Re: Extremely irregular query performance

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От Tom Lane
Тема Re: Extremely irregular query performance
Дата
Msg-id 18684.1137774889@sss.pgh.pa.us
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Ответ на Re: Extremely irregular query performance  (Bruce Momjian <pgman@candle.pha.pa.us>)
Ответы Re: Extremely irregular query performance  (Bruce Momjian <pgman@candle.pha.pa.us>)
Список pgsql-performance
Bruce Momjian <pgman@candle.pha.pa.us> writes:
>     <para>
> !    Genetic query optimization (<acronym>GEQO</acronym>) randomly
> !    tests execution plans.  Therefore, when the number of tables
> !    exceeds <varname>geqo</> and genetic query optimization is in use,
> !    the execution plan will change each time the statement is executed.
>     </para>

geqo_threshold, please --- geqo is a boolean.

Possibly better wording:  Therefore, when the number of tables exceeds
geqo_threshold causing genetic query optimization to be used, the
execution plan is likely to change each time the statement is executed.

            regards, tom lane

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