From: Dimitri Fontaine <dfontaine@hi-media.com>
To: pgsql-performance@postgresql.org
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Flavio Henrique Araque Gurgel <flavio@4linux.com.br>
Subject: Re: work_mem in high transaction rate database
Date: Wed, 4 Mar 2009 10:16:07 +0100
Message-ID: <200903041016.09765.dfontaine@hi-media.com> (raw)
In-Reply-To: <dcc563d10903031737ne79c349r4740dbad68e04640@mail.gmail.com>
References: <29144661.96951236126415852.JavaMail.root@mail.4linux.com.br>
<30792576.96971236126536868.JavaMail.root@mail.4linux.com.br>
<dcc563d10903031737ne79c349r4740dbad68e04640@mail.gmail.com>
Hi,
On Wednesday 04 March 2009 02:37:42 Scott Marlowe wrote:
> If some oddball query really needs a lot of work_mem,
> and benchmarks show something larger work_mem helps, consider raising
> the work_mem setting for that one query to something under 1G (way
> under 1G) That makes it noticeably faster. Don't allocate more than a
> test shows you helps.
The probably easiest way to integrate this into an existing application is
this way, in my experience:
BEGIN;
SET LOCAL work_mem TO '650MB';
SELECT -- the query requiring such a large setting
COMMIT;
Right after the commit the global configured work_mem (or the previous
session's one, in fact) will be in effect, you won't have to reset it yourself.
Regards,
--
dim
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To: pgsql-performance@postgresql.org
Cc: dfontaine@hi-media.com, scott.marlowe@gmail.com, flavio@4linux.com.br
Subject: Re: work_mem in high transaction rate database
In-Reply-To: <200903041016.09765.dfontaine@hi-media.com>
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