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From: Robert Haas <robertmhaas@gmail.com>
Date: Mon, 8 Sep 2025 14:54:34 -0400
Message-ID: 
 <CA+Tgmobdn8XaV3bCtnbSz-ujLXZhDCn+ygoApp1Wb1f46ixZuQ@mail.gmail.com>
Subject: Re: eliminate xl_heap_visible to reduce WAL (and eventually set VM
 on-access)
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Andres Freund <andres@anarazel.de>,
 Kirill Reshke <reshkekirill@gmail.com>,
	Andrey Borodin <x4mmm@yandex-team.ru>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
 Heikki Linnakangas <hlinnaka@iki.fi>
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On Mon, Sep 8, 2025 at 11:44=E2=80=AFAM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> I pushed this, so rebased v10 is  attached. I've added one new patch:
> 0002 adds ERRCODE_DATA_CORRUPTED to the existing log messages about
> VM/data corruption in vacuum. Andrey Borodin earlier suggested this,
> and I had neglected to include it.

Writing "ereport(WARNING, (errcode(ERRCODE_DATA_CORRUPTED)" is very
much a minority position. Generally the call to errcode() is on the
following line. I think the commit message could use a bit of work,
too. The first sentence heavily duplicates the second and the fourth,
and the third sentence isn't sufficiently well-connected to the rest
to make it clear why you're restating this general principle in this
commit message.

Perhaps something like:

Add error codes when VACUUM discovers VM corruption

Commit fd6ec93bf890314ac694dc8a7f3c45702ecc1bbd and other previous
work has established the principle that when an error is potentially
reachable in case of on-disk corruption, but is not expected to be
reached otherwise, ERRCODE_DATA_CORRUPTED should be used. This allows
log monitoring software to search for evidence of corruption by
filtering on the error code.

That kibitzing aside, I think this is pretty clearly the right thing to do.

--
Robert Haas
EDB: http://www.enterprisedb.com