From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: Jean-Philippe Côté <jean-philippe.cote@crt.umontreal.ca>
Cc: pgsql-performance@postgresql.org
Subject: Re: Extremely irregular query performance
Date: Fri, 20 Jan 2006 11:42:11 -0500 (EST)
Message-ID: <200601201642.k0KGgBS23410@candle.pha.pa.us> (raw)
In-Reply-To: <18684.1137774889@sss.pgh.pa.us>
Done, and paragraph added to 8.1.X. (7.3 mention retained for 8.1.X.)
---------------------------------------------------------------------------
Tom Lane wrote:
> 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
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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To: pgsql-performance@postgresql.org
Cc: pgman@candle.pha.pa.us, tgl@sss.pgh.pa.us, simon@2ndquadrant.com, jean-philippe.cote@crt.umontreal.ca
Subject: Re: Extremely irregular query performance
In-Reply-To: <200601201642.k0KGgBS23410@candle.pha.pa.us>
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