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From: Peter Geoghegan <pg@bowt.ie>
Date: Sat, 26 Apr 2025 23:53:08 -0400
Message-ID: 
 <CAH2-Wz=1eJZMSMoACDW2oLcxd8QUtKQS7HuYtqx98LLji+WKuQ@mail.gmail.com>
Subject: Re: pgsql: Improve nbtree skip scan primitive scan scheduling.
To: Mark Dilger <mark.dilger@enterprisedb.com>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>,
 pgsql-committers@lists.postgresql.org
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On Sat, Apr 26, 2025 at 10:39=E2=80=AFPM Mark Dilger
<mark.dilger@enterprisedb.com> wrote:
> Peter, Matthias, thanks kindly for the good work on skipscans!

Thanks!

> I found a test case which fails after commit 21a152b37f36c9563d1b0b058fe1=
436baf578b4c.  Please find a reproducible test case, attached.

The bug isn't actually in commit
21a152b37f36c9563d1b0b058fe1436baf578b4c -- it's just an accident that
the mechanism added by that commit happens to make your test case
fail. The underlying issue was introduced in commit 8a510275, "Further
optimize nbtree search scan key comparisons".

This looks to have been a silly oversight in our handling of NULL
tuple datums within _bt_check_compare. Attached provisional fix makes
your test case pass.

--=20
Peter Geoghegan

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