Tambet, > I was following the cpu_tuple_cost thread and wondering, if it could be > possible to make PQA style utility to calculate configuration-specific > values for planner cost constants. It could make use of output of > log_(statement|parser|planner|executor)_stats, tough I'm not sure if the > output contains anything useful for those purposes.
Yeah, that's something I need to look at. > Otherwise it could just collect statements, run EXPLAIN ANALYZE for all > of them and then play with planner cost constants to get the estimated > values as close as possible to actual values. Something like Goal Seek > in Excel, if you pardon my reference to MS :). That's not really practical. There are currently 5 major query tuning parameters, not counting the memory adjustments which really can't be left out. You can't realistically test all combinations of 6 variables. > Somewhat similar project seems to be pgautotune from pgFoundry, but it > only considers shared_buffers, sort_mem and vacuum_mem. And it seems to > use synthetic data instead of actual database and actual statements from > log. And it has been inactive for a while. Yeah, pg_autotune is a dead project. Once we got OSDL able to run tests, we came up with some rules-of-thumb which are more useful than autotune's output. More importantly, the approach doesn't scale to the 15-20 GUCs which we'd realistically want to test. -- Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly