Jesper Krogh <jesper@krogh.cc> writes:
> When something evaluates to "null" isn't included in the result,
> shouldn't the query-planner
> then take the null_frac into account when computing the estimate?
The proposed patch seems wrong to me: if we're estimating on the basis
of most-common-value fractions, the null_frac is already accounted for,
because it's not part of the MCV selectivity fractions. IOW, aren't you
double-counting the null fraction?
regards, tom lane
