From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Jean-Philippe Côté <jean-philippe(dot)cote(at)crt(dot)umontreal(dot)ca>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Extremely irregular query performance |
Date: | 2006-01-20 16:42:11 |
Message-ID: | 200601201642.k0KGgBS23410@candle.pha.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Done, and paragraph added to 8.1.X. (7.3 mention retained for 8.1.X.)
---------------------------------------------------------------------------
Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
From | Date | Subject | |
---|---|---|---|
Next Message | Stephan Vollmer | 2006-01-20 16:49:53 | Re: Creation of tsearch2 index is very slow |
Previous Message | Tom Lane | 2006-01-20 16:34:49 | Re: Extremely irregular query performance |