Per a recent bug in which the planner can behave very differently at <
100, and accounting for the fact that analyze is still plenty fast on
today's systems even at a tenfold increase, attached is a patch to
change default_statistics_target from 10 to 100.
Index: doc/src/sgml/config.sgml
===================================================================
RCS file: /projects/cvsroot/pgsql/doc/src/sgml/config.sgml,v
retrieving revision 1.152
diff -c -r1.152 config.sgml
*** doc/src/sgml/config.sgml 1 Nov 2007 17:06:30 -0000 1.152
--- doc/src/sgml/config.sgml 14 Nov 2007 04:32:15 -0000
***************
*** 2150,2156 ****
not had a column-specific target set via <command>ALTER TABLE
SET STATISTICS</>. Larger values increase the time needed to
do <command>ANALYZE</>, but might improve the quality of the
! planner's estimates. The default is 10. For more information
on the use of statistics by the <productname>PostgreSQL</>
query planner, refer to <xref linkend="planner-stats">.
</para>
--- 2150,2156 ----
not had a column-specific target set via <command>ALTER TABLE
SET STATISTICS</>. Larger values increase the time needed to
do <command>ANALYZE</>, but might improve the quality of the
! planner's estimates. The default is 100. For more information
on the use of statistics by the <productname>PostgreSQL</>
query planner, refer to <xref linkend="planner-stats">.
</para>
Index: src/backend/commands/analyze.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/commands/analyze.c,v
retrieving revision 1.110
diff -c -r1.110 analyze.c
*** src/backend/commands/analyze.c 24 Oct 2007 20:55:36 -0000 1.110
--- src/backend/commands/analyze.c 14 Nov 2007 04:32:16 -0000
***************
*** 62,68 ****
/* Default statistics target (GUC parameter) */
! int default_statistics_target = 10;
/* A few variables that don't seem worth passing around as parameters */
static int elevel = -1;
--- 62,68 ----
/* Default statistics target (GUC parameter) */
! int default_statistics_target = 100;
/* A few variables that don't seem worth passing around as parameters */
static int elevel = -1;
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/guc.c,v
retrieving revision 1.425
diff -c -r1.425 guc.c
*** src/backend/utils/misc/guc.c 11 Nov 2007 19:22:49 -0000 1.425
--- src/backend/utils/misc/guc.c 14 Nov 2007 04:32:17 -0000
***************
*** 1117,1123 ****
"column-specific target set via ALTER TABLE SET STATISTICS.")
},
&default_statistics_target,
! 10, 1, 1000, NULL, NULL
},
{
{"from_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
--- 1117,1123 ----
"column-specific target set via ALTER TABLE SET STATISTICS.")
},
&default_statistics_target,
! 100, 1, 1000, NULL, NULL
},
{
{"from_collapse_limit", PGC_USERSET, QUERY_TUNING_OTHER,
Index: src/backend/utils/misc/postgresql.conf.sample
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/postgresql.conf.sample,v
retrieving revision 1.232
diff -c -r1.232 postgresql.conf.sample
*** src/backend/utils/misc/postgresql.conf.sample 9 Nov 2007 17:31:07 -0000 1.232
--- src/backend/utils/misc/postgresql.conf.sample 14 Nov 2007 04:32:17 -0000
***************
*** 218,224 ****
# - Other Planner Options -
! #default_statistics_target = 10 # range 1-1000
#constraint_exclusion = off
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
--- 218,224 ----
# - Other Planner Options -
! #default_statistics_target = 100 # range 1-1000
#constraint_exclusion = off
#from_collapse_limit = 8
#join_collapse_limit = 8 # 1 disables collapsing of explicit
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