diff --git "a/pgsql-performance.200209" "b/pgsql-performance.200209" new file mode 100644--- /dev/null +++ "b/pgsql-performance.200209" @@ -0,0 +1,4129 @@ +From pgsql-performance-owner@postgresql.org Tue Sep 10 02:40:47 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 6DA40475C8B + for ; + Tue, 10 Sep 2002 02:40:46 -0400 (EDT) +Received: from ns1.officenet.no (ns1.officenet.no [193.212.174.3]) + by postgresql.org (Postfix) with ESMTP id B8F35475C45 + for ; + Tue, 10 Sep 2002 02:40:45 -0400 (EDT) +Received: from [193.212.174.117] (helo=jeb.officenet.no) + by ns1.officenet.no with esmtp (Exim 3.36 #3) id 17oehY-0000Yq-00 + for pgsql-performance@postgresql.org; Tue, 10 Sep 2002 08:40:44 +0200 +Content-Type: text/plain; + charset="us-ascii" +From: Andreas Joseph Krogh +Organization: OfficeNet AS +To: pgsql-performance@postgresql.org +Subject: subscribe +Date: Tue, 10 Sep 2002 08:40:44 +0200 +User-Agent: KMail/1.4.3 +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200209100840.44400.andreak@officenet.no> +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1 +X-Sequence-Number: 1 + + + + +From pgsql-performance-owner@postgresql.org Tue Sep 10 08:31:09 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7769A4761AF + for ; + Tue, 10 Sep 2002 08:31:08 -0400 (EDT) +Received: from dune.aardvarkmedia.co.uk (unknown [195.224.39.132]) + by postgresql.org (Postfix) with ESMTP id 97E5B476092 + for ; + Tue, 10 Sep 2002 08:31:07 -0400 (EDT) +Received: from [192.168.168.13] (helo=Gavin) + by dune.aardvarkmedia.co.uk with smtp (Exim 3.33 #1) + id 17okAe-0006ek-00 + for pgsql-performance@postgresql.org; Tue, 10 Sep 2002 13:31:08 +0100 +From: "Gavin Love" +To: +Subject: subscribe +Date: Tue, 10 Sep 2002 13:31:10 +0100 +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 V5.50.4522.1200 +Importance: Normal +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/2 +X-Sequence-Number: 2 + +subscribe + +From pgsql-performance-owner@postgresql.org Tue Sep 10 11:20:22 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 8FE8D47671C + for ; + Tue, 10 Sep 2002 11:20:19 -0400 (EDT) +Received: from mail.arcamax.com (mail.arcamax.com [209.96.210.69]) + by postgresql.org (Postfix) with SMTP id 02ABE476711 + for ; + Tue, 10 Sep 2002 11:20:18 -0400 (EDT) +Received: (qmail 11924 invoked by uid 526); 10 Sep 2002 15:20:20 -0000 +Received: from unknown (HELO arcamax.com) (192.168.0.32) + by 0 with SMTP; 10 Sep 2002 15:20:20 -0000 +Message-ID: <3D7E0DB7.9040108@arcamax.com> +Date: Tue, 10 Sep 2002 11:20:23 -0400 +From: Bryan White +User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; + rv:1.1) Gecko/20020826 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: pgsql-performance@postgresql.org +Subject: subscribe +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS perl-11 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/4 +X-Sequence-Number: 4 + + + +From pgsql-performance-owner@postgresql.org Tue Sep 10 12:02:04 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id B3FB6476534 + for ; + Tue, 10 Sep 2002 12:02:00 -0400 (EDT) +Received: from h009.c021.snv.cp.net (h009.c021.snv.cp.net [209.228.35.179]) + by postgresql.org (Postfix) with ESMTP id 2E6BC476515 + for ; + Tue, 10 Sep 2002 12:02:00 -0400 (EDT) +Received: from vengabox.candlefire.org (12.255.22.43) by h009.c021.snv.cp.net + (5.6.0.25) (authenticated as jlarson@candlefire.org) + id 3D1DA655000EB024 for pgsql-performance@postgresql.org; + Tue, 10 Sep 2002 09:02:05 -0700 +Date: Tue, 10 Sep 2002 10:07:06 -0600 +From: Jason k Larson +X-Mailer: The Bat! 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charset="iso-8859-1" +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/8 +X-Sequence-Number: 8 + +subscribe + +From pgsql-performance-owner@postgresql.org Wed Sep 11 07:09:17 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 62E4A4759F5 + for ; + Wed, 11 Sep 2002 07:09:16 -0400 (EDT) +Received: from out-mta3.plasa.com (out-mta2.plasa.com [202.134.0.198]) + by postgresql.org (Postfix) with ESMTP id B79CA476506 + for ; + Wed, 11 Sep 2002 07:09:13 -0400 (EDT) +Received: from [61.5.9.21] (helo=portab) + by out-mta3.plasa.com with smtp (Exim 4.04) id 17p5Mv-000nOk-00 + for pgsql-performance@postgresql.org; Wed, 11 Sep 2002 18:09:13 +0700 +Message-ID: <006e01c25984$0e0292c0$1509053d@portab> +From: "kopra" +To: +Subject: subscribe +Date: Wed, 11 Sep 2002 18:05:35 +0700 +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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/9 +X-Sequence-Number: 9 + +subscribe + + +------------------------------------------------------------------------------ + > Khusus Pelanggan Telepon DIVRE 2, Tekan 166 untuk mendengarkan pesan Anda + ------------------------------------------------------------------------------ + +From pgsql-performance-owner@postgresql.org Fri Sep 13 20:16:03 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id D4C364760BC + for ; + Fri, 13 Sep 2002 20:16:00 -0400 (EDT) +Received: from smtp3.ihug.com.au (smtp3.ihug.com.au [203.109.250.76]) + by postgresql.org (Postfix) with ESMTP id EBF80475E22 + for ; + Fri, 13 Sep 2002 20:15:58 -0400 (EDT) +Received: from p568-tnt1.mel.ihug.com.au (postgresql.org) [203.173.162.60] + by smtp3.ihug.com.au with esmtp (Exim 3.22 #1 (Debian)) + id 17q0bQ-00077B-00; Sat, 14 Sep 2002 10:16:00 +1000 +Message-ID: <3D827FBF.4F137D2E@postgresql.org> +Date: Sat, 14 Sep 2002 10:15:59 +1000 +From: Justin Clift +X-Mailer: Mozilla 4.79 [en] (WinNT; U) +X-Accept-Language: en +MIME-Version: 1.0 +To: PostgreSQL Performance Mailing List +Subject: Anyone have any find grained benchmark data? +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/10 +X-Sequence-Number: 10 + +Hi everyone, + +There are PostgreSQL servers around that are handling 2,000 simultaneous +client connections (in real life) without problems, but no-one obvious +seems to have yet taken the time to do fine grained testing of the +servers which can take this kind of load, to accurately model their +performance characteristics. + +Does anyone here happen to have fine grained benchmark/performance +figures hanging around which get into this range of performance? +Preferably with pretty precise details of how the system was configured, +etc. + +:-) + +Regards and best wishes, + +Justin Clift + +-- +"My grandfather once told me that there are two kinds of people: those +who work and those who take the credit. He told me to try to be in the +first group; there was less competition there." + - Indira Gandhi + +From pgsql-performance-owner@postgresql.org Tue Sep 17 06:50:17 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9B7E1475B33 + for ; + Tue, 17 Sep 2002 06:50:15 -0400 (EDT) +Received: from out-mta3.plasa.com (out-mta3.plasa.com [202.134.0.198]) + by postgresql.org (Postfix) with ESMTP id CC016475D91 + for ; + Tue, 17 Sep 2002 06:50:13 -0400 (EDT) +Received: from [61.5.16.47] (helo=portab) + by out-mta3.plasa.com with smtp (Exim 4.10) id 17rFvo-000YjM-00 + for pgsql-performance@postgresql.org; Tue, 17 Sep 2002 17:50:12 +0700 +Message-ID: <000101c25e38$66df87a0$2f10053d@portab> +From: "kopra" +To: +Subject: subscribe +Date: Sat, 14 Sep 2002 19:28:03 +0700 +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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/11 +X-Sequence-Number: 11 + +subscribe + + +------------------------------------------------------------------------------ + > Khusus Pelanggan Telepon DIVRE 2, Tekan 166 untuk mendengarkan pesan Anda + ------------------------------------------------------------------------------ + +From pgsql-general-owner@postgresql.org Thu Sep 26 04:35:33 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 51FFF4763DE + for ; + Thu, 26 Sep 2002 04:35:20 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 9222E476065 + for ; + Thu, 26 Sep 2002 04:35:15 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8Q8aVq12622 + for ; Thu, 26 Sep 2002 14:06:31 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8Q8aUv12612; + Thu, 26 Sep 2002 14:06:31 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 14:05:44 +0530 +MIME-Version: 1.0 +Subject: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D931438.22010.133ADAFA@localhost> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1161 +X-Sequence-Number: 30742 + +Hello all, + +Some time back I posted a query to build a site with 150GB of database. In last +couple of weeks, lots of things were tested at my place and there are some +results and again some concerns. + +This is a long post. Please be patient and read thr. If we win this, I guess we +have a good marketing/advocacy case here..;-) + +First the problems (For those who do not read beyond first page) + +1) Database load time from flat file using copy is very high +2) Creating index takes huge amount of time. +3) Any suggsestions for runtime as data load and query will be going in +parallel. + +Now the details. Note that this is a test run only.. + +Platform:- 4x Xeon2.4GHz/4GB RAM/4x48 SCSI RAID5/72 GB SCSI +RedHat7.2/PostgreSQL7.1.3 + +Database in flat file: +125,000,000 records of around 100 bytes each. +Flat file size 12GB + +Load time: 14581 sec/~8600 rows persec/~ an MB of data per sec. +Create unique composite index on 2 char and a timestamp field: 25226 sec. +Database size on disk: 26GB +Select query: 1.5 sec. for approx. 150 rows. + +Important postgresql.conf settings + +sort_mem = 12000 +shared_buffers = 24000 +fsync=true (Sad but true. Left untouched.. Will that make a difference on +SCSI?) +wal_buffers = 65536 +wal_files = 64 + +Now the requirements + +Initial flat data load: 250GB of data. This has gone up since last query. It +was 150GB earlier.. +Ongoing inserts: 5000/sec. +Number of queries: 4800 queries/hour +Query response time: 10 sec. + + +Now questions. + +1) Instead of copying from a single 12GB data file, will a parallel copy from +say 5 files will speed up the things? + +Couple MB of data per sec. to disk is just not saturating it. It's a RAID 5 +setup.. + +2) Sort mem.=12K i.e. 94MB, sounds good enough to me. Does this need further +addition to improve create index performance? + +3) 5K concurrent inserts with an index on, will this need a additional CPU +power? Like deploying it on dual RISC CPUs etc? + +4) Query performance is not a problem. Though 4.8K queries per sec. expected +response time from each query is 10 sec. But my guess is some serius CPU power +will be chewed there too.. + +5)Will upgrading to 7.2.2/7.3 beta help? + +All in all, in the test, we didn't see the performance where hardware is +saturated to it's limits. So effectively we are not able to get postgresql +making use of it. Just pushing WAL and shared buffers does not seem to be the +solution. + +If you guys have any suggestions. let me know. I need them all.. + +Mysql is almost out because it's creating index for last 17 hours. I don't +think it will keep up with 5K inserts per sec. with index. SAP DB is under +evaluation too. But postgresql is most favourite as of now because it works. So +I need to come up with solutions to problems that will occur in near future.. +;-) + +TIA.. + +Bye + Shridhar + +-- +Law of Procrastination: Procrastination avoids boredom; one never has the +feeling that there is nothing important to do. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 04:53:43 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id E56844768FD + for ; + Thu, 26 Sep 2002 04:53:40 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 2B51C4767DC + for ; + Thu, 26 Sep 2002 04:53:39 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8Q8snQ14266 + for ; Thu, 26 Sep 2002 14:24:49 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8Q8snv14256; + Thu, 26 Sep 2002 14:24:49 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 14:24:02 +0530 +MIME-Version: 1.0 +Subject: Re: [HACKERS] Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D931882.31859.134B9E4C@localhost> +In-reply-to: <3D931438.22010.133ADAFA@localhost> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1162 +X-Sequence-Number: 30743 + +On 26 Sep 2002 at 14:05, Shridhar Daithankar wrote: +> Some time back I posted a query to build a site with 150GB of database. In last +> couple of weeks, lots of things were tested at my place and there are some +> results and again some concerns. + +> 2) Creating index takes huge amount of time. +> Load time: 14581 sec/~8600 rows persec/~ an MB of data per sec. +> Create unique composite index on 2 char and a timestamp field: 25226 sec. +> Database size on disk: 26GB +> Select query: 1.5 sec. for approx. 150 rows. + +> 2) Sort mem.=12K i.e. 94MB, sounds good enough to me. Does this need further +> addition to improve create index performance? + +Just a thought. If I sort the table before making an index, would it be faster +than creating index on raw table? And/or if at all, how do I sort the table +without duplicating it? + +Just a wild thought.. + +Bye + Shridhar + +-- +linux: the choice of a GNU generation(ksh@cis.ufl.edu put this on Tshirts in +'93) + + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:06:18 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id A48884761EA; Thu, 26 Sep 2002 05:06:16 -0400 (EDT) +Received: from svana.org (t1-1-076.dialup.apex.net.au [203.20.62.76]) + by postgresql.org (Postfix) with ESMTP + id B99B24760CD; Thu, 26 Sep 2002 05:06:15 -0400 (EDT) +Received: from kleptog by svana.org with local (Exim 3.35 #1 (Debian)) + id 17uUaF-0002nB-00; Thu, 26 Sep 2002 19:05:19 +1000 +Date: Thu, 26 Sep 2002 19:05:19 +1000 +From: Martijn van Oosterhout +To: Shridhar Daithankar +Cc: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: Performance while loading data and indexing +Message-ID: <20020926090519.GB10471@svana.org> +Reply-To: Martijn van Oosterhout +Mail-Followup-To: Shridhar Daithankar , + pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +References: <3D931438.22010.133ADAFA@localhost> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +In-Reply-To: <3D931438.22010.133ADAFA@localhost> +User-Agent: Mutt/1.3.28i +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1163 +X-Sequence-Number: 30744 + +I'll preface this by saying that while I have a large database, it doesn't +require quite the performace you're talking about here. + +On Thu, Sep 26, 2002 at 02:05:44PM +0530, Shridhar Daithankar wrote: +> 1) Database load time from flat file using copy is very high +> 2) Creating index takes huge amount of time. +> 3) Any suggsestions for runtime as data load and query will be going in +> parallel. + +You're loading all the data in one copy. I find that INSERTs are mostly +limited by indexes. While index lookups are cheap, they are not free and +each index needs to be updated for each row. + +I fond using partial indexes to only index the rows you actually use can +help with the loading. It's a bit obscure though. + +As for parallel loading, you'll be limited mostly by your I/O bandwidth. +Have you measured it to take sure it's up to speed? + +> Now the details. Note that this is a test run only.. +> +> Platform:- 4x Xeon2.4GHz/4GB RAM/4x48 SCSI RAID5/72 GB SCSI +> RedHat7.2/PostgreSQL7.1.3 +> +> Database in flat file: +> 125,000,000 records of around 100 bytes each. +> Flat file size 12GB +> +> Load time: 14581 sec/~8600 rows persec/~ an MB of data per sec. +> Create unique composite index on 2 char and a timestamp field: 25226 sec. +> Database size on disk: 26GB +> Select query: 1.5 sec. for approx. 150 rows. + +So you're loading at a rate of 860KB per sec. That's not too fast. How many +indexes are active at that time? Triggers and foreign keys also take their +toll. + +> Important postgresql.conf settings +> +> sort_mem = 12000 +> shared_buffers = 24000 +> fsync=true (Sad but true. Left untouched.. Will that make a difference on +> SCSI?) +> wal_buffers = 65536 +> wal_files = 64 + +fsync IIRC only affects the WAL buffers now but it may be quite expensive, +especially considering it's running on every transaction commit. Oh, your +WAL files are on a seperate disk from the data? + +> Initial flat data load: 250GB of data. This has gone up since last query. It +> was 150GB earlier.. +> Ongoing inserts: 5000/sec. +> Number of queries: 4800 queries/hour +> Query response time: 10 sec. + +That looks quite acheivable. + +> 1) Instead of copying from a single 12GB data file, will a parallel copy from +> say 5 files will speed up the things? + +Limited by I/O bandwidth. On linux vmstat can tell you how many blocks are +being loaded and stored per second. Try it. As long as sync() doesn't get +done too often, it should be help. + +> Couple MB of data per sec. to disk is just not saturating it. It's a RAID 5 +> setup.. + +No, it's not. You should be able to do better. + +> 2) Sort mem.=12K i.e. 94MB, sounds good enough to me. Does this need further +> addition to improve create index performance? + +Should be fine. Admittedly your indexes are taking rather long to build. + +> 3) 5K concurrent inserts with an index on, will this need a additional CPU +> power? Like deploying it on dual RISC CPUs etc? + +It shouldn't. Do you have an idea of what your CPU usage is? ps aux should +give you a decent idea. + +> 4) Query performance is not a problem. Though 4.8K queries per sec. expected +> response time from each query is 10 sec. But my guess is some serius CPU power +> will be chewed there too.. + +Should be fine. + +> 5)Will upgrading to 7.2.2/7.3 beta help? + +Possibly, though it may be wirth it just for the features/bugfixes. + +> All in all, in the test, we didn't see the performance where hardware is +> saturated to it's limits. So effectively we are not able to get postgresql +> making use of it. Just pushing WAL and shared buffers does not seem to be the +> solution. +> +> If you guys have any suggestions. let me know. I need them all.. + +Find the bottleneck: CPU, I/O or memory? + +> Mysql is almost out because it's creating index for last 17 hours. I don't +> think it will keep up with 5K inserts per sec. with index. SAP DB is under +> evaluation too. But postgresql is most favourite as of now because it works. So +> I need to come up with solutions to problems that will occur in near future.. +> ;-) + +17 hours! Ouch. Either way, you should be able to do much better. Hope this +helps, +-- +Martijn van Oosterhout http://svana.org/kleptog/ +> There are 10 kinds of people in the world, those that can do binary +> arithmetic and those that can't. + +From pgsql-hackers-owner@postgresql.org Thu Sep 26 05:12:58 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 34B1A47616F + for ; + Thu, 26 Sep 2002 05:12:56 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 3DF80475F47 + for ; + Thu, 26 Sep 2002 05:12:53 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8Q9E6m15849 + for ; Thu, 26 Sep 2002 14:44:06 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8Q9E6v15839; + Thu, 26 Sep 2002 14:44:06 +0530 +From: "Shridhar Daithankar" +To: paolo.cassago@talentmanager.com +Date: Thu, 26 Sep 2002 14:43:20 +0530 +MIME-Version: 1.0 +Subject: Re: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Cc: pgsql-hackers@postgresql.org +Message-ID: <3D931D08.1695.135D474B@localhost> +In-reply-to: + <19138.194.185.48.247.1033030286.squirrel@mail.talentwebsolutions.com> +References: <3D931882.31859.134B9E4C@localhost> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1525 +X-Sequence-Number: 29482 + +On 26 Sep 2002 at 10:51, paolo.cassago@talentmanager.c wrote: + +> Hi, +> it seems you have to cluster it, I don't think you have another choise. + +Hmm.. That didn't occur to me...I guess some real time clustering like usogres +would do. Unless it turns out to be a performance hog.. + +But this is just insert and select. No updates no deletes(Unless customer makes +a 180 degree turn) So I doubt if clustering will help. At the most I can +replicate data across machines and spread queries on them. Replication overhead +as a down side and low query load on each machine as upside.. + +> I'm retrieving the configuration of our postgres servers (I'm out of office +> now), so I can send it to you. I was quite disperate about performance, and +> I was thinking to migrate the data on an oracle database. Then I found this +> configuration on the net, and I had a succesfull increase of performance. + +In this case, we are upto postgresql because we/our customer wants to keep the +costs down..:-) Even they are asking now if it's possible to keep hardware +costs down as well. That's getting some funny responses here but I digress.. + +> Maybe this can help you. +> +> Why you use copy to insert records? I usually use perl scripts, and they +> work well . + +Performance reasons. As I said in one of my posts earlier, putting upto 100K +records in one transaction in steps of 10K did not reach performance of copy. +As Tom said rightly, it was a 4-1 ratio despite using transactions.. + +Thanks once again.. +Bye + Shridhar + +-- +Secretary's Revenge: Filing almost everything under "the". + + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:17:41 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id C6DFF4763DE; Thu, 26 Sep 2002 05:17:39 -0400 (EDT) +Received: from new-smtp2.ihug.com.au (new-smtp2.ihug.com.au [203.109.250.28]) + by postgresql.org (Postfix) with ESMTP + id 24E4847631F; Thu, 26 Sep 2002 05:17:39 -0400 (EDT) +Received: from p555-tnt2.mel.ihug.com.au (postgresql.org) [203.173.166.47] + by new-smtp2.ihug.com.au with esmtp (Exim 3.22 #1 (Debian)) + id 17uUm7-00005d-00; Thu, 26 Sep 2002 19:17:35 +1000 +Message-ID: <3D92D0AC.CE6114C4@postgresql.org> +Date: Thu, 26 Sep 2002 19:17:32 +1000 +From: Justin Clift +X-Mailer: Mozilla 4.79 [en] (WinNT; U) +X-Accept-Language: en +MIME-Version: 1.0 +To: shridhar_daithankar@persistent.co.in +Cc: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: Performance while loading data and indexing +References: <3D931438.22010.133ADAFA@localhost> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1164 +X-Sequence-Number: 30745 + +Hi Shridhar, + +Shridhar Daithankar wrote: + +> 3) Any suggsestions for runtime as data load and query will be going in +> parallel. + +That sounds unusual. From reading this, it *sounds* like you'll be +running queries against an incomplete dataset, or maybe just running the +queries that affect the tables loaded thus far (during the initial +load). + + +> fsync=true (Sad but true. Left untouched.. Will that make a difference on +> SCSI?) + +Definitely. Have directly measured a ~ 2x tps throughput increase on +FreeBSD when leaving fsync off whilst performance measuring stuff +recently (PG 7.2.2). Like anything it'll depend on workload, phase of +moon, etc, but it's a decent indicator. + + +> Now questions. +> +> 1) Instead of copying from a single 12GB data file, will a parallel copy from +> say 5 files will speed up the things? + +Not sure yet. Haven't get done enough performance testing (on the cards +very soon though). + +> Couple MB of data per sec. to disk is just not saturating it. It's a RAID 5 +> setup.. + +fsync = off would help during the data load, but not a good idea if +you're going to be running queries against it at the same time. + +Am still getting the hang of performance tuning stuff. Have a bunch of +Ultra160 hardware for the Intel platform, and am testing against it as +time permits. + +Not as high end as I'd like, but it's a start. + +:-) + +Regards and best wishes, + +Justin Clift + + +> Bye +> Shridhar + +-- +"My grandfather once told me that there are two kinds of people: those +who work and those who take the credit. He told me to try to be in the +first group; there was less competition there." + - Indira Gandhi + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:35:14 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id C25DF47644C + for ; + Thu, 26 Sep 2002 05:35:13 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 0925D47616F + for ; + Thu, 26 Sep 2002 05:35:10 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8Q9aQg18125 + for ; Thu, 26 Sep 2002 15:06:26 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8Q9aQv18115; + Thu, 26 Sep 2002 15:06:26 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 15:05:40 +0530 +MIME-Version: 1.0 +Subject: Re: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D932244.13502.1371B9CA@localhost> +In-reply-to: <3D92D0AC.CE6114C4@postgresql.org> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1166 +X-Sequence-Number: 30747 + +On 26 Sep 2002 at 19:17, Justin Clift wrote: +> Shridhar Daithankar wrote: +> +> > 3) Any suggsestions for runtime as data load and query will be going in +> > parallel. +> +> That sounds unusual. From reading this, it *sounds* like you'll be +> running queries against an incomplete dataset, or maybe just running the +> queries that affect the tables loaded thus far (during the initial +> load). + +That's correct. Load the data so far and keep inserting data as and when it +generates. + +They don't mind running against data so far. It's not very accurate stuff +IMO... + +> > fsync=true (Sad but true. Left untouched.. Will that make a difference on +> > SCSI?) +> +> Definitely. Have directly measured a ~ 2x tps throughput increase on +> FreeBSD when leaving fsync off whilst performance measuring stuff +> recently (PG 7.2.2). Like anything it'll depend on workload, phase of +> moon, etc, but it's a decent indicator. + +I didn't know even that matters with SCSI..Will check out.. + +> fsync = off would help during the data load, but not a good idea if +> you're going to be running queries against it at the same time. + +That's OK for the reasons mentioned above. It wouldn't be out of place to +expect a UPS to such an installation... + +Bye + Shridhar + +-- +Hoare's Law of Large Problems: Inside every large problem is a small problem +struggling to get out. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:46:29 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 75E39476B20 + for ; + Thu, 26 Sep 2002 05:46:27 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 548F847644C + for ; + Thu, 26 Sep 2002 05:46:23 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8Q9la019303 + for ; Thu, 26 Sep 2002 15:17:36 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8Q9lav19293; + Thu, 26 Sep 2002 15:17:36 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 15:16:50 +0530 +MIME-Version: 1.0 +Subject: Re: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D9324E2.30195.137BF348@localhost> +In-reply-to: <20020926090519.GB10471@svana.org> +References: <3D931438.22010.133ADAFA@localhost> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1167 +X-Sequence-Number: 30748 + +On 26 Sep 2002 at 19:05, Martijn van Oosterhout wrote: + +> On Thu, Sep 26, 2002 at 02:05:44PM +0530, Shridhar Daithankar wrote: +> > 1) Database load time from flat file using copy is very high +> > 2) Creating index takes huge amount of time. +> > 3) Any suggsestions for runtime as data load and query will be going in +> > parallel. +> +> You're loading all the data in one copy. I find that INSERTs are mostly +> limited by indexes. While index lookups are cheap, they are not free and +> each index needs to be updated for each row. +> +> I fond using partial indexes to only index the rows you actually use can +> help with the loading. It's a bit obscure though. +> +> As for parallel loading, you'll be limited mostly by your I/O bandwidth. +> Have you measured it to take sure it's up to speed? + +Well. It's like this, as of now.. CreateDB->create table->create index->Select. + +So loading is not slowed by index. As of your hint of vmstat, will check it +out. +> So you're loading at a rate of 860KB per sec. That's not too fast. How many +> indexes are active at that time? Triggers and foreign keys also take their +> toll. + +Nothing except the table where data os loaded.. + +> fsync IIRC only affects the WAL buffers now but it may be quite expensive, +> especially considering it's running on every transaction commit. Oh, your +> WAL files are on a seperate disk from the data? + +No. Same RAID 5 disks.. + +> It shouldn't. Do you have an idea of what your CPU usage is? ps aux should +> give you a decent idea. + +I guess we forgot to monitor system parameters. Next on my list is running +vmstat, top and tuning bdflush. + +> Find the bottleneck: CPU, I/O or memory? + +Understood.. +> +> > Mysql is almost out because it's creating index for last 17 hours. I don't +> > think it will keep up with 5K inserts per sec. with index. SAP DB is under +> > evaluation too. But postgresql is most favourite as of now because it works. So +> > I need to come up with solutions to problems that will occur in near future.. +> > ;-) +> +> 17 hours! Ouch. Either way, you should be able to do much better. Hope this +> helps, + +Heh.. no wonder this evaluation is taking more than 2 weeks.. Mysql was running +out of disk space while creating index and crashin. An upgrade to mysql helped +there but no numbers as yet.. + +Thanks once again... +Bye + Shridhar + +-- +Boren's Laws: (1) When in charge, ponder. (2) When in trouble, delegate. (3) +When in doubt, mumble. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:59:51 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 13499476C17 + for ; + Thu, 26 Sep 2002 05:59:51 -0400 (EDT) +Received: from anchor-post-39.mail.demon.net (anchor-post-39.mail.demon.net + [194.217.242.80]) + by postgresql.org (Postfix) with ESMTP id 76F3C476C01 + for ; + Thu, 26 Sep 2002 05:59:50 -0400 (EDT) +Received: from mwynhau.demon.co.uk ([193.237.186.96] + helo=mainbox.archonet.com) + by anchor-post-39.mail.demon.net with esmtp (Exim 3.36 #2) + id 17uVR1-0003WF-0U; Thu, 26 Sep 2002 10:59:51 +0100 +Received: from localhost (localhost.localdomain [127.0.0.1]) + by mainbox.archonet.com (Postfix) with ESMTP + id 5B12716378; Thu, 26 Sep 2002 10:49:02 +0100 (BST) +Received: from client.archonet.com (client.archonet.com [192.168.1.16]) + by mainbox.archonet.com (Postfix) with ESMTP + id AE86216367; Thu, 26 Sep 2002 10:49:01 +0100 (BST) +Content-Type: text/plain; + charset="iso-8859-1" +From: Richard Huxton +Organization: Archonet Ltd +To: shridhar_daithankar@persistent.co.in, + pgsql-general@postgresql.org +Subject: Re: Performance while loading data and indexing +Date: Thu, 26 Sep 2002 10:48:06 +0100 +User-Agent: KMail/1.4.1 +References: <3D931438.22010.133ADAFA@localhost> +In-Reply-To: <3D931438.22010.133ADAFA@localhost> +MIME-Version: 1.0 +Content-Transfer-Encoding: quoted-printable +Message-Id: <200209261048.07761.dev@archonet.com> +X-Virus-Scanned: by AMaViS snapshot-20020531 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1172 +X-Sequence-Number: 30753 + +On Thursday 26 Sep 2002 9:35 am, Shridhar Daithankar wrote: + +[questions re: large database] + +Before reading my advice please bear in mind you are operating way beyond t= +he=20 +scale of anything I have ever built. + +> Now the details. Note that this is a test run only.. +> +> Platform:- 4x Xeon2.4GHz/4GB RAM/4x48 SCSI RAID5/72 GB SCSI +> RedHat7.2/PostgreSQL7.1.3 +> +> Database in flat file: +> 125,000,000 records of around 100 bytes each. +> Flat file size 12GB +> +> Load time: 14581 sec/~8600 rows persec/~ an MB of data per sec. +> Create unique composite index on 2 char and a timestamp field: 25226 sec. +> Database size on disk: 26GB +> Select query: 1.5 sec. for approx. 150 rows. +> +> Important postgresql.conf settings +[snipped setting details for moment] + +Have you tried putting the wal files, syslog etc on separate disks/volumes?= + If=20 +you've settled on Intel, about the only thing you can optimise further is t= +he=20 +disks. + +Oh - and the OS - make sure you're running a (good) recent kernel for that= +=20 +sort of hardware, I seem to remember some substantial changes in the 2.4=20 +series regarding multi-processor. + +> Now the requirements +> +> Initial flat data load: 250GB of data. This has gone up since last query. +> It was 150GB earlier.. +> Ongoing inserts: 5000/sec. +> Number of queries: 4800 queries/hour +> Query response time: 10 sec. + +Is this 5000 rows in say 500 transactions or 5000 insert transactions per= +=20 +second. How many concurrent clients is this? Similarly for the 4800 queries= +,=20 +how many concurrent clients is this? Are they expected to return approx 150= +=20 +rows as in your test? + +> Now questions. +> +> 1) Instead of copying from a single 12GB data file, will a parallel copy +> from say 5 files will speed up the things? + +If the CPU is the bottle-neck then it should, but it's difficult to say=20 +without figures. + +> Couple MB of data per sec. to disk is just not saturating it. It's a RAID= + 5 +> setup.. + +What is saturating during the flat-file load? Something must be maxed in to= +p /=20 +iostat / vmstat. + +[snip] +> +> 5)Will upgrading to 7.2.2/7.3 beta help? + +It's unlikely to hurt. + +> All in all, in the test, we didn't see the performance where hardware is +> saturated to it's limits. + +Something *must* be. + +What are your disaster recovery plans? I can see problems with taking backu= +ps=20 +if this beast is live 24/7. + +- Richard Huxton + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:50:02 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 6D16F4761DF; Thu, 26 Sep 2002 05:50:00 -0400 (EDT) +Received: from new-smtp2.ihug.com.au (new-smtp2.ihug.com.au [203.109.250.28]) + by postgresql.org (Postfix) with ESMTP + id 79EAE47616F; Thu, 26 Sep 2002 05:49:59 -0400 (EDT) +Received: from p555-tnt2.mel.ihug.com.au (postgresql.org) [203.173.166.47] + by new-smtp2.ihug.com.au with esmtp (Exim 3.22 #1 (Debian)) + id 17uVHP-000184-00; Thu, 26 Sep 2002 19:49:55 +1000 +Message-ID: <3D92D841.3E02B2A8@postgresql.org> +Date: Thu, 26 Sep 2002 19:49:53 +1000 +From: Justin Clift +X-Mailer: Mozilla 4.79 [en] (WinNT; U) +X-Accept-Language: en +MIME-Version: 1.0 +To: shridhar_daithankar@persistent.co.in +Cc: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <3D932244.13502.1371B9CA@localhost> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1168 +X-Sequence-Number: 30749 + +Shridhar Daithankar wrote: + +> > > fsync=true (Sad but true. Left untouched.. Will that make a difference on +> > > SCSI?) +> > +> > Definitely. Have directly measured a ~ 2x tps throughput increase on +> > FreeBSD when leaving fsync off whilst performance measuring stuff +> > recently (PG 7.2.2). Like anything it'll depend on workload, phase of +> > moon, etc, but it's a decent indicator. +> +> I didn't know even that matters with SCSI..Will check out.. + +Cool. When testing it had FreeBSD 4.6.2 installed on one drive along +with the PostgreSQL 7.2.2 binaries, it had the data on a second drive +(mounted as /pgdata), and it had the pg_xlog directory mounted on a +third drive. Swap had it's own drive as well. + +Everything is UltraSCSI, etc. Haven't yet tested for a performance +difference through moving the indexes to another drive after creation +though. That apparently has the potential to help as well. + +:-) + +Regards and best wishes, + +Justin Clift + +-- +"My grandfather once told me that there are two kinds of people: those +who work and those who take the credit. He told me to try to be in the +first group; there was less competition there." + - Indira Gandhi + +From pgsql-general-owner@postgresql.org Thu Sep 26 05:56:37 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 7E7F9476B72; Thu, 26 Sep 2002 05:56:36 -0400 (EDT) +Received: from new-smtp2.ihug.com.au (new-smtp2.ihug.com.au [203.109.250.28]) + by postgresql.org (Postfix) with ESMTP + id 4AB45476B45; Thu, 26 Sep 2002 05:56:34 -0400 (EDT) +Received: from p555-tnt2.mel.ihug.com.au (postgresql.org) [203.173.166.47] + by new-smtp2.ihug.com.au with esmtp (Exim 3.22 #1 (Debian)) + id 17uVNr-0001Ml-00; Thu, 26 Sep 2002 19:56:35 +1000 +Message-ID: <3D92D9D2.64CF55F7@postgresql.org> +Date: Thu, 26 Sep 2002 19:56:34 +1000 +From: Justin Clift +X-Mailer: Mozilla 4.79 [en] (WinNT; U) +X-Accept-Language: en +MIME-Version: 1.0 +To: shridhar_daithankar@persistent.co.in +Cc: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <3D931438.22010.133ADAFA@localhost> + <3D9324E2.30195.137BF348@localhost> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1171 +X-Sequence-Number: 30752 + +Shridhar Daithankar wrote: +> +> On 26 Sep 2002 at 19:05, Martijn van Oosterhout wrote: + +> > fsync IIRC only affects the WAL buffers now but it may be quite expensive, +> > especially considering it's running on every transaction commit. Oh, your +> > WAL files are on a seperate disk from the data? +> +> No. Same RAID 5 disks.. + +Not sure if this is a good idea. Would have to think deeply about the +controller and drive optimisation/load characteristics. + +If it's any help, when I was testing recently with WAL on a separate +drive, the WAL logs were doing more read&writes per second than the main +data drive. This would of course be affected by the queries you are +running against the database. I was just running Tatsuo's TPC-B stuff, +and the OSDB AS3AP tests. + +> I guess we forgot to monitor system parameters. Next on my list is running +> vmstat, top and tuning bdflush. + +That'll just be the start of it for serious performance tuning and +learning how PostgreSQL works. :) + + +> Thanks once again... +> Bye +> Shridhar + +-- +"My grandfather once told me that there are two kinds of people: those +who work and those who take the credit. He told me to try to be in the +first group; there was less competition there." + - Indira Gandhi + +From pgsql-general-owner@postgresql.org Thu Sep 26 10:34:21 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 05F75476AA7; Thu, 26 Sep 2002 10:34:20 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP + id 6AFEC4767D7; Thu, 26 Sep 2002 10:34:18 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.5/8.12.5) with ESMTP id g8QEXwhR003937; + Thu, 26 Sep 2002 10:33:58 -0400 (EDT) +To: shridhar_daithankar@persistent.co.in +Cc: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: Performance while loading data and indexing +In-reply-to: <3D931438.22010.133ADAFA@localhost> +References: <3D931438.22010.133ADAFA@localhost> +Comments: In-reply-to "Shridhar Daithankar" + + message dated "Thu, 26 Sep 2002 14:05:44 +0530" +Date: Thu, 26 Sep 2002 10:33:58 -0400 +Message-ID: <3936.1033050838@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1181 +X-Sequence-Number: 30762 + +"Shridhar Daithankar" writes: +> RedHat7.2/PostgreSQL7.1.3 + +I'd suggest a newer release of Postgres ... 7.1.3 is pretty old ... + +> Create unique composite index on 2 char and a timestamp field: 25226 sec. + +What do you mean by "char" exactly? If it's really char(N), how much +are you paying in padding space? There are very very few cases where +I'd not say to use varchar(N), or text, instead. Also, does it have to +be character data? If you could use an integer or float datatype +instead the index operations should be faster (though I can't say by +how much). Have you thought carefully about the order in which the +composite index columns are listed? + +> sort_mem = 12000 + +To create an index of this size, you want to push sort_mem as high as it +can go without swapping. 12000 sounds fine for the global setting, but +in the process that will create the index, try setting sort_mem to some +hundreds of megs or even 1Gb. (But be careful: the calculation of space +actually used by CREATE INDEX is off quite a bit in pre-7.3 releases +:-(. You should probably expect the actual process size to grow to two +or three times what you set sort_mem to. Don't let it get so big as to +swap.) + +> wal_buffers = 65536 + +The above is a complete waste of memory space, which would be better +spent on letting the kernel expand its disk cache. There's no reason +for wal_buffers to be more than a few dozen. + + regards, tom lane + +From pgsql-general-owner@postgresql.org Thu Sep 26 10:42:11 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 45ACE476D3D; Thu, 26 Sep 2002 10:42:11 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP + id B5B5B476D3A; Thu, 26 Sep 2002 10:42:10 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.5/8.12.5) with ESMTP id g8QEg8hR004032; + Thu, 26 Sep 2002 10:42:09 -0400 (EDT) +To: Justin Clift +Cc: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +In-reply-to: <3D92D9D2.64CF55F7@postgresql.org> +References: <3D931438.22010.133ADAFA@localhost> + <3D9324E2.30195.137BF348@localhost> + <3D92D9D2.64CF55F7@postgresql.org> +Comments: In-reply-to Justin Clift + message dated "Thu, 26 Sep 2002 19:56:34 +1000" +Date: Thu, 26 Sep 2002 10:42:08 -0400 +Message-ID: <4031.1033051328@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1183 +X-Sequence-Number: 30764 + +Justin Clift writes: +>> On 26 Sep 2002 at 19:05, Martijn van Oosterhout wrote: +>>> fsync IIRC only affects the WAL buffers now but it may be quite expensive, +>>> especially considering it's running on every transaction commit. Oh, your +>>> WAL files are on a seperate disk from the data? + +> Not sure if this is a good idea. Would have to think deeply about the +> controller and drive optimisation/load characteristics. + +> If it's any help, when I was testing recently with WAL on a separate +> drive, the WAL logs were doing more read&writes per second than the main +> data drive. + +... but way fewer seeks. For anything involving lots of updating +transactions (and certainly 5000 separate insertions per second would +qualify; can those be batched??), it should be a win to put WAL on its +own spindle, just to get locality of access to the WAL. + + regards, tom lane + +From pgsql-general-owner@postgresql.org Thu Sep 26 10:51:34 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id DEDD4475EE4 + for ; + Thu, 26 Sep 2002 10:51:33 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 4CAFB475CB4 + for ; + Thu, 26 Sep 2002 10:51:32 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8QEqqK15165 + for ; Thu, 26 Sep 2002 20:22:52 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8QEqqv15154; + Thu, 26 Sep 2002 20:22:52 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 20:22:05 +0530 +MIME-Version: 1.0 +Subject: Re: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D936C6D.12380.14936AEC@localhost> +References: <3D931438.22010.133ADAFA@localhost> +In-reply-to: <3936.1033050838@sss.pgh.pa.us> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1187 +X-Sequence-Number: 30768 + +On 26 Sep 2002 at 10:33, Tom Lane wrote: + +> "Shridhar Daithankar" writes: +> > RedHat7.2/PostgreSQL7.1.3 +> +> I'd suggest a newer release of Postgres ... 7.1.3 is pretty old ... + +I agree.. downloadind 7.2.2 right away.. + +> > Create unique composite index on 2 char and a timestamp field: 25226 sec. +> +> What do you mean by "char" exactly? If it's really char(N), how much +> are you paying in padding space? There are very very few cases where +> I'd not say to use varchar(N), or text, instead. Also, does it have to +> be character data? If you could use an integer or float datatype +> instead the index operations should be faster (though I can't say by +> how much). Have you thought carefully about the order in which the +> composite index columns are listed? + +I have forwarded the idea of putting things into number. If it causes speedup +in index lookup/creation, it would do. Looks like bigint is the order of the +day.. + +> +> > sort_mem = 12000 +> +> To create an index of this size, you want to push sort_mem as high as it +> can go without swapping. 12000 sounds fine for the global setting, but +> in the process that will create the index, try setting sort_mem to some +> hundreds of megs or even 1Gb. (But be careful: the calculation of space +> actually used by CREATE INDEX is off quite a bit in pre-7.3 releases +> :-(. You should probably expect the actual process size to grow to two +> or three times what you set sort_mem to. Don't let it get so big as to +> swap.) + +Great. I was skeptical to push it beyond 100MB. Now I can push it to corners.. + +> > wal_buffers = 65536 +> +> The above is a complete waste of memory space, which would be better +> spent on letting the kernel expand its disk cache. There's no reason +> for wal_buffers to be more than a few dozen. + +That was a rather desparate move. Nothing was improving performance and then we +started pushing numbers.. WIll get it back.. Same goes for 64 WAL files.. A GB +looks like waste to me.. + +I might have found the bottleneck, although by accident. Mysql was running out +of space while creating index. So my friend shut down mysql and tried to move +things by hand to create links. He noticed that even things like cp were +terribly slow and it hit us.. May be the culprit is the file system. Ext3 in +this case. + +My friend argues for ext2 to eliminate journalling overhead but I favour +reiserfs personally having used it in pgbench with 10M rows on paltry 20GB IDE +disk for 25 tps.. + +We will be attempting raiserfs and/or XFS if required. I know how much speed +difference exists between resiserfs and ext2. Would not be surprised if +everythng just starts screaming in one go.. + +Bye + Shridhar + +-- +Cropp's Law: The amount of work done varies inversly with the time spent in the +office. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 10:57:42 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 79B71476141 + for ; + Thu, 26 Sep 2002 10:57:41 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 0C288475FBD + for ; + Thu, 26 Sep 2002 10:57:40 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8QEww115498 + for ; Thu, 26 Sep 2002 20:28:58 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8QEwwv15488; + Thu, 26 Sep 2002 20:28:58 +0530 +From: "Shridhar Daithankar" +To: pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Date: Thu, 26 Sep 2002 20:28:11 +0530 +MIME-Version: 1.0 +Subject: Re: [HACKERS] Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Message-ID: <3D936DDB.26585.14990280@localhost> +References: <3D92D9D2.64CF55F7@postgresql.org> +In-reply-to: <4031.1033051328@sss.pgh.pa.us> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1188 +X-Sequence-Number: 30769 + +On 26 Sep 2002 at 10:42, Tom Lane wrote: + +> Justin Clift writes: +> > If it's any help, when I was testing recently with WAL on a separate +> > drive, the WAL logs were doing more read&writes per second than the main +> > data drive. +> +> ... but way fewer seeks. For anything involving lots of updating +> transactions (and certainly 5000 separate insertions per second would +> qualify; can those be batched??), it should be a win to put WAL on its +> own spindle, just to get locality of access to the WAL. + +Probably they will be a single transcation. If possible we will bunch more of +them together.. like 5 seconds of data pushed down in a single transaction but +not sure it's possible.. + +This is bit like replication but from live oracle machine to postgres, from +information I have. So there should be some chance of tuning there.. + +Bye + Shridhar + +-- +Langsam's Laws: (1) Everything depends. (2) Nothing is always. (3) Everything +is sometimes. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 11:07:07 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id B7B27476D50; Thu, 26 Sep 2002 11:07:06 -0400 (EDT) +Received: from mx.webmailstation.com (mx.webmailstation.com [64.23.55.10]) + by postgresql.org (Postfix) with ESMTP + id 24B2C476D4E; Thu, 26 Sep 2002 11:07:06 -0400 (EDT) +Received: from dyp (localhost.localdomain [127.0.0.1]) + by mx.webmailstation.com (Postfix) with ESMTP + id 202E51F85F; Thu, 26 Sep 2002 07:04:18 -0400 (EDT) +Content-Type: text/plain; + charset="iso-8859-1" +From: Denis Perchine +Organization: AcademSoft Ltd. +To: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +Date: Thu, 26 Sep 2002 22:04:41 +0700 +User-Agent: KMail/1.4.3 +References: <3D931438.22010.133ADAFA@localhost> + <3D936C6D.12380.14936AEC@localhost> +In-Reply-To: <3D936C6D.12380.14936AEC@localhost> +MIME-Version: 1.0 +Content-Transfer-Encoding: 8bit +Message-Id: <200209262204.41638.dyp@perchine.com> +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1189 +X-Sequence-Number: 30770 + +On Thursday 26 September 2002 21:52, Shridhar Daithankar wrote: + +> I might have found the bottleneck, although by accident. Mysql was running +> out of space while creating index. So my friend shut down mysql and tried +> to move things by hand to create links. He noticed that even things like cp +> were terribly slow and it hit us.. May be the culprit is the file system. +> Ext3 in this case. +> +> My friend argues for ext2 to eliminate journalling overhead but I favour +> reiserfs personally having used it in pgbench with 10M rows on paltry 20GB +> IDE disk for 25 tps.. +> +> We will be attempting raiserfs and/or XFS if required. I know how much +> speed difference exists between resiserfs and ext2. Would not be surprised +> if everythng just starts screaming in one go.. + +As it was found by someone before any non-journaling FS is faster than +journaling one. This due to double work done by FS and database. + +Try it on ext2 and compare. + +-- +Denis + + +From pgsql-general-owner@postgresql.org Thu Sep 26 11:12:48 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id E29E6476D79; Thu, 26 Sep 2002 11:12:47 -0400 (EDT) +Received: from new-smtp2.ihug.com.au (new-smtp2.ihug.com.au [203.109.250.28]) + by postgresql.org (Postfix) with ESMTP + id 1E9DC476D76; Thu, 26 Sep 2002 11:12:47 -0400 (EDT) +Received: from p407-tnt2.mel.ihug.com.au (postgresql.org) [203.173.165.153] + by new-smtp2.ihug.com.au with esmtp (Exim 3.22 #1 (Debian)) + id 17uaJu-00033K-00; Fri, 27 Sep 2002 01:12:50 +1000 +Message-ID: <3D9323F1.3A534EA8@postgresql.org> +Date: Fri, 27 Sep 2002 01:12:49 +1000 +From: Justin Clift +X-Mailer: Mozilla 4.79 [en] (WinNT; U) +X-Accept-Language: en +MIME-Version: 1.0 +To: shridhar_daithankar@persistent.co.in, + PostgreSQL Performance Mailing List +Cc: PostgreSQL Hackers Mailing List , + PostgreSQL General Mailing List +Subject: Re: Performance while loading data and indexing +References: <3D931438.22010.133ADAFA@localhost> + <3D936C6D.12380.14936AEC@localhost> +Content-Type: text/plain; charset=us-ascii +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1191 +X-Sequence-Number: 30772 + +Shridhar Daithankar wrote: + +> My friend argues for ext2 to eliminate journalling overhead but I favour +> reiserfs personally having used it in pgbench with 10M rows on paltry 20GB IDE +> disk for 25 tps.. + +If it's any help, the setup I mentioned before with differnt disks for +the data and the WAL files was getting an average of about 72 tps with +200 concurrent users on pgbench. Haven't tuned it in a hard core way at +all, and it only has 256MB DDR RAM in it at the moment (single CPU +AthonXP 1600). These are figures made during the 2.5k+ test runs of +pgbench done when developing pg_autotune recently. + +As a curiosity point, how predictable are the queries you're going to be +running on your database? They sound very simple and very predicatable. + +The pg_autotune tool might be your friend here. It can deal with +arbitrary SQL instead of using the pg_bench stuff of Tatsuos, and it can +also deal with an already loaded database. You'd just have to tweak the +names of the tables that it vacuums and the names of the indexes that it +reindexes between each run, to get some idea of your overall server +performance at different load points. + +Probably worth taking a good look at if you're not afraid of editing +variables in C code. :) + +> We will be attempting raiserfs and/or XFS if required. I know how much speed +> difference exists between resiserfs and ext2. Would not be surprised if +> everythng just starts screaming in one go.. + +We'd all probably be interested to hear this. Added the PostgreSQL +"Performance" mailing list to this thread too, Just In Case. (wow that's +a lot of cross posting now). + +Regards and best wishes, + +Justin Clift + +> Bye +> Shridhar +> +> -- +> Cropp's Law: The amount of work done varies inversly with the time spent in the +> office. +> +> ---------------------------(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 + +-- +"My grandfather once told me that there are two kinds of people: those +who work and those who take the credit. He told me to try to be in the +first group; there was less competition there." + - Indira Gandhi + +From pgsql-general-owner@postgresql.org Thu Sep 26 11:28:32 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 48544476CC6 + for ; + Thu, 26 Sep 2002 11:28:30 -0400 (EDT) +Received: from www.pspl.co.in (www.pspl.co.in [202.54.11.65]) + by postgresql.org (Postfix) with ESMTP id 42D14476B61 + for ; + Thu, 26 Sep 2002 11:28:28 -0400 (EDT) +Received: (from root@localhost) + by www.pspl.co.in (8.11.6/8.11.6) id g8QFTm217943 + for ; Thu, 26 Sep 2002 20:59:48 +0530 +Received: from daithan (daithan.intranet.pspl.co.in [192.168.7.161]) + by www.pspl.co.in (8.11.6/8.11.0) with ESMTP id g8QFTmv17928; + Thu, 26 Sep 2002 20:59:48 +0530 +From: "Shridhar Daithankar" +To: PostgreSQL Performance Mailing List +Date: Thu, 26 Sep 2002 20:59:01 +0530 +MIME-Version: 1.0 +Subject: Re: Performance while loading data and indexing +Reply-To: shridhar_daithankar@persistent.co.in +Cc: PostgreSQL Hackers Mailing List , + PostgreSQL General Mailing List +Message-ID: <3D937515.11546.14B53C07@localhost> +In-reply-to: <3D9323F1.3A534EA8@postgresql.org> +X-mailer: Pegasus Mail for Windows (v4.02) +Content-type: text/plain; charset=US-ASCII +Content-transfer-encoding: 7BIT +Content-description: Mail message body +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1193 +X-Sequence-Number: 30774 + +On 27 Sep 2002 at 1:12, Justin Clift wrote: + +> Shridhar Daithankar wrote: +> As a curiosity point, how predictable are the queries you're going to be +> running on your database? They sound very simple and very predicatable. + +Mostly predictable selects. Not a domain expert on telecom so not very sure. +But in my guess prepare statement in 7.3 should come pretty handy. i.e. by the +time we finish evaluation and test deployment, 7.3 will be out in next couple +of months to say so. So I would recommend doing it 7.3 way only.. +> +> The pg_autotune tool might be your friend here. It can deal with +> arbitrary SQL instead of using the pg_bench stuff of Tatsuos, and it can +> also deal with an already loaded database. You'd just have to tweak the +> names of the tables that it vacuums and the names of the indexes that it +> reindexes between each run, to get some idea of your overall server +> performance at different load points. +> +> Probably worth taking a good look at if you're not afraid of editing +> variables in C code. :) + +Gladly. We started with altering pgbench here for testing and rapidly settled +to perl generated random queries. Once postgresql wins the evaluation match and +things come to implementation, pg_autotune would be a handy tool. Just that +can't do it right now. Have to fight mysql and SAP DB before that.. + +BTW any performance figures on SAP DB? People here are as it frustrated with it +with difficulties in setting it up. But still.. +> + +> > We will be attempting raiserfs and/or XFS if required. I know how much speed +> > difference exists between resiserfs and ext2. Would not be surprised if +> > everythng just starts screaming in one go.. +> +> We'd all probably be interested to hear this. Added the PostgreSQL +> "Performance" mailing list to this thread too, Just In Case. (wow that's +> a lot of cross posting now). + +I know..;-) Glad that PG list does not have strict policies like no non- +subscriber posting or no attachments.. etc.. + +IMO reiserfs, though journalling one, is faster than ext2 etc. because the way +it handles metadata. Personally I haven't come across ext2 being faster than +reiserfs on few machine here for day to day use. + +I guess I should have a freeBSD CD handy too.. Just to give it a try. If it +comes down to a better VM.. though using 2.4.19 here.. so souldn't matter +much.. + +I will keep you guys posted on file system stuff... Glad that we have much +flexibility with postgresql.. + +Bye + Shridhar + +-- +Bilbo's First Law: You cannot count friends that are all packed up in barrels. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 11:41:47 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 26ED6476D61; Thu, 26 Sep 2002 11:41:46 -0400 (EDT) +Received: from CopelandConsulting.Net (dsl-24293-ld.customer.centurytel.net + [209.142.135.135]) by postgresql.org (Postfix) with ESMTP + id E26AF476D7B; Thu, 26 Sep 2002 11:41:44 -0400 (EDT) +Received: from mouse.copelandconsulting.net (mouse.copelandconsulting.net + [192.168.1.2]) + by CopelandConsulting.Net (8.10.1/8.10.1) with ESMTP id g8QFfWu10941; + Thu, 26 Sep 2002 10:41:32 -0500 (CDT) +X-Trade-Id: +To: shridhar_daithankar@persistent.co.in +Cc: PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <3D936C6D.12380.14936AEC@localhost> +References: <3D931438.22010.133ADAFA@localhost> + <3D936C6D.12380.14936AEC@localhost> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-u8SGzlKGiTZg+qY+QPln" +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 10:41:37 -0500 +Message-Id: <1033054898.17282.9.camel@mouse.copelandconsulting.net> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1196 +X-Sequence-Number: 30777 + +--=-u8SGzlKGiTZg+qY+QPln +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Thu, 2002-09-26 at 09:52, Shridhar Daithankar wrote: +> My friend argues for ext2 to eliminate journalling overhead but I favour= +=20 +> reiserfs personally having used it in pgbench with 10M rows on paltry 20G= +B IDE=20 +> disk for 25 tps.. +>=20 +> We will be attempting raiserfs and/or XFS if required. I know how much sp= +eed=20 +> difference exists between resiserfs and ext2. Would not be surprised if= +=20 +> everythng just starts screaming in one go.. +>=20 + +I'm not sure about reiserfs or ext3 but with XFS, you can create your +log on another disk. Also worth noting is that you can also configure +the size and number of log buffers. There are also some other +performance type enhancements you can fiddle with if you don't mind +risking time stamp consistency in the event of a crash. If your setup +allows for it, you might want to consider using XFS in this +configuration. + +While I have not personally tried moving XFS' log to another device, +I've heard that performance gains can be truly stellar. Assuming memory +allows, twiddling with the log buffering is said to allow for large +strides in performance as well. + +If you do try this, I'd love to hear back about your results and +impressions. + +Greg + + +--=-u8SGzlKGiTZg+qY+QPln +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) + +iD8DBQA9kyqx4lr1bpbcL6kRApydAJ46EfAEimKL7eDNSS7ZMdZlo3VptACfcPL0 +ByvQOwuqz/14LUVP1Oewjsk= +=VHX7 +-----END PGP SIGNATURE----- + +--=-u8SGzlKGiTZg+qY+QPln-- + + +From pgsql-general-owner@postgresql.org Thu Sep 26 12:42:01 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id F1D0F475E83; Thu, 26 Sep 2002 12:41:58 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id 3A9EB476EAE; Thu, 26 Sep 2002 12:41:55 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QGfYc04099; + Thu, 26 Sep 2002 12:41:34 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209261641.g8QGfYc04099@candle.pha.pa.us> +Subject: Re: Performance while loading data and indexing +In-Reply-To: <3D936C6D.12380.14936AEC@localhost> +To: shridhar_daithankar@persistent.co.in +Date: Thu, 26 Sep 2002 12:41:34 -0400 (EDT) +Cc: pgsql-hackers@postgresql.org, pgsql-general@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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1202 +X-Sequence-Number: 30783 + +Shridhar Daithankar wrote: +> I might have found the bottleneck, although by accident. Mysql was running out +> of space while creating index. So my friend shut down mysql and tried to move +> things by hand to create links. He noticed that even things like cp were +> terribly slow and it hit us.. May be the culprit is the file system. Ext3 in +> this case. + +I just added a file system and multi-cpu section to my performance +tuning paper: + + http://www.ca.postgresql.org/docs/momjian/hw_performance/ + +The paper does recommend ext3, but the differences between file systems +are very small. If you are seeing 'cp' as slow, I wonder if it may be +something more general, like poorly tuned hardware or something. You can +use 'dd' to throw some data around the file system and see if that is +showing slowness; compare those numbers to another machine that has +different hardware/OS. + +Also, though ext3 is slower, turning fsync off should make ext3 function +similar to ext2. That would be an interesting test if you suspect ext3. + +-- + 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-general-owner@postgresql.org Thu Sep 26 13:17:12 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id E040F476E77; Thu, 26 Sep 2002 13:17:08 -0400 (EDT) +Received: from varsoon.wireboard.com (www.wireboard.com [216.151.155.101]) + by postgresql.org (Postfix) with ESMTP + id 8FF09476DFA; Thu, 26 Sep 2002 13:17:07 -0400 (EDT) +Received: from doug by varsoon.wireboard.com with local (Exim 3.35 #1) + id 17ucFg-0006dh-00; Thu, 26 Sep 2002 13:16:36 -0400 +To: Greg Copeland +From: Doug cNaught +Cc: shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <3D931438.22010.133ADAFA@localhost> + <3D936C6D.12380.14936AEC@localhost> + <1033054898.17282.9.camel@mouse.copelandconsulting.net> +Date: 26 Sep 2002 13:16:36 -0400 +In-Reply-To: Greg Copeland's message of "26 Sep 2002 10:41:37 -0500" +Message-ID: +Lines: 25 +User-Agent: Gnus/5.0806 (Gnus v5.8.6) Emacs/20.7 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1206 +X-Sequence-Number: 30787 + +Greg Copeland writes: + +> I'm not sure about reiserfs or ext3 but with XFS, you can create your +> log on another disk. Also worth noting is that you can also configure +> the size and number of log buffers. There are also some other +> performance type enhancements you can fiddle with if you don't mind +> risking time stamp consistency in the event of a crash. If your setup +> allows for it, you might want to consider using XFS in this +> configuration. + +You can definitely put the ext3 log on a different disk with 2.4 +kernels. + +Also, if you put the WAL logs on a different disk from the main +database, and mount that partition with 'data=writeback' (ie +metadata-only journaling) ext3 should be pretty fast, since WAL files +are preallocated and there will therefore be almost no metadata +updates. + +You should be able to mount the main database with "data=ordered" (the +default) for good performance and reasonable safety. + +I think putting WAL on its own disk(s) is one of the keys here. + +-Doug + +From pgsql-general-owner@postgresql.org Thu Sep 26 14:14:21 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 8779F476D31; Thu, 26 Sep 2002 13:37:58 -0400 (EDT) +Received: from CopelandConsulting.Net (dsl-24293-ld.customer.centurytel.net + [209.142.135.135]) by postgresql.org (Postfix) with ESMTP + id 61C82476D2E; Thu, 26 Sep 2002 13:37:57 -0400 (EDT) +Received: from mouse.copelandconsulting.net (mouse.copelandconsulting.net + [192.168.1.2]) + by CopelandConsulting.Net (8.10.1/8.10.1) with ESMTP id g8QHapu12099; + Thu, 26 Sep 2002 12:36:51 -0500 (CDT) +X-Trade-Id: +To: Bruce Momjian +Cc: shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <200209261641.g8QGfYc04099@candle.pha.pa.us> +References: <200209261641.g8QGfYc04099@candle.pha.pa.us> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-tyawsElsu3INch108LXq" +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 12:36:57 -0500 +Message-Id: <1033061818.23390.12.camel@mouse.copelandconsulting.net> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1208 +X-Sequence-Number: 30789 + +--=-tyawsElsu3INch108LXq +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Thu, 2002-09-26 at 11:41, Bruce Momjian wrote: +> Shridhar Daithankar wrote: +> > I might have found the bottleneck, although by accident. Mysql was runn= +ing out=20 +> > of space while creating index. So my friend shut down mysql and tried t= +o move=20 +> > things by hand to create links. He noticed that even things like cp wer= +e=20 +> > terribly slow and it hit us.. May be the culprit is the file system. Ex= +t3 in=20 +> > this case.=20 +>=20 +> I just added a file system and multi-cpu section to my performance +> tuning paper: +>=20 +> http://www.ca.postgresql.org/docs/momjian/hw_performance/ +>=20 +> The paper does recommend ext3, but the differences between file systems +> are very small. If you are seeing 'cp' as slow, I wonder if it may be +> something more general, like poorly tuned hardware or something. You can +> use 'dd' to throw some data around the file system and see if that is +> showing slowness; compare those numbers to another machine that has +> different hardware/OS. + + +That's a good point. Also, if you're using IDE, you do need to verify +that you're using DMA and proper PIO mode if at possible. Also, big +performance improvements can be seen by making sure your IDE bus speed +has been properly configured. The drivetweak-gtk and hdparm utilities +can make huge difference in performance. Just be sure you know what the +heck your doing when you mess with those. + +Greg + + +--=-tyawsElsu3INch108LXq +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) + +iD8DBQA9k0W54lr1bpbcL6kRAsTSAJ410S530QfaeTjTxEaICSnzhUbNOwCeNGvr +tTGuXDVz190FH55un7vEjrc= +=HFjK +-----END PGP SIGNATURE----- + +--=-tyawsElsu3INch108LXq-- + + +From pgsql-general-owner@postgresql.org Thu Sep 26 14:13:31 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 27240476DA8; Thu, 26 Sep 2002 13:45:12 -0400 (EDT) +Received: from CopelandConsulting.Net (dsl-24293-ld.customer.centurytel.net + [209.142.135.135]) by postgresql.org (Postfix) with ESMTP + id D8262476D8F; Thu, 26 Sep 2002 13:45:10 -0400 (EDT) +Received: from mouse.copelandconsulting.net (mouse.copelandconsulting.net + [192.168.1.2]) + by CopelandConsulting.Net (8.10.1/8.10.1) with ESMTP id g8QHiGu14092; + Thu, 26 Sep 2002 12:44:16 -0500 (CDT) +X-Trade-Id: +To: Bruce Momjian +Cc: shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <200209261641.g8QGfYc04099@candle.pha.pa.us> +References: <200209261641.g8QGfYc04099@candle.pha.pa.us> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-6mav3WK9RCaVOqe8tRq/" +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 12:44:22 -0500 +Message-Id: <1033062262.23475.16.camel@mouse.copelandconsulting.net> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1207 +X-Sequence-Number: 30788 + +--=-6mav3WK9RCaVOqe8tRq/ +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Thu, 2002-09-26 at 11:41, Bruce Momjian wrote: +> Shridhar Daithankar wrote: +> > I might have found the bottleneck, although by accident. Mysql was runn= +ing out=20 +> > of space while creating index. So my friend shut down mysql and tried t= +o move=20 +> > things by hand to create links. He noticed that even things like cp wer= +e=20 +> > terribly slow and it hit us.. May be the culprit is the file system. Ex= +t3 in=20 +> > this case.=20 +>=20 +> I just added a file system and multi-cpu section to my performance +> tuning paper: +>=20 +> http://www.ca.postgresql.org/docs/momjian/hw_performance/ +>=20 +> The paper does recommend ext3, but the differences between file systems +> are very small. If you are seeing 'cp' as slow, I wonder if it may be +> something more general, like poorly tuned hardware or something. You can +> use 'dd' to throw some data around the file system and see if that is +> showing slowness; compare those numbers to another machine that has +> different hardware/OS. +>=20 +> Also, though ext3 is slower, turning fsync off should make ext3 function +> similar to ext2. That would be an interesting test if you suspect ext3. + +I'm curious as to why you recommended ext3 versus some other (JFS, +XFS). Do you have tests which validate that recommendation or was it a +simple matter of getting the warm fuzzies from familiarity? + +Greg + + +--=-6mav3WK9RCaVOqe8tRq/ +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) + +iD8DBQA9k0d24lr1bpbcL6kRAkGfAJ0en60jxkx1LsCX8HIzsjHgA8MnKQCffW/S +m+nGg6nihDZ/JABT4dNcuGo= +=Itl1 +-----END PGP SIGNATURE----- + +--=-6mav3WK9RCaVOqe8tRq/-- + + +From pgsql-general-owner@postgresql.org Thu Sep 26 14:46:12 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 583924762C6; Thu, 26 Sep 2002 14:46:11 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP + id 9179947606A; Thu, 26 Sep 2002 14:46:09 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.6/8.12.6) with ESMTP id g8QIjU0P015223; + Thu, 26 Sep 2002 12:45:30 -0600 (MDT) +Date: Thu, 26 Sep 2002 12:41:55 -0600 (MDT) +From: "scott.marlowe" +To: Shridhar Daithankar +Cc: , +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <3D931882.31859.134B9E4C@localhost> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailBodyFilter: Message body has not been filtered +X-MailScanner: Found to be clean +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1209 +X-Sequence-Number: 30790 + +If you are seeing very slow performance on a drive set, check dmesg to see +if you're getting SCSI bus errors or something similar. If your drives +aren't properly terminated then the performance will suffer a great deal. + + +From pgsql-general-owner@postgresql.org Thu Sep 26 16:01:20 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 09482476052; Thu, 26 Sep 2002 16:01:18 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id A0F8D474E5C; Thu, 26 Sep 2002 16:01:14 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QK0mG10553; + Thu, 26 Sep 2002 16:00:48 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262000.g8QK0mG10553@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <1033062262.23475.16.camel@mouse.copelandconsulting.net> +To: Greg Copeland +Date: Thu, 26 Sep 2002 16:00:48 -0400 (EDT) +Cc: shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Type: multipart/mixed; boundary=ELM1033070448-26881-0_ +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1211 +X-Sequence-Number: 30792 + +--ELM1033070448-26881-0_ +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII + +Greg Copeland wrote: +> > The paper does recommend ext3, but the differences between file systems +> > are very small. If you are seeing 'cp' as slow, I wonder if it may be +> > something more general, like poorly tuned hardware or something. You can +> > use 'dd' to throw some data around the file system and see if that is +> > showing slowness; compare those numbers to another machine that has +> > different hardware/OS. +> > +> > Also, though ext3 is slower, turning fsync off should make ext3 function +> > similar to ext2. That would be an interesting test if you suspect ext3. +> +> I'm curious as to why you recommended ext3 versus some other (JFS, +> XFS). Do you have tests which validate that recommendation or was it a +> simple matter of getting the warm fuzzies from familiarity? + +I used the attached email as a reference. I just changed the wording to +be: + + 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 and xfs are journal-based, and Reiser is + optimized for small files. Fortunately, the journaling file systems + aren't significantly slower than ext2 so they are probably the best + choice. + +so I don't specifically recommend ext3 anymore. As I remember, ext3 is +good only in that it can read ext2 file systems. I think XFS may be the +best bet. + +Can anyone clarify if "data=writeback" is safe for PostgreSQL. +Specifically, are the data files recovered properly or is this option +only for a filesystem containing WAL? + +-- + 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 + +--ELM1033070448-26881-0_ +Content-Transfer-Encoding: 7bit +Content-Type: text/plain +Content-Disposition: inline; filename="/bjm/perf" + + +--ELM1033070448-26881-0_-- +From pgsql-general-owner@postgresql.org Thu Sep 26 16:42:13 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 5B9B147676D; Thu, 26 Sep 2002 16:42:12 -0400 (EDT) +Received: from bob.samurai.com (bob.samurai.com [205.207.28.75]) + by postgresql.org (Postfix) with ESMTP + id E1D784762B7; Thu, 26 Sep 2002 16:42:11 -0400 (EDT) +Received: from boston.samurai.com (DU179.N224.ResNet.QueensU.CA + [130.15.224.179]) by bob.samurai.com (Postfix) with ESMTP + id E9B1A1EAC; Thu, 26 Sep 2002 16:42:10 -0400 (EDT) +To: Bruce Momjian +Cc: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209261641.g8QGfYc04099@candle.pha.pa.us> +From: Neil Conway +In-Reply-To: <200209261641.g8QGfYc04099@candle.pha.pa.us> +Date: 26 Sep 2002 16:41:49 -0400 +Message-ID: <871y7g1o1e.fsf@mailbox.samurai.com> +Lines: 20 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1212 +X-Sequence-Number: 30793 + +Bruce Momjian writes: +> The paper does recommend ext3, but the differences between file systems +> are very small. + +Well, I only did a very rough benchmark (a few runs of pgbench), but +the results I found were drastically different: ext2 was significantly +faster (~50%) than ext3-writeback, which was in turn significantly +faster (~25%) than ext3-ordered. + +> Also, though ext3 is slower, turning fsync off should make ext3 function +> similar to ext2. + +Why would that be? + +Cheers, + +Neil + +-- +Neil Conway || PGP Key ID: DB3C29FC + + +From pgsql-general-owner@postgresql.org Thu Sep 26 16:46:10 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id AD961476147; Thu, 26 Sep 2002 16:46:07 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id C734B476052; Thu, 26 Sep 2002 16:46:05 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QKjtv21744; + Thu, 26 Sep 2002 16:45:55 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262045.g8QKjtv21744@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <871y7g1o1e.fsf@mailbox.samurai.com> +To: Neil Conway +Date: Thu, 26 Sep 2002 16:45:54 -0400 (EDT) +Cc: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1213 +X-Sequence-Number: 30794 + +Neil Conway wrote: +> Bruce Momjian writes: +> > The paper does recommend ext3, but the differences between file systems +> > are very small. +> +> Well, I only did a very rough benchmark (a few runs of pgbench), but +> the results I found were drastically different: ext2 was significantly +> faster (~50%) than ext3-writeback, which was in turn significantly +> faster (~25%) than ext3-ordered. + +Wow. That leaves no good Linux file system alternatives. PostgreSQL +just wants an ordinary file system that has reliable recovery from a +crash. + +> > Also, though ext3 is slower, turning fsync off should make ext3 function +> > similar to ext2. +> +> Why would that be? + +I assumed it was the double fsync for the normal and journal that made +the journalling file systems slog. + +-- + 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-hackers-owner@postgresql.org Thu Sep 26 16:50:43 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 59D4D476083 + for ; + Thu, 26 Sep 2002 16:50:42 -0400 (EDT) +Received: from bachata.cybertec.at (unknown [62.116.21.146]) + by postgresql.org (Postfix) with SMTP id 1856E474E5C + for ; + Thu, 26 Sep 2002 16:50:41 -0400 (EDT) +Received: (qmail 26347 invoked from network); 26 Sep 2002 20:50:47 -0000 +Received: from unknown (HELO cybertec.at) (62.116.21.147) + by 62.116.21.146 with SMTP; 26 Sep 2002 20:50:47 -0000 +Message-ID: <3D937442.40902@cybertec.at> +Date: Thu, 26 Sep 2002 22:55:30 +0200 +From: =?ISO-8859-1?Q?Hans-J=FCrgen_Sch=F6nig?= +Reply-To: hs@cybertec.at +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.1) Gecko/20020827 +X-Accept-Language: en-us, en +MIME-Version: 1.0 +To: Neil Conway , pgsql-hackers@postgresql.org +Subject: Re: [GENERAL] Performance while loading data and indexing +References: <200209261641.g8QGfYc04099@candle.pha.pa.us> + <871y7g1o1e.fsf@mailbox.samurai.com> +Content-Type: text/plain; charset=ISO-8859-1; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1576 +X-Sequence-Number: 29533 + +I have seen various benchmarks where XFS seems to perform best when it +comes to huge amounts of data and many files (due to balanced internal +b+ trees). +also, XFS seems to be VERY mature and very stable. +ext2/3 don't seem to be that fast in most of the benchmarks. + +i did some testing with reiser some time ago. the problem is that it +seems to restore a very historic consistent snapshot of the data. XFS +seems to be much better in this respect. + +i have not tested JFS yet (but on this damn AIX beside me) +from my point of view i strongly recommend XFS (maybe somebody from +RedHat should think about it). + + Hans + + +Neil Conway wrote: + +>Bruce Momjian writes: +> +> +>>The paper does recommend ext3, but the differences between file systems +>>are very small. +>> +>> +> +>Well, I only did a very rough benchmark (a few runs of pgbench), but +>the results I found were drastically different: ext2 was significantly +>faster (~50%) than ext3-writeback, which was in turn significantly +>faster (~25%) than ext3-ordered. +> +> +> +>>Also, though ext3 is slower, turning fsync off should make ext3 function +>>similar to ext2. +>> +>> +> +>Why would that be? +> +>Cheers, +> +>Neil +> +> +> + + +-- +*Cybertec Geschwinde u Schoenig* +Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria +Tel: +43/1/913 68 09; +43/664/233 90 75 +www.postgresql.at , cluster.postgresql.at +, www.cybertec.at +, kernel.cybertec.at + + +From pgsql-general-owner@postgresql.org Thu Sep 26 16:57:22 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id D2740476F59; Thu, 26 Sep 2002 16:57:21 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id AF1B947702E; Thu, 26 Sep 2002 16:57:14 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QKv3Z22867; + Thu, 26 Sep 2002 16:57:03 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262057.g8QKv3Z22867@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <871y7g1o1e.fsf@mailbox.samurai.com> +To: Neil Conway +Date: Thu, 26 Sep 2002 16:57:03 -0400 (EDT) +Cc: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1215 +X-Sequence-Number: 30796 + +Neil Conway wrote: +> Bruce Momjian writes: +> > The paper does recommend ext3, but the differences between file systems +> > are very small. +> +> Well, I only did a very rough benchmark (a few runs of pgbench), but +> the results I found were drastically different: ext2 was significantly +> faster (~50%) than ext3-writeback, which was in turn significantly +> faster (~25%) than ext3-ordered. +> +> > Also, though ext3 is slower, turning fsync off should make ext3 function +> > similar to ext2. +> +> Why would that be? + +OK, I changed the text to: + + 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. + +-- + 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-general-owner@postgresql.org Thu Sep 26 17:03:41 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 8D545476FB9; Thu, 26 Sep 2002 17:03:40 -0400 (EDT) +Received: from bob.samurai.com (bob.samurai.com [205.207.28.75]) + by postgresql.org (Postfix) with ESMTP + id 1A27A476F86; Thu, 26 Sep 2002 17:03:40 -0400 (EDT) +Received: from boston.samurai.com (DU179.N224.ResNet.QueensU.CA + [130.15.224.179]) by bob.samurai.com (Postfix) with ESMTP + id 0015F1EAB; Thu, 26 Sep 2002 17:03:39 -0400 (EDT) +To: Bruce Momjian +Cc: Neil Conway , + shridhar_daithankar@persistent.co.in, pgsql-hackers@postgresql.org, + pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> +From: Neil Conway +In-Reply-To: <200209262045.g8QKjtv21744@candle.pha.pa.us> +Date: 26 Sep 2002 17:03:26 -0400 +Message-ID: <87vg4szco1.fsf@mailbox.samurai.com> +Lines: 29 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1217 +X-Sequence-Number: 30798 + +Bruce Momjian writes: +> Wow. That leaves no good Linux file system alternatives. +> PostgreSQL just wants an ordinary file system that has reliable +> recovery from a crash. + +I'm not really familiar with the reasoning behind ext2's reputation as +recovering poorly from crashes; if we fsync a WAL record to disk +before we lose power, can't we recover reliably, even with ext2? + +> > > Also, though ext3 is slower, turning fsync off should make ext3 +> > > function similar to ext2. +> > +> > Why would that be? +> +> I assumed it was the double fsync for the normal and journal that +> made the journalling file systems slog. + +Well, a journalling file system would need to write a journal entry +and flush that to disk, even if fsync is disabled -- whereas without +fsync enabled, ext2 doesn't have to flush anything to disk. ISTM that +the performance advantage of ext2 over ext3 is should be even larger +when fsync is not enabled. + +Cheers, + +Neil + +-- +Neil Conway || PGP Key ID: DB3C29FC + + +From pgsql-hackers-owner@postgresql.org Thu Sep 26 17:04:07 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CF22C477069 + for ; + Thu, 26 Sep 2002 17:04:06 -0400 (EDT) +Received: from CopelandConsulting.Net (dsl-24293-ld.customer.centurytel.net + [209.142.135.135]) + by postgresql.org (Postfix) with ESMTP id 9BEAA476C0B + for ; + Thu, 26 Sep 2002 17:03:54 -0400 (EDT) +Received: from mouse.copelandconsulting.net (mouse.copelandconsulting.net + [192.168.1.2]) + by CopelandConsulting.Net (8.10.1/8.10.1) with ESMTP id g8QL3hu15120; + Thu, 26 Sep 2002 16:03:44 -0500 (CDT) +X-Trade-Id: +To: hs@cybertec.at +Cc: PostgresSQL Hackers Mailing List +In-Reply-To: <3D937442.40902@cybertec.at> +References: <200209261641.g8QGfYc04099@candle.pha.pa.us> + <871y7g1o1e.fsf@mailbox.samurai.com> <3D937442.40902@cybertec.at> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-ZqXCINKzOxv8OZvLp8ID" +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 16:03:51 -0500 +Message-Id: <1033074232.23474.42.camel@mouse.copelandconsulting.net> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1582 +X-Sequence-Number: 29539 + +--=-ZqXCINKzOxv8OZvLp8ID +Content-Type: text/plain; charset=ISO-8859-1 +Content-Transfer-Encoding: quoted-printable + +I tend to agree with this though I have nothing to back up it with. My +impression is that XFS does very well for large files. Accepting that +as fact?, my impression is that XFS historically does well for +database's. Again, I have nothing to back that up other than hear-say +and conjecture. + +Greg + + +On Thu, 2002-09-26 at 15:55, Hans-J=FCrgen Sch=F6nig wrote: +> I have seen various benchmarks where XFS seems to perform best when it=20 +> comes to huge amounts of data and many files (due to balanced internal=20 +> b+ trees). +> also, XFS seems to be VERY mature and very stable. +> ext2/3 don't seem to be that fast in most of the benchmarks. +>=20 +> i did some testing with reiser some time ago. the problem is that it=20 +> seems to restore a very historic consistent snapshot of the data. XFS=20 +> seems to be much better in this respect. +>=20 +> i have not tested JFS yet (but on this damn AIX beside me) +> from my point of view i strongly recommend XFS (maybe somebody from=20 +> RedHat should think about it). +>=20 +> Hans +>=20 +>=20 +> Neil Conway wrote: +>=20 +> >Bruce Momjian writes: +> >=20=20 +> > +> >>The paper does recommend ext3, but the differences between file systems +> >>are very small. +> >>=20=20=20=20 +> >> +> > +> >Well, I only did a very rough benchmark (a few runs of pgbench), but +> >the results I found were drastically different: ext2 was significantly +> >faster (~50%) than ext3-writeback, which was in turn significantly +> >faster (~25%) than ext3-ordered. +> > +> >=20=20 +> > +> >>Also, though ext3 is slower, turning fsync off should make ext3 function +> >>similar to ext2. +> >>=20=20=20=20 +> >> +> > +> >Why would that be? +> > +> >Cheers, +> > +> >Neil +> > +> >=20=20 +> > +>=20 +>=20 +> --=20 +> *Cybertec Geschwinde u Schoenig* +> Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria +> Tel: +43/1/913 68 09; +43/664/233 90 75 +> www.postgresql.at , cluster.postgresql.at=20 +> , www.cybertec.at=20 +> , kernel.cybertec.at +>=20 +>=20 +> ---------------------------(end of broadcast)--------------------------- +> TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org + + +--=-ZqXCINKzOxv8OZvLp8ID +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) + +iD8DBQA9k3Y34lr1bpbcL6kRAlvSAJ9DicilkkEypigomt/wfiO5nHyqqQCeOTHL +krIfkgUxrfgr50wh8oI93Lc= +=pUiE +-----END PGP SIGNATURE----- + +--=-ZqXCINKzOxv8OZvLp8ID-- + + +From pgsql-hackers-owner@postgresql.org Sat Sep 28 13:29:40 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id A7844476EEB; Thu, 26 Sep 2002 17:01:28 -0400 (EDT) +Received: from gatekeeper.d2000.com (gatekeeper.d2000.com [208.32.117.78]) + by postgresql.org (Postfix) with ESMTP + id AE297476E66; Thu, 26 Sep 2002 17:01:27 -0400 (EDT) +Received: (from bin@localhost) by gatekeeper.d2000.com (8.9.3/8.7.3) id + QAA41714; Thu, 26 Sep 2002 16:01:19 -0500 (CDT) +X-Authentication-Warning: gatekeeper.d2000.com: bin set sender to + using -f +Received: from (nt.d2000.com [205.164.66.20]) by + gatekeeper.d2000.com via smap (V2.1) + id xma041690; Thu, 26 Sep 02 16:00:47 -0500 +Received: from xl.d2000.com (unverified) by nt.d2000.com + (Content Technologies SMTPRS 4.1.5) with ESMTP id + ; + Thu, 26 Sep 2002 16:00:45 -0500 +Received: from materialpcow5r (backup.d2000.com [205.164.66.13]) by + xl.d2000.com (8.8.8/8.7.3) with SMTP id QAA05701; + Thu, 26 Sep 2002 16:00:33 -0500 (CDT) +From: "James Maes" +To: "Bruce Momjian" , + "Neil Conway" +Cc: , + , +Subject: Re: [GENERAL] Performance while loading data and indexing +Date: Thu, 26 Sep 2002 16:06:07 -0500 +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) +X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 +Importance: Normal +In-Reply-To: <200209262057.g8QKv3Z22867@candle.pha.pa.us> +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1669 +X-Sequence-Number: 29626 + +Has there been any thought of providing RAW disk support to bypass the fs? + +-----Original Message----- +From: pgsql-hackers-owner@postgresql.org +[mailto:pgsql-hackers-owner@postgresql.org]On Behalf Of Bruce Momjian +Sent: Thursday, September 26, 2002 3:57 PM +To: Neil Conway +Cc: shridhar_daithankar@persistent.co.in; pgsql-hackers@postgresql.org; +pgsql-general@postgresql.org +Subject: Re: [HACKERS] [GENERAL] Performance while loading data and +indexing + + +Neil Conway wrote: +> Bruce Momjian writes: +> > The paper does recommend ext3, but the differences between file systems +> > are very small. +> +> Well, I only did a very rough benchmark (a few runs of pgbench), but +> the results I found were drastically different: ext2 was significantly +> faster (~50%) than ext3-writeback, which was in turn significantly +> faster (~25%) than ext3-ordered. +> +> > Also, though ext3 is slower, turning fsync off should make ext3 function +> > similar to ext2. +> +> Why would that be? + +OK, I changed the text to: + + 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. + +-- + 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 + +---------------------------(end of broadcast)--------------------------- +TIP 5: Have you checked our extensive FAQ? + +http://www.postgresql.org/users-lounge/docs/faq.html + + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:08:13 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 3B9ED4769E6; Thu, 26 Sep 2002 17:08:13 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id 2AD5C476241; Thu, 26 Sep 2002 17:08:11 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QL7vN25965; + Thu, 26 Sep 2002 17:07:57 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262107.g8QL7vN25965@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <87vg4szco1.fsf@mailbox.samurai.com> +To: Neil Conway +Date: Thu, 26 Sep 2002 17:07:57 -0400 (EDT) +Cc: shridhar_daithankar@persistent.co.in, + pgsql-hackers@postgresql.org, pgsql-general@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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1218 +X-Sequence-Number: 30799 + +Neil Conway wrote: +> Bruce Momjian writes: +> > Wow. That leaves no good Linux file system alternatives. +> > PostgreSQL just wants an ordinary file system that has reliable +> > recovery from a crash. +> +> I'm not really familiar with the reasoning behind ext2's reputation as +> recovering poorly from crashes; if we fsync a WAL record to disk +> before we lose power, can't we recover reliably, even with ext2? +> +> > > > Also, though ext3 is slower, turning fsync off should make ext3 +> > > > function similar to ext2. +> > > +> > > Why would that be? +> > +> > I assumed it was the double fsync for the normal and journal that +> > made the journalling file systems slog. +> +> Well, a journalling file system would need to write a journal entry +> and flush that to disk, even if fsync is disabled -- whereas without +> fsync enabled, ext2 doesn't have to flush anything to disk. ISTM that +> the performance advantage of ext2 over ext3 is should be even larger +> when fsync is not enabled. + +Yes, it is still double-writing. I just thought that if that wasn't +happening while the db was waiting for a commit that it wouldn't be too +bad. + +Is it just me or do all the Linux file systems seem like they are +lacking something when PostgreSQL is concerned? We just want a UFS-like +file system on Linux and no one has 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-general-owner@postgresql.org Thu Sep 26 17:09:32 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 4AD7A476FCC; Thu, 26 Sep 2002 17:09:31 -0400 (EDT) +Received: from CopelandConsulting.Net (dsl-24293-ld.customer.centurytel.net + [209.142.135.135]) by postgresql.org (Postfix) with ESMTP + id 22CE6476FC8; Thu, 26 Sep 2002 17:09:30 -0400 (EDT) +Received: from mouse.copelandconsulting.net (mouse.copelandconsulting.net + [192.168.1.2]) + by CopelandConsulting.Net (8.10.1/8.10.1) with ESMTP id g8QL97u03616; + Thu, 26 Sep 2002 16:09:07 -0500 (CDT) +X-Trade-Id: +To: Neil Conway +Cc: Bruce Momjian , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <87vg4szco1.fsf@mailbox.samurai.com> +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> + <87vg4szco1.fsf@mailbox.samurai.com> +Content-Type: multipart/signed; micalg=pgp-sha1; + protocol="application/pgp-signature"; + boundary="=-ukBN/VLqUCvLMvEd/iTv" +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 16:09:15 -0500 +Message-Id: <1033074555.23344.48.camel@mouse.copelandconsulting.net> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1219 +X-Sequence-Number: 30800 + +--=-ukBN/VLqUCvLMvEd/iTv +Content-Type: text/plain +Content-Transfer-Encoding: quoted-printable + +On Thu, 2002-09-26 at 16:03, Neil Conway wrote: +> Bruce Momjian writes: +> > Wow. That leaves no good Linux file system alternatives. +> > PostgreSQL just wants an ordinary file system that has reliable +> > recovery from a crash. +>=20 +> I'm not really familiar with the reasoning behind ext2's reputation as +> recovering poorly from crashes; if we fsync a WAL record to disk +> before we lose power, can't we recover reliably, even with ext2? + +Well, I have experienced data loss from ext2 before. Also, recovery +from crashes on large file systems take a very, very long time. I can't +imagine anyone running a production database on an ext2 file system +having 10's or even 100's of GB. Ouch. Recovery would take forever!=20 +Even recovery on small file systems (2-8G) can take extended periods of +time. Especially so on IDE systems. Even then manual intervention is +not uncommon. + +While I can't say that x, y or z is the best FS to use on Linux, I can +say that ext2 is probably an exceptionally poor choice from a +reliability and/or uptime perspective. + +Greg + + +--=-ukBN/VLqUCvLMvEd/iTv +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) + +iD8DBQA9k3d74lr1bpbcL6kRAttbAJ44dhAlrsYjtTfGuieCrbJBqLV7PwCfWElV +QDa/ABmzxCPU/REOuseR7bo= +=Sg1u +-----END PGP SIGNATURE----- + +--=-ukBN/VLqUCvLMvEd/iTv-- + + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:17:43 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 4E5B1474E5C; Thu, 26 Sep 2002 17:17:42 -0400 (EDT) +Received: from bob.samurai.com (bob.samurai.com [205.207.28.75]) + by postgresql.org (Postfix) with ESMTP + id 3C927476F34; Thu, 26 Sep 2002 17:17:41 -0400 (EDT) +Received: from boston.samurai.com (DU179.N224.ResNet.QueensU.CA + [130.15.224.179]) by bob.samurai.com (Postfix) with ESMTP + id 066721ECE; Thu, 26 Sep 2002 17:17:42 -0400 (EDT) +To: Greg Copeland +Cc: Neil Conway , Bruce Momjian , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> + <87vg4szco1.fsf@mailbox.samurai.com> + <1033074555.23344.48.camel@mouse.copelandconsulting.net> +From: Neil Conway +In-Reply-To: <1033074555.23344.48.camel@mouse.copelandconsulting.net> +Date: 26 Sep 2002 17:17:30 -0400 +Message-ID: <87n0q4zc0l.fsf@mailbox.samurai.com> +Lines: 24 +User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1220 +X-Sequence-Number: 30801 + +Greg Copeland writes: +> On Thu, 2002-09-26 at 16:03, Neil Conway wrote: +> > I'm not really familiar with the reasoning behind ext2's +> > reputation as recovering poorly from crashes; if we fsync a WAL +> > record to disk before we lose power, can't we recover reliably, +> > even with ext2? +> +> Well, I have experienced data loss from ext2 before. Also, recovery +> from crashes on large file systems take a very, very long time. + +Yes, but wouldn't you face exactly the same issues if you ran a +UFS-like filesystem in asynchronous mode? Albeit it's not the default, +but performance in synchronous mode is usually pretty poor. + +The fact that ext2 defaults to asynchronous mode and UFS (at least on +the BSDs) defaults to synchronous mode seems like a total non-issue to +me. Is there any more to the alleged difference in reliability? + +Cheers, + +Neil + +-- +Neil Conway || PGP Key ID: DB3C29FC + + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:32:17 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 938DE4769BA; Thu, 26 Sep 2002 17:32:15 -0400 (EDT) +Received: from varsoon.wireboard.com (www.wireboard.com [216.151.155.101]) + by postgresql.org (Postfix) with ESMTP + id 0DC964769AE; Thu, 26 Sep 2002 17:32:15 -0400 (EDT) +Received: from doug by varsoon.wireboard.com with local (Exim 3.35 #1) + id 17ugEl-0006nF-00; Thu, 26 Sep 2002 17:31:55 -0400 +To: Bruce Momjian +From: Doug McNaught +Cc: Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209262000.g8QK0mG10553@candle.pha.pa.us> +Date: 26 Sep 2002 17:31:55 -0400 +In-Reply-To: Bruce Momjian's message of "Thu, + 26 Sep 2002 16:00:48 -0400 (EDT)" +Message-ID: +Lines: 24 +User-Agent: Gnus/5.0806 (Gnus v5.8.6) Emacs/20.7 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1221 +X-Sequence-Number: 30802 + +Bruce Momjian writes: + +> Can anyone clarify if "data=writeback" is safe for PostgreSQL. +> Specifically, are the data files recovered properly or is this option +> only for a filesystem containing WAL? + +"data=writeback" means that no data is journaled, just metadata (which +is like XFS or Reiser). An fsync() call should still do what it +normally does, commit the writes to disk before returning. + +"data=journal" journals all data and is the slowest and safest. +"data=ordered" writes out data blocks before committing a journal +transaction, which is faster than full data journaling (since data +doesn't get written twice) and almost as safe. "data=writeback" is +noted to keep obsolete data in the case of some crashes (since the +data may not have been written yet) but a completed fsync() should +ensure that the data is valid. + +So I guess I'd probably use data=ordered for an all-on-one-fs +installation, and data=writeback for a WAL-only drive. + +Hope this helps... + +-Doug + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:32:39 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 9C0C4477044 + for ; + Thu, 26 Sep 2002 17:32:38 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 591CA476F89 + for ; + Thu, 26 Sep 2002 17:32:26 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.5/8.12.5) with ESMTP id g8QLW1hR012931; + Thu, 26 Sep 2002 17:32:01 -0400 (EDT) +To: Neil Conway +Cc: Bruce Momjian , + shridhar_daithankar@persistent.co.in, pgsql-hackers@postgresql.org, + pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +In-reply-to: <87vg4szco1.fsf@mailbox.samurai.com> +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> + <87vg4szco1.fsf@mailbox.samurai.com> +Comments: In-reply-to Neil Conway + message dated "26 Sep 2002 17:03:26 -0400" +Date: Thu, 26 Sep 2002 17:32:01 -0400 +Message-ID: <12930.1033075921@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1222 +X-Sequence-Number: 30803 + +Neil Conway writes: +> I'm not really familiar with the reasoning behind ext2's reputation as +> recovering poorly from crashes; if we fsync a WAL record to disk +> before we lose power, can't we recover reliably, even with ext2? + +Up to a point. We do assume that the filesystem won't lose checkpointed +(sync'd) writes to data files. To the extent that the filesystem is +vulnerable to corruption of its own metadata for a file (indirect blocks +or whatever ext2 uses), that's not a completely safe assumption. + +We'd be happiest with a filesystem that journals its own metadata and +not the user data in the file(s). I dunno if there are any. + +Hmm, maybe this is why Oracle likes doing their own filesystem on a raw +device... + + regards, tom lane + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:37:39 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id F267E476FCC; Thu, 26 Sep 2002 17:37:38 -0400 (EDT) +Received: from varsoon.wireboard.com (www.wireboard.com [216.151.155.101]) + by postgresql.org (Postfix) with ESMTP + id 1DF13476FC3; Thu, 26 Sep 2002 17:37:38 -0400 (EDT) +Received: from doug by varsoon.wireboard.com with local (Exim 3.35 #1) + id 17ugJq-0006nf-00; Thu, 26 Sep 2002 17:37:10 -0400 +To: Tom Lane +From: Doug McNaught +Cc: Neil Conway , Bruce Momjian , + shridhar_daithankar@persistent.co.in, pgsql-hackers@postgresql.org, + pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> + <87vg4szco1.fsf@mailbox.samurai.com> <12930.1033075921@sss.pgh.pa.us> +Date: 26 Sep 2002 17:37:10 -0400 +In-Reply-To: Tom Lane's message of "Thu, 26 Sep 2002 17:32:01 -0400" +Message-ID: +Lines: 8 +User-Agent: Gnus/5.0806 (Gnus v5.8.6) Emacs/20.7 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1223 +X-Sequence-Number: 30804 + +Tom Lane writes: + +> We'd be happiest with a filesystem that journals its own metadata and +> not the user data in the file(s). I dunno if there are any. + +ext3 with data=writeback? (See my previous message to Bruce). + +-Doug + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:39:35 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 0C3B54760BD; Thu, 26 Sep 2002 17:39:35 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id 7E8AC4770C8; Thu, 26 Sep 2002 17:39:31 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QLdEE08861; + Thu, 26 Sep 2002 17:39:14 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262139.g8QLdEE08861@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <87n0q4zc0l.fsf@mailbox.samurai.com> +To: Neil Conway +Date: Thu, 26 Sep 2002 17:39:14 -0400 (EDT) +Cc: Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1224 +X-Sequence-Number: 30805 + +Neil Conway wrote: +> Greg Copeland writes: +> > On Thu, 2002-09-26 at 16:03, Neil Conway wrote: +> > > I'm not really familiar with the reasoning behind ext2's +> > > reputation as recovering poorly from crashes; if we fsync a WAL +> > > record to disk before we lose power, can't we recover reliably, +> > > even with ext2? +> > +> > Well, I have experienced data loss from ext2 before. Also, recovery +> > from crashes on large file systems take a very, very long time. +> +> Yes, but wouldn't you face exactly the same issues if you ran a +> UFS-like filesystem in asynchronous mode? Albeit it's not the default, +> but performance in synchronous mode is usually pretty poor. + +Yes, before UFS had soft updates, the synchronous nature of UFS made it +slower than ext2, but now with soft updates, that performance difference +is gone so you have two files systems, ext2 and ufs, similar peformance, +but one is crash-safe and the other is not. + +And, when comparing the journalling file systems, you have UFS vs. +XFS/ext3/JFS/Reiser, and UFS is faster. The only thing the journalling +file system give you is more rapid reboot, but frankly, if your OS goes +down often enough so that is an issue, you have bigger problems than +fsync time. + +The big problem is that Linux went from non-crash safe right to +crash-safe and reboot quick. We need a middle ground, which is where +UFS/soft updates is. + +> The fact that ext2 defaults to asynchronous mode and UFS (at least on +> the BSDs) defaults to synchronous mode seems like a total non-issue to +> me. Is there any more to the alleged difference in reliability? + +The reliability problem isn't alleged. ext2 developers admits ext2 +isn't 100% crash-safe. They will say it is usually crash-safe, but that +isn't good enough for PostgreSQL. + +I wish I was wrong. + +-- + 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-general-owner@postgresql.org Thu Sep 26 17:42:05 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 969E9476FEF; Thu, 26 Sep 2002 17:42:02 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id 97422476FDB; Thu, 26 Sep 2002 17:42:00 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QLfMr09064; + Thu, 26 Sep 2002 17:41:22 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262141.g8QLfMr09064@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: +To: Doug McNaught +Date: Thu, 26 Sep 2002 17:41:22 -0400 (EDT) +Cc: Tom Lane , Neil Conway , + shridhar_daithankar@persistent.co.in, pgsql-hackers@postgresql.org, + pgsql-general@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-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1225 +X-Sequence-Number: 30806 + +Doug McNaught wrote: +> Tom Lane writes: +> +> > We'd be happiest with a filesystem that journals its own metadata and +> > not the user data in the file(s). I dunno if there are any. +> +> ext3 with data=writeback? (See my previous message to Bruce). + +OK, so that makes ext3 crash safe without lots of overhead? + +-- + 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-hackers-owner@postgresql.org Thu Sep 26 17:45:16 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 460CF477047; Thu, 26 Sep 2002 17:45:14 -0400 (EDT) +Received: from squire.barchord.com (squire.barchord.com [216.194.67.18]) + by postgresql.org (Postfix) with ESMTP + id CA66D477042; Thu, 26 Sep 2002 17:45:13 -0400 (EDT) +Received: from [192.168.1.253] + (CPE00508b028d7d-CM00803785c5e0.cpe.net.cable.rogers.com + [24.103.51.175]) by squire.barchord.com (Postfix) with ESMTP + id 454C542C; Thu, 26 Sep 2002 17:45:15 -0400 (EDT) +Subject: Re: [GENERAL] Performance while loading data and indexing +From: Rod Taylor +To: Bruce Momjian +Cc: Neil Conway , + Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <200209262139.g8QLdEE08861@candle.pha.pa.us> +References: <200209262139.g8QLdEE08861@candle.pha.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 17:45:23 -0400 +Message-Id: <1033076723.27772.4.camel@jester> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1598 +X-Sequence-Number: 29555 + +On Thu, 2002-09-26 at 17:39, Bruce Momjian wrote: +> Neil Conway wrote: +> > Greg Copeland writes: +> > > On Thu, 2002-09-26 at 16:03, Neil Conway wrote: +> > > > I'm not really familiar with the reasoning behind ext2's +> > > > reputation as recovering poorly from crashes; if we fsync a WAL +> > > > record to disk before we lose power, can't we recover reliably, +> > > > even with ext2? +> > > +> > > Well, I have experienced data loss from ext2 before. Also, recovery +> > > from crashes on large file systems take a very, very long time. +> > +> > Yes, but wouldn't you face exactly the same issues if you ran a +> > UFS-like filesystem in asynchronous mode? Albeit it's not the default, +> > but performance in synchronous mode is usually pretty poor. +> +> Yes, before UFS had soft updates, the synchronous nature of UFS made it +> slower than ext2, but now with soft updates, that performance difference +> is gone so you have two files systems, ext2 and ufs, similar peformance, +> but one is crash-safe and the other is not. + +Note entirely true. ufs is both crash-safe and quick-rebootable. You +do need to fsck at some point, but not prior to mounting it. Any +corrupt blocks are empty, and are easy to avoid. + +Someone just needs to implement a background fsck that will run on a +mounted filesystem. + +-- + Rod Taylor + + +From pgsql-general-owner@postgresql.org Thu Sep 26 17:48:03 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 42A774767DA; Thu, 26 Sep 2002 17:48:03 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id 5FC1E476212; Thu, 26 Sep 2002 17:48:01 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QLlhU10159; + Thu, 26 Sep 2002 17:47:43 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262147.g8QLlhU10159@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <1033076723.27772.4.camel@jester> +To: Rod Taylor +Date: Thu, 26 Sep 2002 17:47:43 -0400 (EDT) +Cc: Neil Conway , + Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1227 +X-Sequence-Number: 30808 + +Rod Taylor wrote: +> > Yes, before UFS had soft updates, the synchronous nature of UFS made it +> > slower than ext2, but now with soft updates, that performance difference +> > is gone so you have two files systems, ext2 and ufs, similar peformance, +> > but one is crash-safe and the other is not. +> +> Note entirely true. ufs is both crash-safe and quick-rebootable. You +> do need to fsck at some point, but not prior to mounting it. Any +> corrupt blocks are empty, and are easy to avoid. + +I am assuming you need to mount the drive as part of the reboot. Of +course you can boot fast with any file system if you don't have to mount +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-general-owner@postgresql.org Sat Sep 28 13:41:23 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 991FA47618E; Thu, 26 Sep 2002 18:03:27 -0400 (EDT) +Received: from squire.barchord.com (squire.barchord.com [216.194.67.18]) + by postgresql.org (Postfix) with ESMTP + id 221B74760B7; Thu, 26 Sep 2002 18:03:27 -0400 (EDT) +Received: from [192.168.1.253] + (CPE00508b028d7d-CM00803785c5e0.cpe.net.cable.rogers.com + [24.103.51.175]) by squire.barchord.com (Postfix) with ESMTP + id 8ECED42C; Thu, 26 Sep 2002 18:03:28 -0400 (EDT) +Subject: Re: [HACKERS] Performance while loading data and indexing +From: Rod Taylor +To: Bruce Momjian +Cc: Neil Conway , + Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +In-Reply-To: <200209262147.g8QLlhU10159@candle.pha.pa.us> +References: <200209262147.g8QLlhU10159@candle.pha.pa.us> +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.8 +Date: 26 Sep 2002 18:03:36 -0400 +Message-Id: <1033077816.27772.9.camel@jester> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1330 +X-Sequence-Number: 30911 + +On Thu, 2002-09-26 at 17:47, Bruce Momjian wrote: +> Rod Taylor wrote: +> > > Yes, before UFS had soft updates, the synchronous nature of UFS made it +> > > slower than ext2, but now with soft updates, that performance difference +> > > is gone so you have two files systems, ext2 and ufs, similar peformance, +> > > but one is crash-safe and the other is not. +> > +> > Note entirely true. ufs is both crash-safe and quick-rebootable. You +> > do need to fsck at some point, but not prior to mounting it. Any +> > corrupt blocks are empty, and are easy to avoid. +> +> I am assuming you need to mount the drive as part of the reboot. Of +> course you can boot fast with any file system if you don't have to mount +> it. :-) + +Sorry, poor explanation. + +Background fsck (when implemented) would operate on a currently mounted +(and active) file system. The only reason fsck is required prior to +reboot now is because no-one had done the work. + +http://www.freebsd.org/cgi/man.cgi?query=fsck&sektion=8&manpath=FreeBSD+5.0-current + +See the first paragraph of the above. +-- + Rod Taylor + + +From pgsql-general-owner@postgresql.org Thu Sep 26 18:05:13 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id C0E5F476FAF; Thu, 26 Sep 2002 18:05:12 -0400 (EDT) +Received: from candle.pha.pa.us (momjian.navpoint.com [207.106.42.251]) + by postgresql.org (Postfix) with ESMTP + id C71D6476F95; Thu, 26 Sep 2002 18:05:10 -0400 (EDT) +Received: (from pgman@localhost) + by candle.pha.pa.us (8.11.6/8.10.1) id g8QM4qX11641; + Thu, 26 Sep 2002 18:04:52 -0400 (EDT) +From: Bruce Momjian +Message-Id: <200209262204.g8QM4qX11641@candle.pha.pa.us> +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <1033077816.27772.9.camel@jester> +To: Rod Taylor +Date: Thu, 26 Sep 2002 18:04:52 -0400 (EDT) +Cc: Neil Conway , + Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +X-Mailer: ELM [version 2.4ME+ PL99 (25)] +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +Content-Type: text/plain; charset=US-ASCII +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1229 +X-Sequence-Number: 30810 + +Rod Taylor wrote: +> On Thu, 2002-09-26 at 17:47, Bruce Momjian wrote: +> > Rod Taylor wrote: +> > > > Yes, before UFS had soft updates, the synchronous nature of UFS made it +> > > > slower than ext2, but now with soft updates, that performance difference +> > > > is gone so you have two files systems, ext2 and ufs, similar peformance, +> > > > but one is crash-safe and the other is not. +> > > +> > > Note entirely true. ufs is both crash-safe and quick-rebootable. You +> > > do need to fsck at some point, but not prior to mounting it. Any +> > > corrupt blocks are empty, and are easy to avoid. +> > +> > I am assuming you need to mount the drive as part of the reboot. Of +> > course you can boot fast with any file system if you don't have to mount +> > it. :-) +> +> Sorry, poor explanation. +> +> Background fsck (when implemented) would operate on a currently mounted +> (and active) file system. The only reason fsck is required prior to +> reboot now is because no-one had done the work. +> +> http://www.freebsd.org/cgi/man.cgi?query=fsck&sektion=8&manpath=FreeBSD+5.0-current +> +> See the first paragraph of the above. + +Oh, yes, I have heard of that missing feature. + +-- + 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-general-owner@postgresql.org Thu Sep 26 19:26:22 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id 625C74763DD; Thu, 26 Sep 2002 19:26:21 -0400 (EDT) +Received: from varsoon.wireboard.com (www.wireboard.com [216.151.155.101]) + by postgresql.org (Postfix) with ESMTP + id C8EF147628D; Thu, 26 Sep 2002 19:26:20 -0400 (EDT) +Received: from doug by varsoon.wireboard.com with local (Exim 3.35 #1) + id 17ui1D-0006sX-00; Thu, 26 Sep 2002 19:26:03 -0400 +To: Bruce Momjian +From: Doug McNaught +Cc: Tom Lane , Neil Conway , + shridhar_daithankar@persistent.co.in, pgsql-hackers@postgresql.org, + pgsql-general@postgresql.org +Subject: Re: [HACKERS] Performance while loading data and indexing +References: <200209262141.g8QLfMr09064@candle.pha.pa.us> +Date: 26 Sep 2002 19:26:03 -0400 +In-Reply-To: Bruce Momjian's message of "Thu, + 26 Sep 2002 17:41:22 -0400 (EDT)" +Message-ID: +Lines: 23 +User-Agent: Gnus/5.0806 (Gnus v5.8.6) Emacs/20.7 +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1231 +X-Sequence-Number: 30812 + +Bruce Momjian writes: + +> Doug McNaught wrote: +> > Tom Lane writes: +> > +> > > We'd be happiest with a filesystem that journals its own metadata and +> > > not the user data in the file(s). I dunno if there are any. +> > +> > ext3 with data=writeback? (See my previous message to Bruce). +> +> OK, so that makes ext3 crash safe without lots of overhead? + +Metadata is journaled so you shouldn't lose data blocks or directory +entries. Some data blocks (that haven't been fsync()'ed) may have old +or wrong data in them, but I think that's the same as ufs, right? And +WAL replay should take care of that. + +It'd be very interesting to do some tests of the various journaling +modes. I have an old K6 that I might be able to turn into a +hit-the-reset-switch-at-ramdom-times machine. What kind of tests +should be run? + +-Doug + +From pgsql-performance-owner@postgresql.org Thu Sep 26 22:53:21 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 353A4476391 + for ; + Thu, 26 Sep 2002 22:53:21 -0400 (EDT) +Received: from corpmail.outblaze.com (202-77-223-51.outblaze.com + [202.77.223.51]) + by postgresql.org (Postfix) with ESMTP id D37A247632D + for ; + Thu, 26 Sep 2002 22:53:19 -0400 (EDT) +Received: from yusufg.portal2.com (202-77-223-2.outblaze.com [202.77.223.2]) + by corpmail.outblaze.com (8.12.6/8.12.6) with SMTP id g8R2rMm8029328 + for ; Fri, 27 Sep 2002 02:53:22 GMT +Received: (qmail 1463 invoked by uid 500); 27 Sep 2002 02:55:10 -0000 +Date: Fri, 27 Sep 2002 10:55:10 +0800 +From: Yusuf Goolamabbas +To: pgsql-performance@postgresql.org +Subject: Would ext3 data=journal help for Postgres synchronous io mode +Message-ID: <20020927025510.GB1175@outblaze.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.4i +X-AntiVirus: checked by Vexira Milter 1.0.0.3; VAE 6.15.0.1; VDF 6.15.0.9 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/14 +X-Sequence-Number: 14 + +According to ext3 hackers (Stephen Tweedie, Andrew Morton). ext3 +data=journal mode is much faster than any of the other mode for +workloads which do a lot of syncrhonous i/o. Personally, I have seen +dramatic improvements on moving mail queues to this mode (postfix in +particularly flies with this mode) + +While this may seem contradictory (forcing journaling for the data in +addition to the metadata), it will likely improve the performance for +sync I/O loads like mail servers because it can do all of the I/O to the +journal without any seek or sync overhead while the mail is arriving. + +I assume that since Postgresql does a lot of fsyncs, it would benefit +also. I have sent email to Sridhar asking if he could test this + +Another thing to note is that Linux 2.4.x kernels < 2.4.20-pre4 use +bounce buffer's to do IO if the machine has > 1GB memory. Distributor +kernels such as Redhat/Suse/Mandrake are patched to do IO via DMA +to/from highmem (>1GB). According to IBM's paper @ OLS, this improves IO +performance by 40% + +BTW, Is this list archived on the website + +Regards, Yusuf +-- +Yusuf Goolamabbas +yusufg@outblaze.com + +From pgsql-general-owner@postgresql.org Thu Sep 26 23:08:32 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 3C676477068 + for ; + Thu, 26 Sep 2002 23:08:30 -0400 (EDT) +Received: from sss.pgh.pa.us (unknown [192.204.191.242]) + by postgresql.org (Postfix) with ESMTP id 3674347703B + for ; + Thu, 26 Sep 2002 23:08:29 -0400 (EDT) +Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) + by sss.pgh.pa.us (8.12.5/8.12.5) with ESMTP id g8R37jhR020360; + Thu, 26 Sep 2002 23:07:45 -0400 (EDT) +To: Doug McNaught +Cc: Bruce Momjian , + Greg Copeland , + shridhar_daithankar@persistent.co.in, + PostgresSQL Hackers Mailing List , + PostgresSQL General Mailing List +Subject: Re: [HACKERS] Performance while loading data and indexing +In-reply-to: +References: <200209262000.g8QK0mG10553@candle.pha.pa.us> + +Comments: In-reply-to Doug McNaught + message dated "26 Sep 2002 17:31:55 -0400" +Date: Thu, 26 Sep 2002 23:07:44 -0400 +Message-ID: <20359.1033096064@sss.pgh.pa.us> +From: Tom Lane +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1242 +X-Sequence-Number: 30823 + +Doug McNaught writes: +> "data=writeback" means that no data is journaled, just metadata (which +> is like XFS or Reiser). An fsync() call should still do what it +> normally does, commit the writes to disk before returning. +> "data=journal" journals all data and is the slowest and safest. +> "data=ordered" writes out data blocks before committing a journal +> transaction, which is faster than full data journaling (since data +> doesn't get written twice) and almost as safe. "data=writeback" is +> noted to keep obsolete data in the case of some crashes (since the +> data may not have been written yet) but a completed fsync() should +> ensure that the data is valid. + +Thanks for the explanation. + +> So I guess I'd probably use data=ordered for an all-on-one-fs +> installation, and data=writeback for a WAL-only drive. + +Actually I think the ideal thing for Postgres would be data=writeback +for both data and WAL drives. We can handle loss of un-fsync'd data +for ourselves in both cases. + +Of course, if you keep anything besides Postgres data files on a +partition, you'd possibly want the more secure settings. + + regards, tom lane + +From pgsql-general-owner@postgresql.org Fri Sep 27 01:12:31 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP + id D61BE47714E; Fri, 27 Sep 2002 01:12:30 -0400 (EDT) +Received: from panda.center-f1.ru (panda.center-f1.ru [195.151.30.15]) + by postgresql.org (Postfix) with ESMTP + id C4927477196; Fri, 27 Sep 2002 01:12:28 -0400 (EDT) +Received: from localhost (byg@localhost) + by panda.center-f1.ru (8.11.6/8.11.6) with ESMTP id g8R5Ee308324; + Fri, 27 Sep 2002 12:14:40 +0700 +X-Authentication-Warning: panda.center-f1.ru: byg owned process doing -bs +Date: Fri, 27 Sep 2002 12:14:40 +0700 (NOVST) +From: Yury Bokhoncovich +To: Bruce Momjian +Cc: Neil Conway , , + , +Subject: Re: [HACKERS] Performance while loading data and indexing +In-Reply-To: <200209262107.g8QL7vN25965@candle.pha.pa.us> +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1253 +X-Sequence-Number: 30834 + +Hello! + +On Thu, 26 Sep 2002, Bruce Momjian wrote: + +> > I'm not really familiar with the reasoning behind ext2's reputation as +> > recovering poorly from crashes; if we fsync a WAL record to disk + +On relatively big volumes ext2 recovery can end up in formatting the fs +under certain cirrumstances.;-) + +> > > I assumed it was the double fsync for the normal and journal that +> > > made the journalling file systems slog. +> > +> > Well, a journalling file system would need to write a journal entry +> > and flush that to disk, even if fsync is disabled -- whereas without +> > fsync enabled, ext2 doesn't have to flush anything to disk. ISTM that +> > the performance advantage of ext2 over ext3 is should be even larger +> > when fsync is not enabled. +> +> Yes, it is still double-writing. I just thought that if that wasn't +> happening while the db was waiting for a commit that it wouldn't be too +> bad. +> +> Is it just me or do all the Linux file systems seem like they are +> lacking something when PostgreSQL is concerned? We just want a UFS-like +> file system on Linux and no one has it. + +mount -o sync an ext2 volume on Linux - and you can get a "UFS-like" fs.:) +mount -o async an FFS volume on FreeBSD - and you can get boost in fs +performance. +Personally me always mount ext2 fs where Pg is living with sync option. +Fsync in pg is off (since 6.3), this way successfully pass thru a few +serious crashes on various systems (mostly on power problems). +If fsync is on in Pg, performance gets so-oh-oh-oh-oh slowly!=) +I just have done upgrade from 2.2 kernel on ext2 to ext3 capable 2.4 one +so I'm planning to do some benchmarking. Roughly saying w/o benchmarks, +the performance have been degraded in 2/3 proportion. +"But better safe then sorry". + +-- +WBR, Yury Bokhoncovich, Senior System Administrator, NOC of F1 Group. +Phone: +7 (3832) 106228, ext.140, E-mail: byg@center-f1.ru. +Unix is like a wigwam -- no Gates, no Windows, and an Apache inside. + + + +From pgsql-performance-owner@postgresql.org Fri Sep 27 05:42:31 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 95321475EDF + for ; + Fri, 27 Sep 2002 05:42:26 -0400 (EDT) +Received: from freemail.agrinet.ch (freemail.agrinet.ch [212.28.134.90]) + by postgresql.org (Postfix) with ESMTP id 267654771AE + for ; + Fri, 27 Sep 2002 05:42:23 -0400 (EDT) +Received: from syydelaervli.fortytwo.ch (81.6.8.94) by freemail.agrinet.ch + (NPlex 5.1.056) + id 3D921E0A00007388 for pgsql-performance@postgresql.org; + Fri, 27 Sep 2002 11:42:24 +0200 +Received: from atlas.acter.ch (unknown [212.126.160.108]) + by syydelaervli.fortytwo.ch (Postfix) with ESMTP id 43EF52A76 + for ; + Fri, 27 Sep 2002 11:42:23 +0200 (CEST) +Received: by atlas.acter.ch (Postfix, from userid 1047) + id 7B2A89696; Fri, 27 Sep 2002 11:42:22 +0200 (CEST) +Subject: +From: Adrian von Bidder +To: PostgreSQL Performance Mailing List +Content-Type: text/plain +Content-Transfer-Encoding: 7bit +X-Mailer: Ximian Evolution 1.0.8 +Date: 27 Sep 2002 11:42:22 +0200 +Message-Id: <1033119742.13843.9.camel@atlas> +Mime-Version: 1.0 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/15 +X-Sequence-Number: 15 + +subscribe +-- +secure email with gpg http://fortytwo.ch/gpg + +NOTICE: subkey signature! request key 92082481 from keyserver.kjsl.com + +From pgsql-general-owner@postgresql.org Fri Sep 27 06:40:18 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 883AA475D00 + for ; + Fri, 27 Sep 2002 06:40:17 -0400 (EDT) +Received: from news.hub.org (news.hub.org [64.49.215.80]) + by postgresql.org (Postfix) with ESMTP id 3C44B475EC7 + for ; + Fri, 27 Sep 2002 06:40:16 -0400 (EDT) +Received: by news.hub.org (Postfix, from userid 8) + id 5AC2C381683; Fri, 27 Sep 2002 06:40:15 -0400 (EDT) +From: Mats Lofkvist +X-Newsgroups: comp.databases.postgresql.general, + comp.databases.postgresql.questions +Subject: Re: [HACKERS] Performance while loading data and indexing +Date: 27 Sep 2002 12:40:13 +0200 +Organization: Hub.Org Networking Services (http://www.hub.org) +Lines: 29 +Message-ID: +References: <87n0q4zc0l.fsf@mailbox.samurai.com> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Complaints-To: news@hub.org +User-Agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.5 +To: pgsql-general@postgresql.org +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1268 +X-Sequence-Number: 30849 + +neilc@samurai.com (Neil Conway) writes: + +[snip] +> > Well, I have experienced data loss from ext2 before. Also, recovery +> > from crashes on large file systems take a very, very long time. +> +> Yes, but wouldn't you face exactly the same issues if you ran a +> UFS-like filesystem in asynchronous mode? Albeit it's not the default, +> but performance in synchronous mode is usually pretty poor. +> +> The fact that ext2 defaults to asynchronous mode and UFS (at least on +> the BSDs) defaults to synchronous mode seems like a total non-issue to +> me. Is there any more to the alleged difference in reliability? + +UFS on most unix systems (BSD, solaris etc) defaults to sync +metadata, async data which is a mode that is completely missing +from ext2 as far as I know. + +This is why UFS is considered safer than ext2. (Running with +'sync' is too slow to be a usable alternative in most cases.) + + _ +Mats Lofkvist +mal@algonet.se + + +PS The BSD soft updates yields the safety of the default sync + metadata / async data mode while being at least as fast as + running fully async. + +From pgsql-general-owner@postgresql.org Fri Sep 27 06:49:23 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CD832476243 + for ; + Fri, 27 Sep 2002 06:49:21 -0400 (EDT) +Received: from news.hub.org (news.hub.org [64.49.215.80]) + by postgresql.org (Postfix) with ESMTP id 69480476160 + for ; + Fri, 27 Sep 2002 06:49:21 -0400 (EDT) +Received: by news.hub.org (Postfix, from userid 8) + id 68B29381683; Fri, 27 Sep 2002 06:49:18 -0400 (EDT) +From: Mats Lofkvist +X-Newsgroups: comp.databases.postgresql.general, + comp.databases.postgresql.questions +Subject: Re: Performance while loading data and indexing +Date: 27 Sep 2002 12:49:17 +0200 +Organization: Hub.Org Networking Services (http://www.hub.org) +Lines: 21 +Message-ID: +References: <3D931438.22010.133ADAFA@localhost> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Complaints-To: news@hub.org +User-Agent: Gnus/5.0803 (Gnus v5.8.3) Emacs/20.5 +To: pgsql-general@postgresql.org +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1269 +X-Sequence-Number: 30850 + +shridhar_daithankar@persistent.co.in ("Shridhar Daithankar") writes: + +[snip] +> +> Couple MB of data per sec. to disk is just not saturating it. It's a RAID 5 +> setup.. +> + +RAID5 is not the best for performance, especially write performance. +If it is software RAID it is even worse :-). + +(Note also that you need to check that you are not saturating the +number of seeks the disks can handle, not just the bandwith.) + +Striping should be better (combined with mirroring if you need the +safety, but with both striping and mirroring you may need multiple +SCSI channels). + + _ +Mats Lofkvist +mal@algonet.se + +From pgsql-general-owner@postgresql.org Fri Sep 27 11:20:38 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 99F9947608D + for ; + Fri, 27 Sep 2002 11:20:36 -0400 (EDT) +Received: from mail1.ihs.com (mail1.ihs.com [170.207.70.222]) + by postgresql.org (Postfix) with ESMTP id BAD85475FEB + for ; + Fri, 27 Sep 2002 11:20:35 -0400 (EDT) +Received: from css120.ihs.com (css120.ihs.com [170.207.105.120]) + by mail1.ihs.com (8.12.6/8.12.6) with ESMTP id g8RFJikY015704; + Fri, 27 Sep 2002 09:19:45 -0600 (MDT) +Date: Fri, 27 Sep 2002 09:16:03 -0600 (MDT) +From: "scott.marlowe" +To: Mats Lofkvist +Cc: +Subject: Re: Performance while loading data and indexing +In-Reply-To: +Message-ID: +MIME-Version: 1.0 +Content-Type: TEXT/PLAIN; charset=US-ASCII +X-MailBodyFilter: Message body has not been filtered +X-MailScanner: Found to be clean +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1280 +X-Sequence-Number: 30861 + +On 27 Sep 2002, Mats Lofkvist wrote: + +> shridhar_daithankar@persistent.co.in ("Shridhar Daithankar") writes: +> +> [snip] +> > +> > Couple MB of data per sec. to disk is just not saturating it. It's a RAID 5 +> > setup.. +> > +> +> RAID5 is not the best for performance, especially write performance. +> If it is software RAID it is even worse :-). + +I take exception to this. RAID5 is a great choice for most folks. + +1: RAID5 only writes out the parity stripe and data stripe, not all +stripes when writing. So, in an 8 disk RAID5 array, writing to a single +64 k stripe involves one 64k read (parity stripe) and two 64k writes. + +On a mirror set, writing to one 64k stripe involves two 64k writes. The +difference isn't that great, and in my testing, a large enough RAID5 +provides so much faster read speads by spreading the reads across so many +heads as to more than make up for the slightly slower writes. My testing +has shown that a 4 disk RAID5 can generally run about 85% or more the +speed of a mirror set. + +2: Why does EVERYONE have to jump on the bandwagon that software RAID 5 +is bad. My workstation running RH 7.2 uses about 1% of the CPU during +very heavy parallel access (i.e. 50 simo pgbenchs) at most. I've seen +many hardware RAID cards that are noticeable slower than my workstation +running software RAID. You do know that hardware RAID is just software +RAID where the processing is done on a seperate CPU on a card, but it's +still software doing the work. + +3: We just had a hardware RAID card mark both drives in a mirror set bad. +It wouldn't accept them back, and all the data was gone. poof. That +would never happen in Linux's kernel software RAID, I can always make +Linux take back a "bad" drive. + + +The only difference between RAID5 with n+1 disks and RAID0 with n disks is +that we have to write a parity stripe in RAID5. It's ability to handle +high parallel load is much better than a RAID1 set, and on average, you +actually write about the same amount with either RAID1 or RAID5. + +Don't dog software RAID5, it works and it works well in Linux. Windows, +however, is another issue. There, the software RAID5 is pretty pitiful, +both in terms of performance and maintenance. + + +From pgsql-hackers-owner@postgresql.org Fri Sep 27 15:01:43 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 976E6476D74 + for ; + Fri, 27 Sep 2002 15:01:42 -0400 (EDT) +Received: from Mail.CERT.Uni-Stuttgart.DE (mail.cert.uni-stuttgart.de + [129.69.16.17]) by postgresql.org (Postfix) with ESMTP id 3F3234761C2 + for ; + Fri, 27 Sep 2002 15:01:38 -0400 (EDT) +Received: from rusfw by Mail.CERT.Uni-Stuttgart.DE with local (Exim 4.04) + id 17v0Ms-0006Sx-00 + for pgsql-hackers@postgresql.org; Fri, 27 Sep 2002 21:01:38 +0200 +To: pgsql-hackers@postgresql.org +Subject: Re: [GENERAL] Performance while loading data and indexing +References: <200209262045.g8QKjtv21744@candle.pha.pa.us> + <87vg4szco1.fsf@mailbox.samurai.com> <12930.1033075921@sss.pgh.pa.us> +Mail-Followup-To: pgsql-hackers@postgresql.org +From: Florian Weimer +Date: Fri, 27 Sep 2002 21:01:38 +0200 +In-Reply-To: <12930.1033075921@sss.pgh.pa.us> (Tom Lane's message of "Thu, + 26 Sep 2002 17:32:01 -0400") +Message-ID: <87hegbjlyl.fsf@Login.CERT.Uni-Stuttgart.DE> +Lines: 12 +User-Agent: Gnus/5.090007 (Oort Gnus v0.07) Emacs/21.2 (i386-debian-linux-gnu) +MIME-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1630 +X-Sequence-Number: 29587 + +Tom Lane writes: + +> We'd be happiest with a filesystem that journals its own metadata and +> not the user data in the file(s). I dunno if there are any. + +Most journalling file systems work this way. Data journalling is not +very widespread, AFAIK. + +-- +Florian Weimer Weimer@CERT.Uni-Stuttgart.DE +University of Stuttgart http://CERT.Uni-Stuttgart.DE/people/fw/ +RUS-CERT fax +49-711-685-5898 + +From pgsql-general-owner@postgresql.org Fri Sep 27 21:46:57 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id CBFF34762B5 + for ; + Fri, 27 Sep 2002 21:46:55 -0400 (EDT) +Received: from deborah.paradise.net.nz (deborah.paradise.net.nz + [203.96.152.32]) + by postgresql.org (Postfix) with ESMTP id 107AB47626D + for ; + Fri, 27 Sep 2002 21:46:55 -0400 (EDT) +Received: from paradise.net.nz (203-79-74-52.adsl.paradise.net.nz + [203.79.74.52]) by deborah.paradise.net.nz (Postfix) with ESMTP + id 73EE1D1CAF; Sat, 28 Sep 2002 13:46:48 +1200 (NZST) +Message-ID: <3D95082C.4070904@paradise.net.nz> +Date: Sat, 28 Sep 2002 13:38:52 +1200 +From: Mark Kirkwood +User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8) Gecko/20020204 +X-Accept-Language: en-us +MIME-Version: 1.0 +To: "scott.marlowe" +Cc: Mats Lofkvist , pgsql-general@postgresql.org +Subject: Re: Performance while loading data and indexing +References: +Content-Type: text/plain; charset=us-ascii; format=flowed +Content-Transfer-Encoding: 7bit +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/1319 +X-Sequence-Number: 30900 + +scott.marlowe wrote: + +>(snippage) +>I take exception to this. RAID5 is a great choice for most folks. +> +> +I agree - certainly RAID5 *used* to be rather sad, but modern cards have +improved this no end on the hardware side - e.g. + +I recently benchmarked a 3Ware 8x card on a system with 4 x 15000 rpm +Maxtor 70Gb drives and achieved 120 Mb/s for (8K) reads and 60 Mb/s for +(8K) writes using RAID5. I used Redhat 7.3 + ext2. The benchmarking +program was Bonnie. + +Given that the performance of a single disk was ~30 Mb/s for reads and +writes, I felt this was quite a good result ! ( Other cards I had tried +previously struggled to maintain 1/2 the write rate of a single disk in +such a configuration). + +As for software RAID5, I have not tried it out. + +Of course I could not get 60Mb/s while COPYing data into Postgres... +typically cpu seemed to be the bottleneck in this case (what was the +actual write rate? I hear you asking..err.. cant recall I'm afraid.. +must try it out again ) + +cheers + +Mark + + +From pgsql-performance-owner@postgresql.org Sat Sep 28 11:49:21 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 7544B475E26 + for ; + Sat, 28 Sep 2002 11:49:20 -0400 (EDT) +Received: from kumudu.nslk.com (kumudu.nslk.com [64.247.55.254]) + by postgresql.org (Postfix) with ESMTP id 01B30475E25 + for ; + Sat, 28 Sep 2002 11:49:20 -0400 (EDT) +Received: from [203.94.93.204] (helo=W) + by kumudu.nslk.com with asmtp (Exim 3.36 #1) id 17vJqE-00034v-00 + for pgsql-performance@postgresql.org; Sat, 28 Sep 2002 11:49:15 -0400 +Message-ID: <010801c26706$be9e3820$cc5d5ecb@A.GEEKIYANAGE> +Reply-To: "Waruna Geekiyanage" +From: "Waruna Geekiyanage" +To: +Subject: INDEX +Date: Sat, 28 Sep 2002 21:50:13 +0600 +MIME-Version: 1.0 +Content-Type: multipart/alternative; + boundary="----=_NextPart_000_0105_01C26739.06687120" +X-Priority: 3 +X-MSMail-Priority: Normal +X-Mailer: Microsoft Outlook Express 5.00.2919.6600 +X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 +X-AntiAbuse: This header was added to track abuse, + please include it with any abuse report +X-AntiAbuse: Primary Hostname - kumudu.nslk.com +X-AntiAbuse: Original Domain - postgresql.org +X-AntiAbuse: Originator/Caller UID/GID - [0 0] / [0 0] +X-AntiAbuse: Sender Address Domain - nirmani.com +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/16 +X-Sequence-Number: 16 + +This is a multi-part message in MIME format. + +------=_NextPart_000_0105_01C26739.06687120 +Content-Type: text/plain; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable + +When a table is created with a primary key it generates a index. +Dos the queries on that table use that index automatically? +Do I need to reindex that index after insertions? + +------=_NextPart_000_0105_01C26739.06687120 +Content-Type: text/html; + charset="iso-8859-1" +Content-Transfer-Encoding: quoted-printable + + + + + + + + +
When a table is created with a primary key= + it=20 +generates a index.
+
Dos the queries on that table use that ind= +ex=20 +automatically?
+
Do I need to reindex that index after=20 +insertions?
+ +------=_NextPart_000_0105_01C26739.06687120-- + + +From pgsql-performance-owner@postgresql.org Sat Sep 28 15:13:19 2002 +Received: from localhost (postgresql.org [64.49.215.8]) + by postgresql.org (Postfix) with ESMTP id 5E9C84762E3 + for ; + Sat, 28 Sep 2002 15:13:18 -0400 (EDT) +Received: from mail.libertyrms.com (unknown [209.167.124.227]) + by postgresql.org (Postfix) with ESMTP id B81B647612B + for ; + Sat, 28 Sep 2002 15:13:17 -0400 (EDT) +Received: from andrew by mail.libertyrms.com with local (Exim 3.22 #3 + (Debian)) + id 17vN1i-00065x-00 + for ; Sat, 28 Sep 2002 15:13:18 -0400 +Date: Sat, 28 Sep 2002 15:13:18 -0400 +From: Andrew Sullivan +To: pgsql-performance@postgresql.org +Subject: Re: INDEX +Message-ID: <20020928151318.B22793@mail.libertyrms.com> +Mail-Followup-To: pgsql-performance@postgresql.org +References: <010801c26706$be9e3820$cc5d5ecb@A.GEEKIYANAGE> +Mime-Version: 1.0 +Content-Type: text/plain; charset=us-ascii +Content-Disposition: inline +User-Agent: Mutt/1.2.5i +In-Reply-To: <010801c26706$be9e3820$cc5d5ecb@A.GEEKIYANAGE>; + from waruna@nirmani.com on Sat, Sep 28, 2002 at 09:50:13PM +0600 +X-Virus-Scanned: by AMaViS new-20020517 +X-Archive-Number: 200209/17 +X-Sequence-Number: 17 + +On Sat, Sep 28, 2002 at 09:50:13PM +0600, Waruna Geekiyanage wrote: +> When a table is created with a primary key it generates a index. +> Dos the queries on that table use that index automatically? + +Only if you analyse the table, and it's a "win". See the various +past discussion on -general, for instance, about index use, and the +FAQ. + +> Do I need to reindex that index after insertions? + +No, but you need to analyse. + +A + +-- +---- +Andrew Sullivan 204-4141 Yonge Street +Liberty RMS Toronto, Ontario Canada + M2P 2A8 + +1 416 646 3304 x110 + +