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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2001-02-15 04:28:50 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2001-02-15 04:28:50 +0000 |
| commit | 21deb428970ea6225d3122207c3910a01f84c770 (patch) | |
| tree | 852550112c4e3f20139808442eef6ea019b4fcc4 | |
| parent | 52cacf46b45fe92b91b3cb1ceef9db164bb328a8 (diff) | |
| download | postgresql-21deb428970ea6225d3122207c3910a01f84c770.tar.gz postgresql-21deb428970ea6225d3122207c3910a01f84c770.zip | |
Clarify meaning of GEQO_THRESHOLD parameter.
| -rw-r--r-- | doc/src/sgml/runtime.sgml | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml index 4322a1f42e1..e26662117e1 100644 --- a/doc/src/sgml/runtime.sgml +++ b/doc/src/sgml/runtime.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.50 2001/02/10 00:50:18 petere Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.51 2001/02/15 04:28:50 tgl Exp $ --> <Chapter Id="runtime"> @@ -639,7 +639,7 @@ env PGOPTIONS='-c geqo=off' psql algorithm: The pool size is the number of individuals in one population. Valid values are between 128 and 1024. If it is set to 0 (the default) a pool size of 2^(QS+1), where QS - is the number of relations in the query, is taken. The effort + is the number of FROM items in the query, is taken. The effort is used to calculate a default for generations. Valid values are between 1 and 80, 40 being the default. Generations specifies the number of iterations in the algorithm. The @@ -659,9 +659,10 @@ env PGOPTIONS='-c geqo=off' psql <term>GEQO_THRESHOLD (<type>integer</type>)</term> <listitem> <para> - Only use genetic query optimization for queries with at least - this many relations involved. The default is 11. For less - relations it is probably more efficient to use the + Use genetic query optimization to plan queries with at least + this many FROM items involved. (Note that a JOIN construct + counts as only one FROM item.) The default is 11. For simpler + queries it is usually best to use the deterministic, exhaustive planner. </para> </listitem> |