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Re: does the query planner consider work_mem?

From: Ants Aasma <ants(at)cybertec(dot)at>
To: Murat Tasan <mmuurr(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: does the query planner consider work_mem?
Date: 2012-05-30 18:25:53
Message-ID: CA+CSw_uuyJAC7xejcoD6n1b8XF-TKw8KU6d95ssXKaBVQ1HL8A@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, May 30, 2012 at 8:57 PM, Murat Tasan <mmuurr(at)gmail(dot)com> wrote:
> any insights here?

Have you tried running the slow option multiple times? According to
the explain output all of the time was accounted to the bitmap heap
scan. For the second explain plan the same node was fast. It looks to
me as the first explain on 8.4 was slow because the data was still on
disk. Raising work mem doubled the speed of the sort from 800ms to
400ms.

Regards,
Ants Aasma
-- 
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de

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