From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <pgman@candle.pha.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 11:34:49 -0500
Message-ID: <18684.1137774889@sss.pgh.pa.us> (raw)
In-Reply-To: <200601201619.k0KGJWE19919@candle.pha.pa.us>
References: <200601201619.k0KGJWE19919@candle.pha.pa.us>
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, pgman@candle.pha.pa.us, simon@2ndquadrant.com, jean-philippe.cote@crt.umontreal.ca
Subject: Re: Extremely irregular query performance
In-Reply-To: <18684.1137774889@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox