2001-09-07 04:41:30 +08:00
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From pgsql-hackers-owner+M11649@postgresql.org Wed Aug 1 15:22:46 2001
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Return-path: <pgsql-hackers-owner+M11649@postgresql.org>
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Received: from postgresql.org (webmail.postgresql.org [216.126.85.28])
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by candle.pha.pa.us (8.10.1/8.10.1) with ESMTP id f71JMjN09768
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for <pgman@candle.pha.pa.us>; Wed, 1 Aug 2001 15:22:45 -0400 (EDT)
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Received: from postgresql.org.org (webmail.postgresql.org [216.126.85.28])
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by postgresql.org (8.11.3/8.11.1) with SMTP id f71JMUf62338;
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Wed, 1 Aug 2001 15:22:30 -0400 (EDT)
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(envelope-from pgsql-hackers-owner+M11649@postgresql.org)
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Received: from sectorbase2.sectorbase.com (sectorbase2.sectorbase.com [63.88.121.62] (may be forged))
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by postgresql.org (8.11.3/8.11.1) with SMTP id f71J4df57086
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for <pgsql-hackers@postgresql.org>; Wed, 1 Aug 2001 15:04:40 -0400 (EDT)
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(envelope-from vmikheev@SECTORBASE.COM)
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Received: by sectorbase2.sectorbase.com with Internet Mail Service (5.5.2653.19)
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id <PG1LSSPZ>; Wed, 1 Aug 2001 12:04:31 -0700
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Message-ID: <3705826352029646A3E91C53F7189E32016705@sectorbase2.sectorbase.com>
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From: "Mikheev, Vadim" <vmikheev@SECTORBASE.COM>
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To: "'pgsql-hackers@postgresql.org'" <pgsql-hackers@postgresql.org>
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Subject: [HACKERS] Using POSIX mutex-es
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Date: Wed, 1 Aug 2001 12:04:24 -0700
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MIME-Version: 1.0
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Sender: pgsql-hackers-owner@postgresql.org
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2002-01-24 02:40:22 +08:00
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Status: RO
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2001-09-07 04:41:30 +08:00
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1. Just changed
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TAS(lock) to pthread_mutex_trylock(lock)
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S_LOCK(lock) to pthread_mutex_lock(lock)
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S_UNLOCK(lock) to pthread_mutex_unlock(lock)
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(and S_INIT_LOCK to share mutex-es between processes).
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2. pgbench was initialized with scale 10.
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SUN WS 10 (512Mb), Solaris 2.6 (I'm unable to test on E4500 -:()
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-B 16384, wal_files 8, wal_buffers 256,
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checkpoint_segments 64, checkpoint_timeout 3600
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50 clients x 100 transactions
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(after initialization DB dir was saved and before each test
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copyed back and vacuum-ed).
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3. No difference.
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Mutex version maybe 0.5-1 % faster (eg: 37.264238 tps vs 37.083339 tps).
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So - no gain, but no performance loss "from using pthread library"
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(I've also run tests with 1 client), at least on Solaris.
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And so - looks like we can use POSIX mutex-es and conditional variables
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(not semaphores; man pthread_cond_wait) and should implement light lmgr,
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probably with priority locking.
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Vadim
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---------------------------(end of broadcast)---------------------------
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TIP 2: you can get off all lists at once with the unregister command
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(send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
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2002-01-24 02:40:22 +08:00
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From pgsql-hackers-owner+M18052=candle.pha.pa.us=pgman@postgresql.org Wed Jan 23 13:39:19 2002
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Return-path: <pgsql-hackers-owner+M18052=candle.pha.pa.us=pgman@postgresql.org>
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Received: from server1.pgsql.org (www.postgresql.org [64.49.215.9])
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for <pgman@candle.pha.pa.us>; Wed, 23 Jan 2002 13:39:18 -0500 (EST)
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for <pgsql-hackers@postgreSQL.org>; Wed, 23 Jan 2002 13:19:08 -0500 (EST)
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2001-09-07 04:41:30 +08:00
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(envelope-from pgman@candle.pha.pa.us)
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2002-01-24 02:40:22 +08:00
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by candle.pha.pa.us (8.11.6/8.10.1) id g0NIJ5i24508
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for pgsql-hackers@postgreSQL.org; Wed, 23 Jan 2002 13:19:05 -0500 (EST)
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2001-09-07 04:41:30 +08:00
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From: Bruce Momjian <pgman@candle.pha.pa.us>
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2002-01-24 02:40:22 +08:00
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Message-ID: <200201231819.g0NIJ5i24508@candle.pha.pa.us>
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Subject: [HACKERS] Savepoints
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To: PostgreSQL-development <pgsql-hackers@postgresql.org>
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Date: Wed, 23 Jan 2002 13:19:05 -0500 (EST)
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X-Mailer: ELM [version 2.4ME+ PL96 (25)]
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2001-09-07 04:41:30 +08:00
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Sender: pgsql-hackers-owner@postgresql.org
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2002-01-24 02:40:22 +08:00
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Status: RO
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I have talked in the past about a possible implementation of
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savepoints/nested transactions. I would like to more formally outline
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my ideas below.
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We have talked about using WAL for such a purpose, but that requires WAL
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files to remain for the life of a transaction, which seems unacceptable.
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Other database systems do that, and it is a pain for administrators. I
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realized we could do some sort of WAL compaction, but that seems quite
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complex too.
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Basically, under my plan, WAL would be unchanged. WAL's function is
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crash recovery, and it would retain that. There would also be no
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on-disk changes. I would use the command counter in certain cases to
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identify savepoints.
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My idea is to keep savepoint undo information in a private area per
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backend, either in memory or on disk. We can either save the
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relid/tids of modified rows, or if there are too many, discard the
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saved ones and just remember the modified relids. On rollback to save
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point, either clear up the modified relid/tids, or sequential scan
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through the relid and clear up all the tuples that have our transaction
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id and have command counters that are part of the undo savepoint.
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It seems marking undo savepoint rows with a fixed aborted transaction id
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would be the easiest solution.
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Of course, we only remember modified rows when we are in savepoints, and
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only undo them when we rollback to a savepoint. Transaction processing
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remains the same.
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There is no reason for other backend to be able to see savepoint undo
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information, and keeping it private greatly simplifies the
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implementation.
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2001-09-07 04:41:30 +08:00
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--
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Bruce Momjian | http://candle.pha.pa.us
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pgman@candle.pha.pa.us | (610) 853-3000
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+ If your life is a hard drive, | 830 Blythe Avenue
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+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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---------------------------(end of broadcast)---------------------------
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2002-01-24 02:40:22 +08:00
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TIP 6: Have you searched our list archives?
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2001-09-07 04:41:30 +08:00
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2002-01-24 02:40:22 +08:00
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http://archives.postgresql.org
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2001-09-07 04:41:30 +08:00
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2002-01-24 03:22:08 +08:00
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From hstenger@adinet.com.uy Wed Jan 23 14:13:33 2002
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Return-path: <hstenger@adinet.com.uy>
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Received: from correo.adinet.com.uy (fecorreo01.adinet.com.uy [206.99.44.217])
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by candle.pha.pa.us (8.11.6/8.10.1) with ESMTP id g0NJDWU29832
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for <pgman@candle.pha.pa.us>; Wed, 23 Jan 2002 14:13:33 -0500 (EST)
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Received: from adinet.com.uy (200.61.76.155) by correo.adinet.com.uy (5.5.052) (authenticated as hstenger@adinet.com.uy)
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id 3C4DBC5C00017E9F; Wed, 23 Jan 2002 16:13:25 -0300
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Message-ID: <3C4F0BC0.5CFBB919@adinet.com.uy>
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Date: Wed, 23 Jan 2002 16:15:12 -0300
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From: Haroldo Stenger <hstenger@adinet.com.uy>
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X-Mailer: Mozilla 4.78 [en] (Win98; U)
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X-Accept-Language: en
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To: Bruce Momjian <pgman@candle.pha.pa.us>
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cc: PostgreSQL-development <pgsql-hackers@postgreSQL.org>
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Subject: Re: [HACKERS] Savepoints
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References: <200201231819.g0NIJ5i24508@candle.pha.pa.us>
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Content-Type: text/plain; charset=us-ascii
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Status: OR
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Bruce Momjian wrote:
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>
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> Basically, under my plan, WAL would be unchanged. WAL's function is
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> crash recovery, and it would retain that. There would also be no
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> on-disk changes. I would use the command counter in certain cases to
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> identify savepoints.
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This is a pointer to the previous August thread, where your original proposal
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was posted, and some WAL/not WAL discussion took place. Just not to repeat the
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already mentioned points. Oh, it's google archive just for fun, and to not
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overload hub.org ;-)
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http://groups.google.com/groups?hl=en&threadm=200108050432.f754Wdo11696%40candle.pha.pa.us&rnum=1&prev=/groups%3Fhl%3Den%26selm%3D200108050432.f754Wdo11696%2540candle.pha.pa.us
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Regards,
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Haroldo.
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