Re: optimization histograms

amit sehas  wrote:
> for the histograms for cost based optimization, is there a rule of
> thumb on how often to rebuild them?
In recent major versions, autovacuum should normally keep you in
good shape.  The exception is when you make major changes to the
contents of a table (such as in a bulk data load) and then
immediately try to use the table before autovacuum has had time to
notice the activity and generate fresh statistics; for these cases
you probably want to do a manual run.
For more information, see:
http://www.postgresql.org/docs/current/interactive/routine-vacuuming.html#VACUUM-FOR-STATISTICS
-Kevin