From: Greg Smith <gsmith@gregsmith.com>
To: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: 2GB or not 2GB
Date: Wed, 28 May 2008 21:06:06 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0805282042190.1115@westnet.com> (raw)
In-Reply-To: <200805281659.26945.josh@agliodbs.com>
References: <200805281659.26945.josh@agliodbs.com>
On Wed, 28 May 2008, Josh Berkus wrote:
> shared_buffers: according to witnesses, Greg Smith presented at East that
> based on PostgreSQL's buffer algorithms, buffers above 2GB would not
> really receive significant use. However, Jignesh Shah has tested that on
> workloads with large numbers of connections, allocating up to 10GB
> improves performance.
Lies! The only upper-limit for non-Windows platforms I mentioned was
suggesting those recent tests at Sun showed a practical limit in the low
multi-GB range.
I've run with 4GB usefully for one of the multi-TB systems I manage, the
main index on the most frequently used table is 420GB and anything I can
do to keep the most popular parts of that pegged in memory seems to help.
I haven't tried to isolate the exact improvement going from 2GB to 4GB
with benchmarks though.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com, josh@agliodbs.com
Subject: Re: 2GB or not 2GB
In-Reply-To: <Pine.GSO.4.64.0805282042190.1115@westnet.com>
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