From: | Greg Smith <gsmith(at)gregsmith(dot)com> |
---|---|
To: | Josh Berkus <josh(at)agliodbs(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: 2GB or not 2GB |
Date: | 2008-05-29 01:06:06 |
Message-ID: | Pine.GSO.4.64.0805282042190.1115@westnet.com |
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Lists: | pgsql-performance |
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(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD
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