Thread: optimization histograms

HI,

for the histograms for cost based optimization, is there a rule of thumb on how often to rebuild them? They are
obviouslynot being continuously updated...what is the state of the art in this area, do all the other databases also
endup with stale statistics every now and then and have to keep rebuilding the stats?
 

thanks
-Amit

     

amit sehas <cun23@yahoo.com> 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