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Increase the default value of default_statistics_target from 10 to 100,
and its maximum value from 1000 to 10000. ALTER TABLE SET STATISTICS similarly now allows a value up to 10000. Per discussion.
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@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.199 2008/12/08 15:11:39 mha Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.200 2008/12/13 19:13:43 tgl Exp $ -->
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<chapter Id="runtime-config">
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<title>Server Configuration</title>
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@ -2133,7 +2133,7 @@ archive_command = 'copy "%p" "C:\\server\\archivedir\\%f"' # Windows
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not had a column-specific target set via <command>ALTER TABLE
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SET STATISTICS</>. Larger values increase the time needed to
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do <command>ANALYZE</>, but might improve the quality of the
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planner's estimates. The default is 10. For more information
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planner's estimates. The default is 100. For more information
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on the use of statistics by the <productname>PostgreSQL</>
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query planner, refer to <xref linkend="planner-stats">.
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</para>
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@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/perform.sgml,v 1.68 2007/12/28 21:03:31 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/perform.sgml,v 1.69 2008/12/13 19:13:43 tgl Exp $ -->
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<chapter id="performance-tips">
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<title>Performance Tips</title>
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@ -562,7 +562,7 @@ SELECT attname, n_distinct, most_common_vals FROM pg_stats WHERE tablename = 'ro
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column-by-column basis using the <command>ALTER TABLE SET STATISTICS</>
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command, or globally by setting the
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<xref linkend="guc-default-statistics-target"> configuration variable.
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The default limit is presently 10 entries. Raising the limit
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The default limit is presently 100 entries. Raising the limit
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might allow more accurate planner estimates to be made, particularly for
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columns with irregular data distributions, at the price of consuming
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more space in <structname>pg_statistic</structname> and slightly more
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@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.101 2008/11/14 10:22:45 petere Exp $
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$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.102 2008/12/13 19:13:44 tgl Exp $
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PostgreSQL documentation
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-->
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@ -142,7 +142,7 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
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This form
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sets the per-column statistics-gathering target for subsequent
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<xref linkend="sql-analyze" endterm="sql-analyze-title"> operations.
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The target can be set in the range 0 to 1000; alternatively, set it
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The target can be set in the range 0 to 10000; alternatively, set it
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to -1 to revert to using the system default statistics
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target (<xref linkend="guc-default-statistics-target">).
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For more information on the use of statistics by the
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@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/ref/analyze.sgml,v 1.24 2008/11/14 10:22:45 petere Exp $
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$PostgreSQL: pgsql/doc/src/sgml/ref/analyze.sgml,v 1.25 2008/12/13 19:13:44 tgl Exp $
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PostgreSQL documentation
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-->
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@ -132,10 +132,10 @@ ANALYZE [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> [ ( <re
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will change slightly each time <command>ANALYZE</command> is run,
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even if the actual table contents did not change. This might result
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in small changes in the planner's estimated costs shown by
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<xref linkend="sql-explain" endterm="sql-explain-title">. In rare situations, this
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non-determinism will cause the query optimizer to choose a
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different query plan between runs of <command>ANALYZE</command>. To
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avoid this, raise the amount of statistics collected by
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<xref linkend="sql-explain" endterm="sql-explain-title">.
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In rare situations, this non-determinism will cause the planner's
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choices of query plans to change after <command>ANALYZE</command> is run.
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To avoid this, raise the amount of statistics collected by
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<command>ANALYZE</command>, as described below.
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</para>
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@ -148,7 +148,7 @@ ANALYZE [ VERBOSE ] [ <replaceable class="PARAMETER">table</replaceable> [ ( <re
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endterm="sql-altertable-title">). The target value sets the
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maximum number of entries in the most-common-value list and the
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maximum number of bins in the histogram. The default target value
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is 10, but this can be adjusted up or down to trade off accuracy of
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is 100, but this can be adjusted up or down to trade off accuracy of
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planner estimates against the time taken for
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<command>ANALYZE</command> and the amount of space occupied in
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<literal>pg_statistic</literal>. In particular, setting the
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