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Re: BUG #6565: GEQO documentation discrepancy after 9.0 change?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: gcottenc(at)gmail(dot)com
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #6565: GEQO documentation discrepancy after 9.0 change?
Date: 2012-04-09 14:30:23
Message-ID: CA+TgmoYx2v7gtZLe+qcqNDhJVeDSBnOsF5tzfrvCP-2tyB9=gQ@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-bugs
On Thu, Mar 29, 2012 at 3:36 AM,  <gcottenc(at)gmail(dot)com> wrote:
> The following bug has been logged on the website:
>
> Bug reference:      6565
> Logged by:          Guillaume Cottenceau
> Email address:      gcottenc(at)gmail(dot)com
> PostgreSQL version: 9.1.3
> Operating system:   not relevant
> Description:
>
> 9.0 release notes contain:
>
> """
> E.8.3.1.4. GEQO
>
> Use the same random seed every time GEQO plans a query (Andres Freund)
>
> While the Genetic Query Optimizer (GEQO) still selects random plans, it now
> always selects the same random plans for identical queries, thus giving more
> consistent performance. You can modify geqo_seed to experiment with
> alternative plans.
> """
>
> However, documentation up to 9.1 (pg website) say:
>
> http://www.postgresql.org/docs/9.1/static/runtime-config-query.html#RUNTIME-CONFIG-QUERY-GEQO
>
> """GEQO's searching is randomized and therefore its plans may vary
> nondeterministically."""
>
> I guess this sentence is outdated now?

Hmm, sounds like it.  Does anyone think otherwise?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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