Re: [HACKERS] Regression in join selectivity estimations when usingforeign keys

On 20 June 2017 at 07:49, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I'm not totally satisfied that there isn't any case where the smallest
> selectivity hack is appropriate.  In the example you're showing here,
> the FK columns are independent so that we get more or less the right
> answer with or without the FK.  But in some quick testing I could not
> produce a counterexample proving that that heuristic is helpful;
> so for now let's can it.
>
> Thanks, and sorry again for the delay.

Many thanks for taking the time on this.

-- David Rowley                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services