David Kerr wrote:
the db, xlog and logs are all on separate areas of the SAN. separate I/O controllers, etc on the SAN. it's setup well, I wouldn't expect contention there.
Just because you don't expect it doesn't mean it's not there. Particularly something as complicated as a SAN setup, presuming anything without actually benchmarking it is a recipe for fuzzy diagnostics when problems pop up. If you took anyone's word that your SAN has good performance without confirming it yourself, that's a path that's lead many to trouble.
Anyway, as Robert already stated, effective_cache_size only impacts how some very specific types of queries are executed; that's it. If there's some sort of query behavior involved in your load, maybe that has something to do with your slowdown, but it doesn't explain general slow performance. Other possibilities include that something else changed when you reloaded the server as part of that, or it's a complete coincidence--perhaps autoanalyze happened to finish at around the same time and it lead to new plans.
-- Greg Smith 2ndQuadrant US Baltimore, MD PostgreSQL Training, Services and Support greg@xxxxxxxxxxxxxxx www.2ndQuadrant.us -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
