Hmm, perhaps we could usefully aggregate auto_explain output. On Thu, Feb 9, 2012 at 7:32 AM, Jeff Janes <jeff.janes@xxxxxxxxx> wrote: > On Wed, Feb 8, 2012 at 6:28 PM, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: >> On Wed, Feb 8, 2012 at 6:45 PM, Peter van Hardenberg <pvh@xxxxxx> wrote: >>> Having read the thread, I don't really see how I could study what a >>> more principled value would be. >> >> Agreed. Just pointing out more research needs to be done. >> >>> That said, I have access to a very large fleet in which to can collect >>> data so I'm all ears for suggestions about how to measure and would >>> gladly share the results with the list. >> >> I wonder if some kind of script that grabbed random queries and ran >> them with explain analyze and various random_page_cost to see when >> they switched and which plans are faster would work? > > But if you grab a random query and execute it repeatedly, you > drastically change the caching. > > Results from any execution after the first one are unlikely to give > you results which are meaningful to the actual production situation. > > Cheers, > > Jeff -- Peter van Hardenberg San Francisco, California "Everything was beautiful, and nothing hurt." -- Kurt Vonnegut -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
