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Message-ID: <dcc563d10710101358p55abb925pba894a693b21718f@mail.gmail.com>
Date: Wed, 10 Oct 2007 15:58:54 -0500
From: "Scott Marlowe" <scott.marlowe@gmail.com>
To: "Josh Trutwin" <josh@trutwins.homeip.net>
Subject: Re: Shared Buffer setting in postgresql.conf
Cc: pgsql-performance@postgresql.org
In-Reply-To: <20071010153201.65331672@joplin.trutwins.homeip.net>
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References: <fe27bfd40710091312l1d0bf61fx6caecdd74b7dec50@mail.gmail.com>
	<dcc563d10710100820p520698cctb65e5f5dc1a3a6e5@mail.gmail.com>
	<20071010153201.65331672@joplin.trutwins.homeip.net>

On 10/10/07, Josh Trutwin <josh@trutwins.homeip.net> wrote:
> On Wed, 10 Oct 2007 10:20:02 -0500
> "Scott Marlowe" <scott.marlowe@gmail.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...