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Change default commit_delay to zero, update documentation.

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This commit is contained in:
Tom Lane 2001-02-18 04:50:43 +00:00
parent 33cc5d8a4d
commit 57e0847180
4 changed files with 24 additions and 16 deletions
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12
doc/src/sgml/wal.sgml
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@ -1,4 +1,4 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.1 2001/01/24 23:15:19 petere Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.2 2001/02/18 04:50:43 tgl Exp $ -->
<chapter id="wal">
<title>Write-Ahead Logging (<acronym>WAL</acronym>)</title>
@ -290,15 +290,15 @@
</para>
<para>
The <varname>COMMIT_DELAY</varname> parameter defines for how long
the backend will be forced to sleep after writing a commit record
to the log with <function>LogInsert</function> call but before
The <varname>COMMIT_DELAY</varname> parameter defines for how many
microseconds the backend will sleep after writing a commit
record to the log with <function>LogInsert</function> but before
performing a <function>LogFlush</function>. This delay allows other
backends to add their commit records to the log so as to have all
of them flushed with a single log sync. Unfortunately, this
mechanism is not fully implemented at release 7.1, so there is at
present no point in changing this parameter from its default value
of 5 microseconds.
present usually no benefit to be gained from increasing this parameter
above its default value of zero.
</para>
</sect1>
</chapter>

22
src/backend/access/transam/xact.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.96 2001/01/24 19:42:51 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.97 2001/02/18 04:50:43 tgl Exp $
*
* NOTES
* Transaction aborts can now occur two ways:
@ -221,7 +221,7 @@ int XactIsoLevel;
#include "access/xlogutils.h"
int CommitDelay = 5; /* 1/200000 sec */
int CommitDelay = 0; /* in microseconds */
static void (*_RollbackFunc)(void*) = NULL;
static void *_RollbackData = NULL;
@ -667,7 +667,6 @@ RecordTransactionCommit()
{
XLogRecData rdata;
xl_xact_commit xlrec;
struct timeval delay;
XLogRecPtr recptr;
BufmgrCommit();
@ -686,11 +685,20 @@ RecordTransactionCommit()
/*
* Sleep before commit! So we can flush more than one
* commit records per single fsync.
* commit records per single fsync. (The idea is some other
* backend may do the XLogFlush while we're sleeping. This
* needs work however, because on most Unixen, the minimum
* select() delay is 10msec or more, which is way too long.)
*/
delay.tv_sec = 0;
delay.tv_usec = CommitDelay;
(void) select(0, NULL, NULL, NULL, &delay);
if (CommitDelay > 0)
{
struct timeval delay;
delay.tv_sec = 0;
delay.tv_usec = CommitDelay;
(void) select(0, NULL, NULL, NULL, &delay);
}
XLogFlush(recptr);
MyLastRecPtr.xrecoff = 0;

4
src/backend/utils/misc/guc.c
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@ -4,7 +4,7 @@
* Support for grand unified configuration scheme, including SET
* command, configuration file, and command line options.
*
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.29 2001/02/07 23:36:22 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.30 2001/02/18 04:50:43 tgl Exp $
*
* Copyright 2000 by PostgreSQL Global Development Group
* Written by Peter Eisentraut <peter_e@gmx.net>.
@ -291,7 +291,7 @@ ConfigureNamesInt[] =
0, 0, 16},
{"commit_delay", PGC_USERSET, &CommitDelay,
5, 0, 1000},
0, 0, 100000},
{NULL, 0, NULL, 0, 0, 0}
};

2
src/backend/utils/misc/postgresql.conf.sample
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@ -108,7 +108,7 @@
#wal_buffers = 8 # min 4
#wal_files = 0 # range 0-64
#wal_debug = 0 # range 0-16
#commit_delay = 5 # range 0-1000
#commit_delay = 0 # range 0-100000
#checkpoint_timeout = 300 # range 30-1800