Re: Proposal - improve eqsel estimates by including histogram bucket numdistinct statistics

Gregory Stark <stark@enterprisedb.com> writes:
> It's possible that the second option I described -- teaching Append when to
> use something other than sum() -- would only work in the cases where
> constraint exclusion could be fixed though. In which case having fractional
> row counts might actually be necessary. 

The above is just armwaving.  IMHO, if you don't understand the
structure of the table set then you're not going to be able to get the
desired behavior via fractional rowcounts either.
        regards, tom lane