Re: BUG #17255: Server crashes in index_delete_sort_cmp() due to race condition with vacuum

Hi,

On 2021-11-12 15:47:45 -0800, Peter Geoghegan wrote:
> On Fri, Nov 12, 2021 at 3:31 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > I wonder if we should try to go for something considerably simpler for 14. How
> > about having a new array that just stores the HTSV state for every
> > ItemIdIsNormal(). For simplicity, we could populate that array eagerly in a
> > separate loop.
>
> Why is that simpler than a boolean array, which represents whether or
> not the item has had its heap_prune_record_unused() call yet (if it's
> a tuple with storage)?

Well, your change is basically a new approach of pruning - a much better
one. But it's a larger change than just eliminating the repeated HTSV calls so
that they cannot change over time. That'd be ~10-15 lines.

> > That'd fix the known bugs, and yield better efficiency (because we'd not
> > re-compute HTSV all the time). Then for HEAD go for something that fixes
> > pruning more fundamentally.
>
> I don't know what you mean about the patch recomputing HTSV all the
> time. The patch doesn't do that.

That was in comparison to HEAD, not your patch.

Greetings,

Andres Freund