu,creation_date) SELECT email,country_code,city,title1,fname1,mname1,lname1,website,address,source,ifimporter,ifexporter,ifservice,ifmanu,creation_date from general.email_bank_import where not exists (select * from general.profile_master where email=general.email_bank_import.email) ; rollback; +BEGIN +Time: 993.07 ms ++---------------------------------------------------------------------------------------------------------------------------------------------------------+ +| QUERY PLAN | ++---------------------------------------------------------------------------------------------------------------------------------------------------------+ +| Hash Join (cost=8.07..2395887.30 rows=279296 width=129) (actual time=2.56..151083.30 rows=394646 loops=1) | +| Hash Cond: ("outer".country = "inner".name) | +| -> Seq Scan on email_bank a (cost=0.00..2390293.31 rows=279296 width=109) (actual time=0.36..41475.08 rows=394646 loops=1) | +| Filter: (NOT (subplan)) | +| SubPlan | +| -> Index Scan using profile_master_email on profile_master (cost=0.00..31.66 rows=7 width=678) (actual time=0.05..0.05 rows=0 loops=558731) | +| Index Cond: (email = $0) | +| -> Hash (cost=7.46..7.46 rows=246 width=20) (actual time=1.11..1.11 rows=0 loops=1) | +| -> Seq Scan on countries b (cost=0.00..7.46 rows=246 width=20) (actual time=0.06..0.73 rows=246 loops=1) | +| Total runtime: 196874.70 msec | ++---------------------------------------------------------------------------------------------------------------------------------------------------------+ +(10 rows) + +Time: 198905.62 ms +ROLLBACK +Time: 1481.41 ms + + +Regds +mallah. + + +On Tuesday 29 Apr 2003 7:30 pm, Tom Lane wrote: +> Rajesh Kumar Mallah writes: +> > Hi Can anyone tell if the case below is an acceptable +> > performance ? +> +> Not with that info. Could we see EXPLAIN ANALYZE results for both +> the faster and slower cases? +> +> regards, tom lane +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 6: Have you searched our list archives? +> +> http://archives.postgresql.org + +-- +Rajesh Kumar Mallah, +Project Manager (Development) +Infocom Network Limited, New Delhi +phone: +91(11)6152172 (221) (L) ,9811255597 (M) + +Visit http://www.trade-india.com , +India's Leading B2B eMarketplace. + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 07:00:49 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 68B18475458 + for ; + Wed, 30 Apr 2003 07:00:48 -0400 (EDT) +Received: from mail.deltav.hu (mail.deltav.hu [213.163.0.192]) + by postgresql.org (Postfix) with ESMTP id DC674474E42 + for ; + Wed, 30 Apr 2003 07:00:46 -0400 (EDT) +Received: from fejleszt2 ([213.163.10.103]) by mail.deltav.hu + (Netscape Messaging Server 3.6) with SMTP id AAA30CB + for ; + Wed, 30 Apr 2003 13:00:46 +0200 +Message-ID: <004401c30f07$c07f45e0$0a03a8c0@fejleszt2> +From: "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" +To: +References: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2> + <26550.1051627993@sss.pgh.pa.us> + <011101c30e68$f056bdb0$0a03a8c0@fejleszt2> + <18324.1051657553@sss.pgh.pa.us> +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +Date: Wed, 30 Apr 2003 13:00:40 +0200 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-2" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-19.1 required=5.0 + tests=BAYES_20,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/256 +X-Sequence-Number: 1762 + +----- Original Message ----- +From: "Tom Lane" +Sent: Wednesday, April 30, 2003 1:05 AM + + +> "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" writes: +> > ---------------------------- 7.2.1 +PLAN --------------------------------- +> > -> Seq Scan on valuta (cost=0.00..1.06 rows=6 width=4) (actual +time=0.02..0.11 rows=6 loops=2) +> > +> > ---------------------------- 7.3.2 +PLAN --------------------------------- +> > -> Seq Scan on valuta +(cost=0.00..20.00 rows=1000 width=4) (actual time=0.02..0.06 rows=6 loops=2) +> +> Ah, there's the problem. You never vacuumed or analyzed "valuta", so +> the 7.3 planner didn't know it had only six rows, and chose a plan that +> was more appropriate for a larger table. The thousand-row estimate is +> the tipoff, because that's the default assumption when there are no +> stats. +> +> regards, tom lane + +Thanks! + +VACUUM ANALYZE really worked and I learned something new. + +The strange part is, that I think I issued a "VACUUM ANALYZE;" (that should +do all the tables, right?) a couple of weeks before because of another +problem (it didn't help that time, tho) + +G. +-- +while (!asleep()) sheep++; + +---------------------------- cut here ------------------------------ + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 10:17:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D1DC54758E6 + for ; + Wed, 30 Apr 2003 10:17:23 -0400 (EDT) +Received: from email04.aon.at (WARSL401PIP5.highway.telekom.at [195.3.96.90]) + by postgresql.org (Postfix) with SMTP id D1204475458 + for ; + Wed, 30 Apr 2003 10:17:21 -0400 (EDT) +Received: (qmail 411140 invoked from network); 30 Apr 2003 14:15:16 -0000 +Received: from m154p015.dipool.highway.telekom.at (HELO cantor) ([62.46.9.47]) + (envelope-sender ) + by qmail4rs.highway.telekom.at (qmail-ldap-1.03) with SMTP + for ; 30 Apr 2003 14:15:16 -0000 +From: Manfred Koizar +To: jim@nasby.net +Cc: Tom Lane , pgsql-performance@postgresql.org +Subject: Re: More tablescanning fun +Date: Wed, 30 Apr 2003 16:14:46 +0200 +Message-ID: +References: <20030424183817.A66185@flake.decibel.org> + <3660.1051228710@sss.pgh.pa.us> + <20030424235924.B66185@flake.decibel.org> + <13549.1051248190@sss.pgh.pa.us> + <20030425093800.C66185@flake.decibel.org> +In-Reply-To: <20030425093800.C66185@flake.decibel.org> +X-Mailer: Forte Agent 1.8/32.548 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-32.2 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES,USER_AGENT_FORTE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/257 +X-Sequence-Number: 1763 + +On Fri, 25 Apr 2003 09:38:01 -0500, "Jim C. Nasby" +wrote: +>In this case, the interpolation can't be at fault, because correlation +>is 1 (unless the interpolation is backwards, but that doesn't appear to +>be the case). + +But your index has 3 columns which causes the index correlation to be +assumed as 1/3. So the interpolation uses 1/9 (correlation squared) +and you get a cost estimation that almost equals the upper bound. + +If you want to play around with other interpolation methods, you might +want to get this patch: http://www.pivot.at/pg/16-correlation-732.diff + +A short description of the GUC parameters introduced by this patch can +be found here: +http://archives.postgresql.org/pgsql-performance/2002-11/msg00256.php + +As a short term workaround for an unmodified Postgres installation, +you can create an index on email_contrib(project_id). + +Servus + Manfred + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 10:19:41 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id F0EA8475B85 + for ; + Wed, 30 Apr 2003 10:19:39 -0400 (EDT) +Received: from megazone.bigpanda.com (megazone.bigpanda.com [63.150.15.178]) + by postgresql.org (Postfix) with ESMTP id 99F5E475A45 + for ; + Wed, 30 Apr 2003 10:19:37 -0400 (EDT) +Received: by megazone.bigpanda.com (Postfix, from userid 1001) + id D8B9ED61D; Wed, 30 Apr 2003 07:19:41 -0700 (PDT) +Received: from localhost (localhost [127.0.0.1]) + by megazone.bigpanda.com (Postfix) with ESMTP + id CE6955C0A; Wed, 30 Apr 2003 07:19:41 -0700 (PDT) +Date: Wed, 30 Apr 2003 07:19:41 -0700 (PDT) +From: Stephan Szabo +To: "Jim C. Nasby" +Cc: +Subject: Re: Why LIMIT after scanning the table? +In-Reply-To: <20030430010425.T66185@flake.decibel.org> +Message-ID: <20030430071605.X81999-100000@megazone23.bigpanda.com> +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-26.0 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/258 +X-Sequence-Number: 1764 + +On Wed, 30 Apr 2003, Jim C. Nasby wrote: + +> I'm doing something where I just need to know if we have more than 100 +> rows in a table. Not wanting to scan the whole table, I thought I'd get +> cute... +> +> explain select count(*) +> FROM (SELECT * FROM email_rank WHERE project_id = :ProjectID LIMIT 100) AS t1; +> QUERY PLAN +> ------------------------------------------------------------------------------------- +> Aggregate (cost=111.32..111.32 rows=1 width=48) +> -> Subquery Scan t1 (cost=0.00..111.07 rows=100 width=48) +> -> Limit (cost=0.00..111.07 rows=100 width=48) +> -> Seq Scan on email_rank (cost=0.00..76017.40 rows=68439 width=48) +> Filter: (project_id = 24) +> +> The idea is that the inner-most query would only read the first 100 rows +> it finds, then stop. Instead, if explain is to be believed (and speed +> testing seems to indicate it's accurate), we'll read the entire table, +> *then* pick the first 100 rows. Why is that? + +I'd suggest looking at explain analyze rather than explain. In most cases +I've seen what it'll actually grab is limit+1 rows (I think cvs will only +grab limit) in the actual rows. It shows you the full count for the +sequence scan in explain, but notice that the limit cost is lower than +that of the sequence scan. + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 10:22:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C265147633A + for ; + Wed, 30 Apr 2003 10:22:23 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id AD81E4762FB + for ; + Wed, 30 Apr 2003 10:22:22 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3UEMPU6021976; + Wed, 30 Apr 2003 10:22:25 -0400 (EDT) +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: Why LIMIT after scanning the table? +In-reply-to: <20030430010425.T66185@flake.decibel.org> +References: <20030430010425.T66185@flake.decibel.org> +Comments: In-reply-to "Jim C. Nasby" + message dated "Wed, 30 Apr 2003 01:04:25 -0500" +Date: Wed, 30 Apr 2003 10:22:25 -0400 +Message-ID: <21975.1051712545@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-32.3 required=5.0 + tests=BAYES_00,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + REFERENCES,REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/259 +X-Sequence-Number: 1765 + +"Jim C. Nasby" writes: +> explain select count(*) +> FROM (SELECT * FROM email_rank WHERE project_id = :ProjectID LIMIT 100) AS t1; + +> The idea is that the inner-most query would only read the first 100 rows +> it finds, then stop. Instead, if explain is to be believed (and speed +> testing seems to indicate it's accurate), we'll read the entire table, +> *then* pick the first 100 rows. Why is that? + +You're misreading the EXPLAIN output. Try EXPLAIN ANALYZE to see how +many rows really get fetched. + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 10:40:08 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C48E54758E6 + for ; + Wed, 30 Apr 2003 10:40:06 -0400 (EDT) +Received: from mail.speakeasy.net (mail15.speakeasy.net [216.254.0.215]) + by postgresql.org (Postfix) with ESMTP id 6687C475458 + for ; + Wed, 30 Apr 2003 10:40:05 -0400 (EDT) +Received: (qmail 20616 invoked from network); 30 Apr 2003 14:39:28 -0000 +Received: from unknown (HELO pdarley) (kinesis@[216.254.16.50]) + (envelope-sender ) + by mail15.speakeasy.net (qmail-ldap-1.03) with SMTP + for ; 30 Apr 2003 14:39:28 -0000 +From: "Peter Darley" +To: +Subject: Query Plan far worse in 7.3.2 than 7.2.1 +Date: Wed, 30 Apr 2003 07:39:24 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: multipart/mixed; + boundary="----=_NextPart_000_000F_01C30EEB.9F203F60" +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) +Importance: Normal +In-Reply-To: <18324.1051657553@sss.pgh.pa.us> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-14.7 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/260 +X-Sequence-Number: 1766 + +This is a multi-part message in MIME format. + +------=_NextPart_000_000F_01C30EEB.9F203F60 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit + +Friends, + I've got a query that has stopped using an index scan between 7.2.1 or RH +7.1 and 7.3.2 or RH 8.0, and I can't figure out why. I've come up with a +replacement query which is a whole lot faster, but again, I can't tell why. + +The original query (condensed to remove the uninteresting bits) is: + +SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EXISTS (SELECT Foreign_Key +FROM Sample WHERE Foreign_Key='Quantum_' || Border_Shop_List.Assignment_ID +|| '_' || Assignment_Year || '_' || Evaluation_ID) + +This runs in 667055.79 msec + +The new one is: + +SELECT COUNT(*) FROM Border_Shop_List WHERE 'Quantum_' || +Border_Shop_List.Assignment_ID || '_' || Border_Shop_List.Assignment_Year || +'_' || Border_Shop_List.Evaluation_ID NOT IN (SELECT Foreign_Key FROM +Sample WHERE Foreign_Key IS NOT NULL) + +This runs in 16500.83 msec (~1/40th the time) + + Again, my immediate problem is solved, but I'm trying to understand why +there is such a speed difference. + + I've attached explains for the two querys in both versions. + + The schemas for the two databases are identical. If there's more info +people need, just let me know. + +Thanks, +Peter Darley + +------=_NextPart_000_000F_01C30EEB.9F203F60 +Content-Type: text/plain; + name="NewQuery.txt" +Content-Transfer-Encoding: quoted-printable +Content-Disposition: attachment; + filename="NewQuery.txt" + +SELECT COUNT(*) FROM Border_Shop_List WHERE 'Quantum_' || Border_Shop_List= +.Assignment_ID || '_' || Border_Shop_List.Assignment_Year || '_' || Border_= +Shop_List.Evaluation_ID NOT IN (SELECT Foreign_Key FROM Sample WHERE Forei= +gn_Key IS NOT NULL) + + + +7.3.2 +neo=3D# explain analyze SELECT COUNT(*) FROM Border_Shop_List WHERE 'Quant= +um_' || Border_Shop_List.Assignment_ID || '_' || Border_Shop_List.Assignmen= +t_Year || '_' || Border_Shop_List.Evaluation_ID NOT IN (SELECT Foreign_Key= + FROM Sample WHERE Foreign_Key IS NOT NULL); + QUERY PLAN +---------------------------------------------------------------------------= +--------------------------------------------------- + Aggregate (cost=3D2460448.75..2460448.75 rows=3D1 width=3D0) (actual time= +=3D16500.14..16500.14 rows=3D1 loops=3D1) + -> Seq Scan on border_shop_list (cost=3D0.00..2460447.50 rows=3D500 wi= +dth=3D0) (actual time=3D3245.59..16500.11 rows=3D3 loops=3D1) + Filter: (subplan) + SubPlan + -> Materialize (cost=3D2460.41..2460.41 rows=3D2741 width=3D34= +) (actual time=3D0.02..0.45 rows=3D1533 loops=3D3065) + -> Seq Scan on sample (cost=3D0.00..2460.41 rows=3D2741 = +width=3D34) (actual time=3D41.89..50.75 rows=3D3062 loops=3D1) + Filter: (foreign_key IS NOT NULL) + Total runtime: 16500.83 msec +(8 rows) + + + +7.2.1 +neo=3D# explain SELECT COUNT(*) FROM Border_Shop_List WHERE 'Quantum_' || = +Border_Shop_List.Assignment_ID || ' +_' || Border_Shop_List.Assignment_Year || '_' || Border_Shop_List.Evaluatio= +n_ID NOT IN (SELECT Foreign_Key +FROM Sample WHERE Foreign_Key IS NOT NULL); +NOTICE: QUERY PLAN: + +Aggregate (cost=3D11323743.75..11323743.75 rows=3D1 width=3D0) + -> Seq Scan on border_shop_list (cost=3D0.00..11323742.50 rows=3D500 wi= +dth=3D0) + SubPlan + -> Seq Scan on sample (cost=3D0.00..22647.41 rows=3D33457 width= +=3D34) + +EXPLAIN +------=_NextPart_000_000F_01C30EEB.9F203F60 +Content-Type: text/plain; + name="OldQuery.txt" +Content-Transfer-Encoding: quoted-printable +Content-Disposition: attachment; + filename="OldQuery.txt" + +SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EXISTS (SELECT Foreign_Key= + FROM Sample WHERE Foreign_Key=3D'Quantum_' || Border_Shop_List.Assignment_= +ID || '_' || Assignment_Year || '_' || Evaluation_ID) + + + +7.3.2 +neo=3D# explain analyze SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EX= +ISTS (SELECT Foreign_Key FROM Sample WHERE Foreign_Key=3D'Quantum_' || Bord= +er_Shop_List.Assignment_ID || '_' || Assignment_Year || '_' || Evaluation_I= +D); + QUERY PL= +AN +---------------------------------------------------------------------------= +--------------------------------------------------------------------- + Aggregate (cost=3D3959148.75..3959148.75 rows=3D1 width=3D0) (actual time= +=3D667055.64..667055.64 rows=3D1 loops=3D1) + -> Seq Scan on border_shop_list (cost=3D0.00..3959147.50 rows=3D500 wi= +dth=3D0) (actual time=3D110283.60..667055.60 rows=3D3 loops=3D1) + Filter: (NOT (subplan)) + SubPlan + -> Seq Scan on sample (cost=3D0.00..3959.13 rows=3D1 width=3D3= +4) (actual time=3D217.62..217.62 rows=3D1 loops=3D3065) + Filter: ((foreign_key)::text =3D ((((('Quantum_'::text || = +($0)::text) || '_'::text) || ($1)::text) || '_'::text) || ($2)::text)) + Total runtime: 667055.79 msec +(7 rows) + +7.2.1 +neo=3D# explain SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EXISTS (SE= +LECT Foreign_Key FROM Sample WHERE Foreign_Key=3D'Quantum_' || Border_Shop_= +List.Assignment_ID || '_' || Assignment_Year || '_' || Evaluation_ID); +NOTICE: QUERY PLAN: + +Aggregate (cost=3D5992.94..5992.94 rows=3D1 width=3D0) + -> Seq Scan on border_shop_list (cost=3D0.00..5991.69 rows=3D500 width= +=3D0) + SubPlan + -> Index Scan using sample_foreign_key on sample (cost=3D0.00..= +5.97 rows=3D1 width=3D34) + +EXPLAIN +------=_NextPart_000_000F_01C30EEB.9F203F60-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 10:54:56 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id AFCA74758E6 + for ; + Wed, 30 Apr 2003 10:54:55 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 8AB9C475458 + for ; + Wed, 30 Apr 2003 10:54:24 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.9/8.12.9) with ESMTP id h3UEsRU6022180; + Wed, 30 Apr 2003 10:54:28 -0400 (EDT) +To: "Peter Darley" +Cc: pgsql-performance@postgresql.org +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +In-reply-to: +References: +Comments: In-reply-to "Peter Darley" + message dated "Wed, 30 Apr 2003 07:39:24 -0700" +Date: Wed, 30 Apr 2003 10:54:27 -0400 +Message-ID: <22179.1051714467@sss.pgh.pa.us> +From: Tom Lane +X-Spam-Status: No, hits=-29.3 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,REFERENCES, + REPLY_WITH_QUOTES autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/261 +X-Sequence-Number: 1767 + +"Peter Darley" writes: +> SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EXISTS (SELECT Foreign_Key= +> FROM Sample WHERE Foreign_Key=3D'Quantum_' || Border_Shop_List.Assignment_= +> ID || '_' || Assignment_Year || '_' || Evaluation_ID) + +What's the datatype of Foreign_Key? + +I'm betting that it's varchar(n) or char(n). The result of the || +expression is text, and so the comparison can't use a varchar index +unless you explicitly cast it to varchar: + WHERE Foreign_Key = ('Quantum_' || ... || Evaluation_ID)::varchar + +I think 7.2 had some kluge in it that would allow a varchar index to be +used anyway, but we took out the kluge because it was semantically wrong +(it would also allow use of a char(n) index in place of a text +comparison, which alters the semantics...) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 11:14:26 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CDD35475458 + for ; + Wed, 30 Apr 2003 11:14:23 -0400 (EDT) +Received: from mail.speakeasy.net (mail15.speakeasy.net [216.254.0.215]) + by postgresql.org (Postfix) with ESMTP id 7F876475458 + for ; + Wed, 30 Apr 2003 11:13:52 -0400 (EDT) +Received: (qmail 22362 invoked from network); 30 Apr 2003 15:09:16 -0000 +Received: from unknown (HELO pdarley) (kinesis@[216.254.16.50]) + (envelope-sender ) + by mail15.speakeasy.net (qmail-ldap-1.03) with SMTP + for ; 30 Apr 2003 15:09:16 -0000 +From: "Peter Darley" +To: "Tom Lane" +Cc: +Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1 +Date: Wed, 30 Apr 2003 08:09:12 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) +Importance: Normal +In-Reply-To: <22179.1051714467@sss.pgh.pa.us> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-37.2 required=5.0 + tests=BAYES_10,EMAIL_ATTRIBUTION,IN_REP_TO,MSGID_GOOD_EXCHANGE, + ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,REPLY_WITH_QUOTES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/262 +X-Sequence-Number: 1768 + +Tom, + You hit the nail on the head, foreign_key is a varchar(250). I'll re-write +the queries with explicit casts. + I'm hesitant to say anything, because I'm really not in a position to +contribute, but... It seems like there are getting to be lots of typing +issues (this one, 2 isn't an int8, etc.) I think that people have said that +things are like this to support user defined data types. I would happily +get rid of user defined data types if it would help with the type conversion +issues. Just my 2c, for what it's worth. +Thanks, +Peter Darley + +-----Original Message----- +From: Tom Lane [mailto:tgl@sss.pgh.pa.us] +Sent: Wednesday, April 30, 2003 7:54 AM +To: Peter Darley +Cc: pgsql-performance@postgresql.org +Subject: Re: [PERFORM] Query Plan far worse in 7.3.2 than 7.2.1 + + +"Peter Darley" writes: +> SELECT COUNT(*) FROM Border_Shop_List WHERE NOT EXISTS (SELECT +Foreign_Key= +> FROM Sample WHERE Foreign_Key=3D'Quantum_' || +Border_Shop_List.Assignment_= +> ID || '_' || Assignment_Year || '_' || Evaluation_ID) + +What's the datatype of Foreign_Key? + +I'm betting that it's varchar(n) or char(n). The result of the || +expression is text, and so the comparison can't use a varchar index +unless you explicitly cast it to varchar: + WHERE Foreign_Key = ('Quantum_' || ... || Evaluation_ID)::varchar + +I think 7.2 had some kluge in it that would allow a varchar index to be +used anyway, but we took out the kluge because it was semantically wrong +(it would also allow use of a char(n) index in place of a text +comparison, which alters the semantics...) + + regards, tom lane + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 12:03:51 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 67A7B475A45; Wed, 30 Apr 2003 12:03:49 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id F00654758E6; Wed, 30 Apr 2003 12:03:47 -0400 (EDT) +Received: from [63.195.55.98] (HELO spooky) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2998610; Wed, 30 Apr 2003 09:03:52 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Organization: Aglio Database Solutions +To: Achilleus Mantzios , + pgsql-sql@postgresql.org +Subject: Re: [SQL] 7.3 analyze & vacuum analyze problem +Date: Wed, 30 Apr 2003 09:03:38 -0700 +User-Agent: KMail/1.4.3 +References: +In-Reply-To: +Cc: pgsql-performance@postgresql.org +MIME-Version: 1.0 +Message-Id: <200304300902.37985.josh@agliodbs.com> +Content-Transfer-Encoding: quoted-printable +X-Spam-Status: No, hits=-21.9 required=5.0 + tests=BAYES_10,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/263 +X-Sequence-Number: 1769 + +Achilleus, + +> i think i have an issue regarding the statistics that +> a) (plain) ANALYZE status and +> b) VACUUM ANALYZE status +> produce. + +It's perfectly normal for a query to run faster after a VACUUM ANALYZE than= +=20 +after an ANALYZE ... after all, you just vacuumed it, didn't you? + +If you're demonstrating some other kind of behavioural difference, then ple= +ase=20 +post the results of EXPLAIN ANALYZE for the two examples. + +Oh, and we should probably shift this discussion to the PGSQL-PERFORMANCE= +=20 +list. + +--=20 +Josh Berkus +Aglio Database Solutions +San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 12:22:14 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CF8BE4758E6 + for ; + Wed, 30 Apr 2003 12:22:13 -0400 (EDT) +Received: from beamish.nsd.ca (beamish.nsd.ca [205.150.156.194]) + by postgresql.org (Postfix) with ESMTP id EDEAB4758E6 + for ; + Wed, 30 Apr 2003 12:22:11 -0400 (EDT) +Received: (from smap@localhost) by beamish.nsd.ca (8.9.3/8.9.3) id MAA11666; + Wed, 30 Apr 2003 12:22:12 -0400 +X-Authentication-Warning: beamish.nsd.ca: smap set sender to + using -f +Received: from reddog.nsd.ca(192.168.101.30) by beamish.nsd.ca via smap + (V2.1/2.1+anti-relay+anti-spam) + id xma011664; Wed, 30 Apr 03 12:22:05 -0400 +Received: from nsd.ca (jllachan-linux.nsd.ca [192.168.101.148]) + by reddog.nsd.ca (8.8.7/8.8.7) with ESMTP id MAA08705; + Wed, 30 Apr 2003 12:15:58 -0400 +Message-ID: <3EAFF86F.910A76EF@nsd.ca> +Date: Wed, 30 Apr 2003 12:23:11 -0400 +From: Jean-Luc Lachance +X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.18-24.7.x i686) +X-Accept-Language: en +MIME-Version: 1.0 +To: jim@nasby.net +Cc: pgsql-performance@postgresql.org +Subject: Re: Why LIMIT after scanning the table? +References: <20030430010425.T66185@flake.decibel.org> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-30.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT,REFERENCES, + REPLY_WITH_QUOTES,X_AUTH_WARNING autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/265 +X-Sequence-Number: 1771 + +If you only what to know if there is more than 100 rows, why not do: + +if exists ( +SELECT 1 FROM email_rank WHERE project_id = :ProjectID OFFSET 100 LIMIT +1 +) + + +"Jim C. Nasby" wrote: +> +> I'm doing something where I just need to know if we have more than 100 +> rows in a table. Not wanting to scan the whole table, I thought I'd get +> cute... +> +> explain select count(*) +> FROM () AS t1; +> QUERY PLAN +> ------------------------------------------------------------------------------------- +> Aggregate (cost=111.32..111.32 rows=1 width=48) +> -> Subquery Scan t1 (cost=0.00..111.07 rows=100 width=48) +> -> Limit (cost=0.00..111.07 rows=100 width=48) +> -> Seq Scan on email_rank (cost=0.00..76017.40 rows=68439 width=48) +> Filter: (project_id = 24) +> +> The idea is that the inner-most query would only read the first 100 rows +> it finds, then stop. Instead, if explain is to be believed (and speed +> testing seems to indicate it's accurate), we'll read the entire table, +> *then* pick the first 100 rows. Why is that? +> +> FYI... +> +> Table "public.email_rank" +> Column | Type | Modifiers +> -----------------------+---------+-------------------- +> project_id | integer | not null +> id | integer | not null +> first_date | date | not null +> last_date | date | not null +> day_rank | integer | not null default 0 +> day_rank_previous | integer | not null default 0 +> overall_rank | integer | not null default 0 +> overall_rank_previous | integer | not null default 0 +> work_today | bigint | not null default 0 +> work_total | bigint | not null default 0 +> Indexes: email_rank_pkey primary key btree (project_id, id), +> email_rank__day_rank btree (project_id, day_rank), +> email_rank__overall_rank btree (project_id, overall_rank) +> +> -- +> Jim C. Nasby (aka Decibel!) jim@nasby.net +> Member: Triangle Fraternity, Sports Car Club of America +> Give your computer some brain candy! www.distributed.net Team #1828 +> +> Windows: "Where do you want to go today?" +> Linux: "Where do you want to go tomorrow?" +> FreeBSD: "Are you guys coming, or what?" +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 12:34:41 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id BA0D64762D7; Wed, 30 Apr 2003 12:34:40 -0400 (EDT) +Received: from MM01SNLNTO.son.sandia.gov (mm01snlnto.sandia.gov + [132.175.109.20]) by postgresql.org (Postfix) with ESMTP + id CBC00476182; Wed, 30 Apr 2003 12:34:39 -0400 (EDT) +Received: from 132.175.109.4 by MM01SNLNTO.son.sandia.gov with ESMTP ( + Tumbleweed MMS SMTP Relay 01 (MMS v5.5.0)); Wed, 30 Apr 2003 10:34:41 + -0600 +Received: from es08snlnt.sandia.gov (smtp-in.sandia.gov [134.253.130.11] + ) by mailgate2.sandia.gov (8.12.9/8.12.9) with ESMTP id h3UGYdbo013122; + Wed, 30 Apr 2003 10:34:39 -0600 (MDT) +Received: by es08snlnt.sandia.gov with Internet Mail Service ( + 5.5.2653.19) id <2AA2RKQC>; Wed, 30 Apr 2003 10:34:40 -0600 +Message-ID: +From: "Diehl, Jeffrey" +To: pgsql-sql@postgresql.org, pgsql-performance@postgresql.org +Subject: Like search performance. +Date: Wed, 30 Apr 2003 10:34:40 -0600 +MIME-Version: 1.0 +X-Mailer: Internet Mail Service (5.5.2653.19) +X-WSS-ID: 12B124AB212096-01-01 +Content-Type: text/plain; + charset=iso-8859-1 +Content-Transfer-Encoding: 7bit +X-Spam-Status: No, hits=-5.8 required=5.0 + tests=BAYES_10 + version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/266 +X-Sequence-Number: 1772 + +Hi all, + +I have a fairly large table with a char(20) field in it which I search on +quite a bit. The problem is that I tend to do a lot of +"...where field like '%-d%'" type searches on this field. + +Is there any to speed up this type of search? + +TIA, + +Mike Diehl. + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 13:26:37 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 4FA05475B85 + for ; + Wed, 30 Apr 2003 13:26:36 -0400 (EDT) +Received: from mail.deltav.hu (mail.deltav.hu [213.163.0.192]) + by postgresql.org (Postfix) with ESMTP id 37B68475C15 + for ; + Wed, 30 Apr 2003 13:26:35 -0400 (EDT) +Received: from fejleszt2 ([213.163.10.103]) by mail.deltav.hu + (Netscape Messaging Server 3.6) with SMTP id AAA5BD3 + for ; + Wed, 30 Apr 2003 18:59:53 +0200 +Message-ID: <02d601c30f39$eb1bb540$0a03a8c0@fejleszt2> +From: =?iso-8859-1?Q?SZUCS_G=E1bor?= +To: +References: +Subject: Re: Like search performance. +Date: Wed, 30 Apr 2003 18:59:52 +0200 +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 6.00.2800.1106 +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 +X-Spam-Status: No, hits=-19.1 required=5.0 + tests=BAYES_20,ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,REFERENCES + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/268 +X-Sequence-Number: 1774 + +I'm not an expert, but AFAIK locale and collation heavily affects LIKE, and +thus, IIRC there is no index search for like, maybe except the simplest +locales (maybe C and/or en_US?) + +But if you mean it... there is a nasty trick in the archives: + +http://archives.postgresql.org/pgsql-general/2002-08/msg00819.php + +Really, really nasty, but really nice at the same time. + +G. +-- +while (!asleep()) sheep++; + +---------------------------- cut here ------------------------------ +----- Original Message ----- +From: "Diehl, Jeffrey" +To: ; +Sent: Wednesday, April 30, 2003 6:34 PM +Subject: [PERFORM] Like search performance. + + +> Hi all, +> +> I have a fairly large table with a char(20) field in it which I search on +> quite a bit. The problem is that I tend to do a lot of +> "...where field like '%-d%'" type searches on this field. +> +> Is there any to speed up this type of search? +> +> TIA, +> +> Mike Diehl. +> +> +> ---------------------------(end of broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster +> + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 13:08:33 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 36B15475AE4 + for ; + Wed, 30 Apr 2003 13:08:32 -0400 (EDT) +Received: from c001.snv.cp.net (h007.c001.snv.cp.net [209.228.32.121]) + by postgresql.org (Postfix) with SMTP id 480C8475A45 + for ; + Wed, 30 Apr 2003 13:08:31 -0400 (EDT) +Received: (cpmta 21129 invoked from network); 30 Apr 2003 10:08:29 -0700 +Received: from 209.228.32.128 (HELO mail.dilger.cc.criticalpath.net) + by smtp.register-admin.com (209.228.32.121) with SMTP; + 30 Apr 2003 10:08:29 -0700 +X-Sent: 30 Apr 2003 17:08:29 GMT +Received: from [207.25.88.117] by mail.dilger.cc with HTTP; Wed, + 30 Apr 2003 10:08:28 -0700 (PDT) +Content-Type: text/plain; charset=iso-8859-1 +Content-Disposition: inline +Content-Transfer-Encoding: 7bit +MIME-Version: 1.0 +To: jdiehl@sandia.gov +Cc: pgsql-sql@postgresql.org, pgsql-performance@postgresql.org +From: "Nikolaus Dilger" +Subject: Re: Like search performance. +X-Sent-From: nikolaus@dilger.cc +Date: Wed, 30 Apr 2003 10:08:28 -0700 (PDT) +X-Mailer: Web Mail 5.3.1-0_sol28 +Message-Id: <20030430100829.9198.h014.c001.wm@mail.dilger.cc.criticalpath.net> +X-Spam-Status: No, hits=-13.7 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,QUOTE_TWICE_1 + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/267 +X-Sequence-Number: 1773 + +Jeffrey, + +The best thing you can do is to have the wildcard % as +late as possible in your search condition. +So do like 'd%' instead of like '%d%' if you can. + +Regards, +Nikolaus + + +On Wed, 30 Apr 2003 10:34:40 -0600, "Diehl, Jeffrey" +wrote: + +> +> Hi all, +> +> I have a fairly large table with a char(20) field in +it +> which I search on +> quite a bit. The problem is that I tend to do a lot +of +> "...where field like '%-d%'" type searches on this +> field. +> +> Is there any to speed up this type of search? +> +> TIA, +> +> Mike Diehl. +> +> +> ---------------------------(end of +> broadcast)--------------------------- +> TIP 4: Don't 'kill -9' the postmaster + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 13:33:48 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id B69BB475AE4; Wed, 30 Apr 2003 13:33:47 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP + id E6B79475A45; Wed, 30 Apr 2003 13:33:46 -0400 (EDT) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2998830; Wed, 30 Apr 2003 10:33:45 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: "Diehl, Jeffrey" , pgsql-sql@postgresql.org, + pgsql-performance@postgresql.org +Subject: Re: Like search performance. +Date: Wed, 30 Apr 2003 10:33:17 -0700 +User-Agent: KMail/1.4.3 +References: +In-Reply-To: +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304301033.18357.josh@agliodbs.com> +X-Spam-Status: No, hits=-22.7 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/269 +X-Sequence-Number: 1775 + +Mike, + +> I have a fairly large table with a char(20) field in it which I search on +> quite a bit. The problem is that I tend to do a lot of=20 +> "...where field like '%-d%'" type searches on this field. +>=20 +> Is there any to speed up this type of search? + +Yes. See the tsearch module in /contrib in your postgresql source. + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 14:48:53 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3A325475C15 + for ; + Wed, 30 Apr 2003 14:48:53 -0400 (EDT) +Received: from davinci.ethosmedia.com (unknown [209.10.40.251]) + by postgresql.org (Postfix) with ESMTP id 3F38D475A45 + for ; + Wed, 30 Apr 2003 14:48:46 -0400 (EDT) +Received: from [66.219.92.2] (HELO temoku) + by davinci.ethosmedia.com (CommuniGate Pro SMTP 4.0.2) + with ESMTP id 2999138; Wed, 30 Apr 2003 11:48:45 -0700 +Content-Type: text/plain; + charset="iso-8859-1" +From: Josh Berkus +Reply-To: josh@agliodbs.com +Organization: Aglio Database Solutions +To: Achilleus Mantzios +Subject: Re: [SQL] 7.3 analyze & vacuum analyze problem +Date: Wed, 30 Apr 2003 11:48:18 -0700 +User-Agent: KMail/1.4.3 +Cc: +References: +In-Reply-To: +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200304301148.18322.josh@agliodbs.com> +X-Spam-Status: No, hits=-22.7 required=5.0 + tests=BAYES_01,IN_REP_TO,REFERENCES,USER_AGENT_KMAIL + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/270 +X-Sequence-Number: 1776 + +Achilleus, + +> I am afraid it is not so simple. +> What i (unsuccessfully) implied is that=20 +> dynacom=3D# VACUUM ANALYZE status ; +> VACUUM +> dynacom=3D# ANALYZE status ; +> ANALYZE +> dynacom=3D# + +You're right, that is mysterious. If you don't get a response from one of= +=20 +the major developers on this forum, I suggest that you post those EXPLAIN= +=20 +results to PGSQL-BUGS. + +--=20 +-Josh Berkus + Aglio Database Solutions + San Francisco + + +From pgsql-sql-owner@postgresql.org Wed Apr 30 11:55:44 2003 +X-Original-To: pgsql-sql@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C454E475CE5 + for ; Wed, 30 Apr 2003 11:55:39 -0400 (EDT) +Received: from matrix.gatewaynet.com (unknown [217.19.69.50]) + by postgresql.org (Postfix) with ESMTP id 6AB71475A45 + for ; Wed, 30 Apr 2003 11:55:33 -0400 (EDT) +Received: from matrix.gatewaynet.com (localhost [127.0.0.1]) + by matrix.gatewaynet.com (8.12.5/8.12.5) with ESMTP id h3UKvW1s009311 + for ; Wed, 30 Apr 2003 18:57:32 -0200 +Received: from localhost (achill@localhost) + by matrix.gatewaynet.com (8.12.5/8.12.5/Submit) with ESMTP id + h3UKvVwK009307 + for ; Wed, 30 Apr 2003 18:57:32 -0200 +Date: Wed, 30 Apr 2003 18:57:31 -0200 (GMT+2) +From: Achilleus Mantzios +To: pgsql-sql@postgresql.org +Subject: 7.3 analyze & vacuum analyze problem +In-Reply-To: <3E92E3B1.7070405@eselx.ipl.pt> +Message-ID: +MIME-Version: 1.0 +Content-Type: MULTIPART/MIXED; + BOUNDARY="333001285-2121937442-1051736251=:8921" +X-Spam-Status: No, hits=-15.5 required=5.0 + tests=BAYES_01,IN_REP_TO,USER_AGENT_PINE + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/440 +X-Sequence-Number: 13141 + + This message is in MIME format. The first part should be readable text, + while the remaining parts are likely unreadable without MIME-aware tools. + Send mail to mime@docserver.cac.washington.edu for more info. + +--333001285-2121937442-1051736251=:8921 +Content-Type: TEXT/PLAIN; charset=US-ASCII + + +Hi, +i think i have an issue regarding the statistics that +a) (plain) ANALYZE status and +b) VACUUM ANALYZE status +produce. + +I have a table status: +dynacom=# \d status + Table "public.status" + Column | Type | Modifiers + +-------------+--------------------------+--------------------------------------------------- + id | integer | not null default +nextval('"status_id_seq"'::text) + checkdate | timestamp with time zone | + assettable | character varying(50) | + assetidval | integer | + appname | character varying(100) | + apptblname | character varying(50) | + apptblidval | integer | + colname | character varying(50) | + colval | double precision | + status | character varying(5) | + isvalid | boolean | + username | character varying(50) | +Indexes: status_id_key unique btree (id), + status_all btree (assettable, assetidval, appname, apptblname, +status, isvalid), + status_all_wo_astidval btree (assettable, appname, apptblname, +status, isvalid), + status_appname btree (appname), + status_apptblidval btree (apptblidval), + status_apptblname btree (apptblname), + status_assetidval btree (assetidval), + status_assettable btree (assettable), + status_checkdate btree (checkdate), + status_colname btree (colname), + status_isvalid btree (isvalid), + status_status btree (status) + +dynacom=# +dynacom=# SELECT count(*) from status ; + count +------- + 33565 +(1 row) + +dynacom=# + +I very often perform queries of the form: + + select count(*) from status where assettable='vessels' and +appname='ISM PMS' and apptblname='items' and status='warn' +and isvalid and assetidval=; + +Altho i dont understand exactly why the stats created by +VACUUM ANALYZE are more accurate (meaning producing faster plans) +than the ones created by +plain ANALYZE, (altho for some attributes they are false for sure) +the performance is much much better when +VACUUM ANALYZE is run than plain ANALYZE. + +In the former case, some times the status_all index is used, +and sometimes (when the selectivity is small) +a sequential scan is performed. + +In the latter case, no index is ever used even +for crazy statements (assetidval is always >0) like: + +select count(*) from status where assettable='vessels' and +appname='ISM PMS' and apptblname='items' and status='warn' +and isvalid and assetidval=-10000000; + +I attach the statistics of either case. + +My app just performs the above query for most of the assetidval values +(And for all most popular assetidval values) +So the elapsed time of the app i think is a good +measure of the overall performance of these queries. + +In the "VACUUM ANALYZE" case it takes 1.2 - 1.5 secs, while +in the "ANALYZE" case it takes >=3+ + +-- +================================================================== +Achilleus Mantzios +S/W Engineer +IT dept +Dynacom Tankers Mngmt +Nikis 4, Glyfada +Athens 16610 +Greece +tel: +30-210-8981112 +fax: +30-210-8981877 +email: achill@matrix.gatewaynet.com + mantzios@softlab.ece.ntua.gr + +--333001285-2121937442-1051736251=:8921 +Content-Type: TEXT/PLAIN; charset=US-ASCII; name=2see-VACUUM_ANALYZE +Content-Transfer-Encoding: BASE64 +Content-ID: +Content-Description: +Content-Disposition: attachment; filename=2see-VACUUM_ANALYZE + +ICAgYXR0bmFtZSAgIHwgbnVsbF9mcmFjIHwgYXZnX3dpZHRoIHwgbl9kaXN0 +aW5jdCB8ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICBtb3N0 +X2NvbW1vbl92YWxzICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg +ICB8ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg +IG1vc3RfY29tbW9uX2ZyZXFzICAgICAgICAgICAgICAgICAgICAgICAgICAg +ICAgICAgICAgICAgICAgIHwgICAgICAgICAgICAgICAgICAgICAgICAgICAg +ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg 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+ICAgICAgICAgICB8ICAgIDAuODE3MDk2DQooMTIgcm93cykNCg0K + +--333001285-2121937442-1051736251=:8921-- + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 12:11:47 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id E3329476083; Wed, 30 Apr 2003 12:11:45 -0400 (EDT) +Received: from matrix.gatewaynet.com (unknown [217.19.69.50]) + by postgresql.org (Postfix) with ESMTP + id 1F2EE475F2C; Wed, 30 Apr 2003 12:11:44 -0400 (EDT) +Received: from matrix.gatewaynet.com (localhost [127.0.0.1]) + by matrix.gatewaynet.com (8.12.5/8.12.5) with ESMTP id h3ULDe1s009392; + Wed, 30 Apr 2003 19:13:40 -0200 +Received: from localhost (achill@localhost) + by matrix.gatewaynet.com (8.12.5/8.12.5/Submit) with ESMTP id + h3ULDe50009388; Wed, 30 Apr 2003 19:13:40 -0200 +Date: Wed, 30 Apr 2003 19:13:40 -0200 (GMT+2) +From: Achilleus Mantzios +To: Josh Berkus +Cc: pgsql-sql@postgresql.org, +Subject: Re: [SQL] 7.3 analyze & vacuum analyze problem +In-Reply-To: <200304300902.37985.josh@agliodbs.com> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Spam-Status: No, hits=-38.6 required=5.0 + tests=BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, + QUOTE_TWICE_1,REPLY_WITH_QUOTES,SIGNATURE_LONG_DENSE, + USER_AGENT_PINE autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/264 +X-Sequence-Number: 1770 + +On Wed, 30 Apr 2003, Josh Berkus wrote: + +> Achilleus, +> +> > i think i have an issue regarding the statistics that +> > a) (plain) ANALYZE status and +> > b) VACUUM ANALYZE status +> > produce. +> +> It's perfectly normal for a query to run faster after a VACUUM ANALYZE than +> after an ANALYZE ... after all, you just vacuumed it, didn't you? + +I am afraid it is not so simple. +What i (unsuccessfully) implied is that +dynacom=# VACUUM ANALYZE status ; +VACUUM +dynacom=# ANALYZE status ; +ANALYZE +dynacom=# + +is enuf to damage the performance. + +> +> If you're demonstrating some other kind of behavioural difference, then please +> post the results of EXPLAIN ANALYZE for the two examples. +> +dynacom=# ANALYZE status ; +ANALYZE +dynacom=# EXPLAIN ANALYZE select count(*) from status where +assettable='vessels' and appname='ISM PMS' and apptblname='items' and +status='warn' and isvalid and assetidval=49; + + QUERY PLAN + +------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Aggregate (cost=4309.53..4309.53 rows=1 width=0) (actual +time=242.60..242.60 rows=1 loops=1) + -> Seq Scan on status (cost=0.00..4306.08 rows=1378 width=0) (actual +time=15.75..242.51 rows=50 loops=1) + Filter: ((assettable = 'vessels'::character varying) AND (appname += 'ISM PMS'::character varying) AND (apptblname = 'items'::character +varying) AND (status = 'warn'::character varying) AND isvalid AND +(assetidval = 49)) + Total runtime: 242.74 msec +(4 rows) + +dynacom=# +dynacom=# VACUUM ANALYZE status ; +VACUUM +dynacom=# EXPLAIN ANALYZE select count(*) from status where +assettable='vessels' and appname='ISM PMS' and apptblname='items' and +status='warn' and isvalid and assetidval=49; + + QUERY PLAN + +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Aggregate (cost=2274.90..2274.90 rows=1 width=0) (actual time=8.89..8.89 +rows=1 loops=1) -> Index Scan using status_all on status +(cost=0.00..2274.34 rows=223 width=0) (actual time=8.31..8.83 rows=50 +loops=1) + Index Cond: ((assettable = 'vessels'::character varying) AND +(assetidval = 49) AND (appname = 'ISM PMS'::character varying) AND +(apptblname = 'items'::character varying) AND (status = 'warn'::character +varying)) + Filter: isvalid + Total runtime: 8.98 msec +(5 rows) + +dynacom=# + +> Oh, and we should probably shift this discussion to the PGSQL-PERFORMANCE +> list. +> + +OK. + +> + +-- +================================================================== +Achilleus Mantzios +S/W Engineer +IT dept +Dynacom Tankers Mngmt +Nikis 4, Glyfada +Athens 16610 +Greece +tel: +30-210-8981112 +fax: +30-210-8981877 +email: achill@matrix.gatewaynet.com + mantzios@softlab.ece.ntua.gr + + +From pgsql-performance-owner@postgresql.org Wed Apr 30 18:25:25 2003 +X-Original-To: pgsql-performance@postgresql.org +Received: from spampd.localdomain (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 47083476182 + for ; + Wed, 30 Apr 2003 18:25:24 -0400 (EDT) +Received: from torque.intervideoinc.com (mail.intervideo.com + [206.112.112.151]) + by postgresql.org (Postfix) with ESMTP id 69AB34760E3 + for ; + Wed, 30 Apr 2003 18:25:23 -0400 (EDT) +Received: from ronpc [63.68.5.2] by torque.intervideoinc.com + (SMTPD32-5.05) id A22C46460060; Wed, 30 Apr 2003 15:46:04 -0700 +From: "Ron Mayer" +To: , + "Achilleus Mantzios" +Cc: +Subject: Re: [SQL] 7.3 analyze & vacuum analyze problem +Date: Wed, 30 Apr 2003 15:16:58 -0700 +Message-ID: +MIME-Version: 1.0 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Priority: 3 (Normal) +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) +Importance: Normal +In-Reply-To: <200304301148.18322.josh@agliodbs.com> +X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2727.1300 +X-Spam-Status: No, hits=-14.3 required=5.0 + tests=BAYES_10,IN_REP_TO,MSGID_GOOD_EXCHANGE,SMTPD_IN_RCVD + autolearn=ham version=2.50 +X-Spam-Level: +X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) +X-Archive-Number: 200304/271 +X-Sequence-Number: 1777 + + +Josh wrote... +> Achilleus, +> +> > I am afraid it is not so simple. +> > What i (unsuccessfully) implied is that +> > dynacom=# VACUUM ANALYZE status ; +> > VACUUM +> > dynacom=# ANALYZE status ; +> > ANALYZE +> > dynacom=# +> > +> > [is enuf to damage the performance.] +> +> You're right, that is mysterious. If you don't get a response from one of +> the major developers on this forum, I suggest that you post those EXPLAIN +> results to PGSQL-BUGS. + +I had the same problem a while back. + +http://archives.postgresql.org/pgsql-bugs/2002-08/msg00015.php +http://archives.postgresql.org/pgsql-bugs/2002-08/msg00018.php +http://archives.postgresql.org/pgsql-bugs/2002-08/msg00018.php + +Short summary: Later in the thread Tom explained my problem as free +space not being evenly distributed across the table so ANALYZE's +sampling gave skewed results. In my case, "pgstatuple" was a +good tool for diagnosing the problem, "vacuum full" fixed my table +and a much larger fsm_* would have probably prevented it. + +