Re: 2GB or not 2GB

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