Re: Incorrect result of bitmap heap scan.

On Mon, Dec 2, 2024 at 11:43 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Whether that's true or not, it seems like it'd be worth bisecting
> to see if we can finger a commit where the behavior changed (and
> the same goes for the question of why-isnt-it-an-IOS-scan). However,
> the reproducer seems to have quite a low failure probability for me,
> which makes it hard to do bisection testing with much confidence.
> Can we do anything to make the test more reliable? If I'm right
> to suspect autovacuum, maybe triggering lots of manual vacuums
> would improve the odds?

I agree that autovacuum (actually, VACUUM) is important here.

I find that the test becomes much more reliable if I create the test
table "with (autovacuum_analyze_scale_factor=0.99,
vacuum_truncate=off)". More importantly, rather than relying on
autovacuum, I just run VACUUM manually from psql. I find it convenient
to use "\watch 0.01" to run VACUUM repeatedly.

--
Peter Geoghegan