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| author | Peter Eisentraut <peter_e@gmx.net> | 2018-07-16 13:35:41 +0200 |
|---|---|---|
| committer | Peter Eisentraut <peter_e@gmx.net> | 2018-07-16 13:35:41 +0200 |
| commit | f7cb2842bf47715133b40e4a503f35dbe60d1b72 (patch) | |
| tree | 645468d969635b10cb87e1134b60afcd26456339 /doc/src | |
| parent | a06e56b247feb2812bad5cf60fd9c0128d81f5c0 (diff) | |
Add plan_cache_mode setting
This allows overriding the choice of custom or generic plan.
Author: Pavel Stehule <pavel.stehule@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAFj8pRAGLaiEm8ur5DWEBo7qHRWTk9HxkuUAz00CZZtJj-LkCA%40mail.gmail.com
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index e307bb4e8e9..4d48d93305a 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -4616,6 +4616,36 @@ SELECT * FROM parent WHERE key = 2400; </listitem> </varlistentry> + <varlistentry id="guc-plan-cache_mode" xreflabel="plan_cache_mode"> + <term><varname>plan_cache_mode</varname> (<type>enum</type>) + <indexterm> + <primary><varname>plan_cache_mode</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Prepared statements (either explicitly prepared or implicitly + generated, for example in PL/pgSQL) can be executed using custom or + generic plans. A custom plan is replanned for a new parameter value, + a generic plan is reused for repeated executions of the prepared + statement. The choice between them is normally made automatically. + This setting overrides the default behavior and forces either a custom + or a generic plan. This can be used to work around performance + problems in specific cases. Note, however, that the plan cache + behavior is subject to change, so this setting, like all settings that + force the planner's hand, should be reevaluated regularly. + </para> + + <para> + The allowed values are <literal>auto</literal>, + <literal>force_custom_plan</literal> and + <literal>force_generic_plan</literal>. The default value is + <literal>auto</literal>. The setting is applied when a cached plan is + to be executed, not when it is prepared. + </para> + </listitem> + </varlistentry> + </variablelist> </sect2> </sect1> |