Re: [GENERAL] how to get accurate values in pg_statistic (continued)

Tom Lane wrote:
> Mary Edie Meredith <maryedie(at)osdl(dot)org> writes:
> > Stephan Szabo kindly responded to our earlier queries suggesting we look
> > at default_statistics_target and ALTER TABLE ALTER COLUMN SET
> > STATISTICS.
>
> > 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 | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073