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Set a default autovacuum vacuum_cost_delay value of 20ms, to avoid excessive

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I/O utilization, per discussion.

While at it, lower the autovacuum vacuum and analyze threshold values to 50
tuples.  It is a bit higher (i.e. more conservative) than what I originally
proposed but much better than the old values for small tables.
This commit is contained in:
Alvaro Herrera 2007-07-24 01:53:56 +00:00
parent ab7d2b6a73
commit 53d2951be7
3 changed files with 12 additions and 11 deletions
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9
doc/src/sgml/config.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.131 2007/07/18 12:00:47 mha Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.132 2007/07/24 01:53:55 alvherre Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@ -3247,7 +3247,7 @@ SELECT * FROM parent WHERE key = 2400;
<para>
Specifies the minimum number of updated or deleted tuples needed
to trigger a <command>VACUUM</> in any one table.
The default is 500 tuples.
The default is 50 tuples.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
@ -3265,7 +3265,7 @@ SELECT * FROM parent WHERE key = 2400;
<para>
Specifies the minimum number of inserted, updated or deleted tuples
needed to trigger an <command>ANALYZE</> in any one table.
The default is 250 tuples.
The default is 50 tuples.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in
@ -3343,8 +3343,9 @@ SELECT * FROM parent WHERE key = 2400;
<para>
Specifies the cost delay value that will be used in automatic
<command>VACUUM</> operations. If <literal>-1</> is
specified (which is the default), the regular
specified, the regular
<xref linkend="guc-vacuum-cost-delay"> value will be used.
The default value is 20 milliseconds.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
This setting can be overridden for individual tables by entries in

8
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 1.405 2007/07/10 13:14:21 mha Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.406 2007/07/24 01:53:56 alvherre Exp $
*
*--------------------------------------------------------------------
*/
@ -1348,7 +1348,7 @@ static struct config_int ConfigureNamesInt[] =
GUC_UNIT_MS
},
&autovacuum_vac_cost_delay,
-1, -1, 1000, NULL, NULL
20, -1, 1000, NULL, NULL
},
{
@ -1656,7 +1656,7 @@ static struct config_int ConfigureNamesInt[] =
NULL
},
&autovacuum_vac_thresh,
500, 0, INT_MAX, NULL, NULL
50, 0, INT_MAX, NULL, NULL
},
{
{"autovacuum_analyze_threshold", PGC_SIGHUP, AUTOVACUUM,
@ -1664,7 +1664,7 @@ static struct config_int ConfigureNamesInt[] =
NULL
},
&autovacuum_anl_thresh,
250, 0, INT_MAX, NULL, NULL
50, 0, INT_MAX, NULL, NULL
},
{
/* see varsup.c for why this is PGC_POSTMASTER not PGC_SIGHUP */

6
src/backend/utils/misc/postgresql.conf.sample
View File

@ -381,9 +381,9 @@
#log_autovacuum = -1 # -1 is disabled, 0 logs all actions
# and their durations, > 0 logs only
# actions running at least N msec.
#autovacuum_vacuum_threshold = 500 # min # of tuple updates before
#autovacuum_vacuum_threshold = 50 # min # of tuple updates before
# vacuum
#autovacuum_analyze_threshold = 250 # min # of tuple updates before
#autovacuum_analyze_threshold = 50 # min # of tuple updates before
# analyze
#autovacuum_vacuum_scale_factor = 0.2 # fraction of rel size before
# vacuum
@ -391,7 +391,7 @@
# analyze
#autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum
# (change requires restart)
#autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for
#autovacuum_vacuum_cost_delay = 20 # default vacuum cost delay for
# autovacuum, -1 means use
# vacuum_cost_delay
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for