Re: Shared Buffer setting in postgresql.conf

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Josh Trutwin" <josh(at)trutwins(dot)homeip(dot)net>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Shared Buffer setting in postgresql.conf
Date: 2007-10-10 20:58:54
Message-ID: dcc563d10710101358p55abb925pba894a693b21718f@mail.gmail.com
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On 10/10/07, Josh Trutwin <josh(at)trutwins(dot)homeip(dot)net> wrote:
> On Wed, 10 Oct 2007 10:20:02 -0500
> "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com> wrote:
>
> > In 7.4, using 25% is often too high a setting for it to handle well,
> > and the practical useful maximum is usually under 10,000
> > shared_buffers, and often closer to 1,000 to 5,000
>
> Scott - interesting reply. Is this also true for 8.1? I currently
> have mine set to 16384 - server has 3.5 GB of total memory.

No, starting with 8.0, the code to manage the shared_buffers is much
more efficient with large numbers of shared buffers. With 8.0 and up
the primary considerations are that the shared_buffers be big enough
to hold your working set, but not so big as to run the system out of
memory for other things, sorts, kernel caching, etc...

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