From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>,
        Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
        Erik Rijkers <er@xs4all.nl>,
        Matthias van de Meent <boekewurm+postgres@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: TRAP: FailedAssertion("HaveRegisteredOrActiveSnapshot()", File: "toast_internals.c", Line: 670, PID: 19403)
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Tue, 19 Apr 2022 07:39:57 -0400"
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Date: Tue, 19 Apr 2022 10:36:36 -0400
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Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Apr 18, 2022 at 4:07 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> There may be some corner cases that aren't described by any of these
>> three blanket scenarios, but they've got to be pretty few and far
>> between.

> My first thought whenever anything like this comes up is cursors,
> especially but not only holdable cursors. Also, plpgsql variables,
> maybe mixed with embedded COMMIT/ROLLBACK.

Those exact cases have had detoasting bugs in the past and are now fixed.

> I don't find it
> particularly hard to believe we have some bugs in
> insufficiently-well-considered parts of the system that pass around
> datums outside of the normal executor flow, but I don't know exactly
> how to find them all, either.

I'm not here to claim that there are precisely zero remaining bugs
of this ilk.  I'm just saying that I think we've flushed out most
of them.  I think there is some value in trying to think of a way
to prove that none remain, but it's not a problem we can solve
for v15.

			regards, tom lane