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@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD
