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Reduce default value of max_prepared_transactions from 50 to 5. This

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saves nearly 700kB in the default shared memory segment size, which seems
worthwhile, and it is a feature that many users won't use anyway.  Per
Heikki's argument, there is no point in a compromise value --- those who
are using 2PC at all will probably want it at least equal to max_connections.
But we can't set it to zero by default without breaking the prepared_xacts
regression test.
This commit is contained in:
Tom Lane 2005-08-29 21:38:18 +00:00
parent 8aec77fb9f
commit 037709e0b3
4 changed files with 7 additions and 7 deletions
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4
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.348 2005/08/24 18:56:07 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.349 2005/08/29 21:38:17 tgl Exp $
-->
<chapter Id="runtime">
@ -1179,7 +1179,7 @@ SET ENABLE_SEQSCAN TO OFF;
endterm="sql-prepare-transaction-title">).
Setting this parameter to zero disables the prepared-transaction
feature.
The default is 50.
The default is 5.
This option can only be set at server start.
</para>

4
src/backend/access/transam/twophase.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/twophase.c,v 1.10 2005/08/20 23:26:10 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/twophase.c,v 1.11 2005/08/29 21:38:18 tgl Exp $
*
* NOTES
* Each global transaction is associated with a global transaction
@ -64,7 +64,7 @@
#define TWOPHASE_DIR "pg_twophase"
/* GUC variable, can't be changed after startup */
int max_prepared_xacts = 50;
int max_prepared_xacts = 5;
/*
* This struct describes one global transaction that is in prepared state

4
src/backend/utils/misc/guc.c
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@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.286 2005/08/22 17:34:59 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.287 2005/08/29 21:38:18 tgl Exp $
*
*--------------------------------------------------------------------
*/
@ -1203,7 +1203,7 @@ static struct config_int ConfigureNamesInt[] =
NULL
},
&max_prepared_xacts,
50, 0, INT_MAX, NULL, NULL
5, 0, INT_MAX, NULL, NULL
},
#ifdef LOCK_DEBUG

2
src/backend/utils/misc/postgresql.conf.sample
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@ -90,7 +90,7 @@
#shared_buffers = 1000 # min 16 or max_connections*2, 8KB each
#temp_buffers = 1000 # min 100, 8KB each
#max_prepared_transactions = 50 # can be 0 or more
#max_prepared_transactions = 5 # can be 0 or more
#work_mem = 1024 # min 64, size in KB
#maintenance_work_mem = 16384 # min 1024, size in KB
#max_stack_depth = 2048 # min 100, size in KB