Re: Incorrect result of bitmap heap scan.

On Mon, Dec 2, 2024 at 3:55 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> I suspect one contributor to this avoiding attention till now was that the
> optimization is fairly narrow:
>
> /*
> * We can potentially skip fetching heap pages if we do not need
> * any columns of the table, either for checking non-indexable
> * quals or for returning data. This test is a bit simplistic, as
> * it checks the stronger condition that there's no qual or return
> * tlist at all. But in most cases it's probably not worth working
> * harder than that.
> */
> need_tuples = (node->ss.ps.plan->qual != NIL ||
> node->ss.ps.plan->targetlist != NIL);
>
> Even an entry in the targetlist that that does not depend on the current row
> disables the optimization.

Good point. I agree that that factor is likely to have masked the
problem over the past 6 years.

--
Peter Geoghegan