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. -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
