On Thu, Aug 7, 2008 at 5:38 PM, Gregory Stark <stark@xxxxxxxxxxxxxxxx> wrote: > Measuring n_distinct from a sample is inherently difficult and unreliable. > When 98% of your table falls into those categories it's leaving very few > chances for the sample to find many other distinct values. > > I haven't seen the whole thread, if you haven't tried already you could try > raising the statistics target for these columns -- that's usually necessary > anyways when you have a very skewed distribution like this. > I did some tweaking on default_statistics_target earlier in the thread with no luck. I just retried it with default_statistics_target set to 500 and did the VACUUM ANALYZE on the other table this time and started to see better results and more of the behavior I would expect. Is there a way to set the stats target for just one column? That seems like what we might need to do. > Yeah, Heikki's suggested having a kind of "branch" plan node that knows how > where the break-point is between two plans and can call the appropriate one. > We don't have anything like that yet. > Is this already on a todo list or is there a bug for it?
