Re: Hash Join cost estimates

Jeff Davis <pgsql@j-davis.com> writes:
> Yes, I have run into this issue (or something very similar). I don't
> understand why the bucketsize even matters much -- assuming few hash
> collisions, we are not actually evaluating the quals any more times than
> necessary. So why all of the hashjoin-specific logic in determining the
> number of qual evaluations? The only reason I can think of is to model
> the cost of comparing the hashes themselves.

I think the point is that there may *not* be few hash collisions ...
        regards, tom lane