On 6/10/11 5:15 AM, Willy-Bas Loos wrote: > Hi, > > is there a way to change the sample size for statistics (that analyze > gathers)? > It is said to be 10%. i would like to raise that, because we are getting bas > estimations for n_distinct.
It's not 10%. We use a fixed sample size, which is configurable on the system, table, or column basis. Some reading (read all these pages to understand what you're doing): http://www.postgresql.org/docs/9.0/static/planner-stats.html http://www.postgresql.org/docs/9.0/static/runtime-config-query.html#RUNTIME-CONFIG-QUERY-OTHER http://www.postgresql.org/docs/9.0/static/planner-stats-details.html http://www.postgresql.org/docs/9.0/static/sql-altertable.html (scroll down to "set storage" on that last page) -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
