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| author | Bruce Momjian <bruce@momjian.us> | 2010-02-23 02:47:27 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2010-02-23 02:47:27 +0000 |
| commit | 1379fb052fd18e87a5102e793bdb5b8bc2bf5d17 (patch) | |
| tree | b69657985dc83e6e2329bc55f98ae11716d6e6e7 /doc/src | |
| parent | 7cdadc62eac79ee9bd05b6a74d3ddfb96924a439 (diff) | |
| download | postgresql-1379fb052fd18e87a5102e793bdb5b8bc2bf5d17.tar.gz postgresql-1379fb052fd18e87a5102e793bdb5b8bc2bf5d17.zip | |
Document that expression indexes that call functions allow function-level
statistics.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/maintenance.sgml | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml index ecec84cc2d9..0b01467ee01 100644 --- a/doc/src/sgml/maintenance.sgml +++ b/doc/src/sgml/maintenance.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/maintenance.sgml,v 1.99 2010/02/08 04:33:51 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/maintenance.sgml,v 1.100 2010/02/23 02:47:27 momjian Exp $ --> <chapter id="maintenance"> <title>Routine Database Maintenance Tasks</title> @@ -318,6 +318,14 @@ SET STATISTICS</>, or change the database-wide default using the <xref linkend="guc-default-statistics-target"> configuration parameter. </para> + + <para> + Also, by default there is limited information available about + the selectivity of functions. However, if you create an expression + index that uses a function call, useful statistics will be + gathered about the function, which can greatly improve query + plans that use the expression index. + </para> </tip> </sect2> |