Tom Lane wrote:
> Mary Edie Meredith <[EMAIL PROTECTED]> writes:
> > Stephan Szabo kindly responded to our earlier queries suggesting we look
> > at default_statistics_target and ALTER TABLE ALTER COLUMN SET
> > These determine the number of bins in the histogram for a given column. 
> > But for a large number of rows (for example 6 million) the maximum value
> > (1000) does not guarantee that ANALYZE will do a full scan of the table.
> > We do not see a way to guarantee the same statistics run to run without
> > forcing ANALYZE to examine every row of every table.  
> Do you actually still have a problem with the plans changing when the
> stats target is above 100 or so?  I think the notion of "force ANALYZE
> to do a full scan" is inherently wrongheaded ... it certainly would not
> produce numbers that have anything to do with ordinary practice.
> If you have data statistics that are so bizarre that the planner still
> gets things wrong with a target of 1000, then I'd like to know more
> about why.

Has there been any progress in determining if the number of default
buckets (10) is the best value?

  Bruce Momjian                        |
  [EMAIL PROTECTED]               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
      joining column's datatypes do not match

Reply via email to