From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Jean-Philippe Cote <jean-philippe.cote@crt.umontreal.ca>
Cc: 'Kenneth Marshall' <ktm@is.rice.edu>
Cc: 'Simon Riggs' <simon@2ndquadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Extremely irregular query performance
Date: Fri, 13 Jan 2006 23:23:33 -0500 (EST)
Message-ID: <200601140423.k0E4NX019385@candle.pha.pa.us> (raw)
In-Reply-To: <20060112201353.5C39138409A@crt0.crt.umontreal.ca>
Jean-Philippe Cote wrote:
>
>
> Can I actully know whether a given plan is excuted with GEQO on ?
> In other words, if I launch 'explain <query>', I'll get a given plan, but if I re-launch
> the <query> (withtout the 'explain' keyword), could I get a different
> plan given that GEQO induces some randomness ?
>
> >Is it the plan that is different in the fastest case with GEQO or is it
> >the time needed to plan that is causing the GEQO to beat the exhaustive
> >search?
Yes, is it likely that when using GEQO you would get a different plan
each time, so running it with and without EXPLAIN would produce
different plans.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
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To: pgsql-performance@postgresql.org
Cc: pgman@candle.pha.pa.us, jean-philippe.cote@crt.umontreal.ca, ktm@is.rice.edu, simon@2ndquadrant.com
Subject: Re: Extremely irregular query performance
In-Reply-To: <200601140423.k0E4NX019385@candle.pha.pa.us>
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