On Fri, May 29, 2009 at 1:30 PM, Dave Dutcher <dave@tridecap.com> wrote:
> From: Anne Rosset > Subject: Re: [PERFORM] Unexpected query plan results
> > > > > Thank Dave. We are using postgresql-server-8.2.4-1PGDG and > have work-mem set to 20MB. > What value would you advise? > thanks, > > Anne
Work-mem is kind of tricky because the right setting depends on how much ram your machine has, is the machine dedicated to postgres, and how many simultaneous connections you have. If this is a test server, and not used in production, you could just play around with the setting and see if your query gets any faster.
Right, the trick to remember is that you could possibly end up in a scenario where you have max_connections * work_mem being used just for sorting / joins and the rest of your memory will be swapped, so be careful not to push too high. Also, work_mem is not going to be fully allocated at fork time, it'll only use up to that much as needed.