Horton
Menu

Re: [BUG] false positive in bt_index_check in case of short 4B varlena datum

Alexander Korotkov <aekorotkov@gmail.com>

View thread
From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Michael Paquier <michael@paquier.xyz>, Andres Freund <andres@anarazel.de>, Alexander Lakhin <exclusion@gmail.com>, Michael Zhilin <m.zhilin@postgrespro.ru>, pgsql-bugs@postgresql.org, Yura Sokolov <y.sokolov@postgrespro.ru>
Date: 2026-05-12T10:22:59Z
Lists: pgsql-bugs 
On Tue, May 12, 2026 at 12:17 PM Andrey Borodin <x4mmm@yandex-team.ru> wrote:
> > On 9 May 2026, at 04:07, Michael Paquier <michael@paquier.xyz> wrote:
> >
> > On Mon, May 04, 2026 at 10:20:04AM +0500, Andrey Borodin wrote:
> >> However, I'd like to note that (VARSIZE_1B() < TOAST_INDEX_TARGET) is
> >> constantly true for 8Kb+ pages.
> >
> > How much slower?  I cannot imagine that it matters much in this code
> > path, but you are getting me worried.
>
>
> I think there will be no performance difference.
>
> Change proposed by Alexander only prevents use of VARSIZE() against datum
> that is VARSIZE_1B. AFAICS no actual behavior would change.
>
> On some occasions we would have to normilize less tuples.

Any objections if I push and backpatch this?

------
Regards,
Alexander Korotkov
Supabase

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. amcheck: Use correct varlena size accessor in bt_normalize_tuple()