On Jul 3, 2012, at 10:16 AM, Bruce Momjian wrote: > On Fri, Jun 22, 2012 at 11:04:36AM -0700, David Kerr wrote: >> On Fri, Jun 22, 2012 at 01:27:51PM -0400, Tom Lane wrote: >> - David Kerr <dmk@xxxxxxxxxxxxxx> writes: >> - > I'm trying to work through a root cause on a performance problem. I'd like to >> - > be able to "show" that a problem was fixed by analyzing the table. >> - >> - > what i've done is >> - > set default_statistics_target=1 >> - > analyze <Table> >> - >> - > That gets rid of most of the rows in pg_stats, but i'm still getting decent performance. >> - >> - I usually do something like >> - >> - DELETE FROM pg_statistic WHERE starelid = 'foo'::regclass; >> - >> - (you need to be superuser to be allowed to do this). >> - >> - You may need to keep an eye on whether auto-analyze is coming along and >> - undoing what you did, too. >> - >> - regards, tom lane >> - >> >> Awesome, thanks! > > One cool trick I have seen is to do the DELETE pg_statistic in a multi-statement > transaction and then run query query, and roll it back. This allows the > statistics to be preserved, and for only your query to see empty > pg_statistic values for the table. > Nice! thanks! Dave -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
