Re: Remove remnants of "snapshot too old" - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Remove remnants of "snapshot too old"
Date
Msg-id 5cewdgo6jo4vblpqet4eukdszom5vevdfdebhnyazb5bbfvib2@u2e4ke5or6cl
Whole thread Raw
Responses Re: Remove remnants of "snapshot too old"
List pgsql-hackers
Hi,

On 2024-12-03 22:06:59 +0200, Heikki Linnakangas wrote:
> I spotted some more remnants of the "snapshot too old" feature that was
> removed in v17. Barring objections, I will commit the attached patch to tidy
> up.

Most of this I agree with. But I'm not sure just removing the toast snapshot
stuff is good - we've had a bunch of bugs where we don't hold a snapshot for
long enough to actually ensure that toast tuples stay alive. It's not legal to
fetch a toast id in one snapshot, release that, and then fetch the toast tuple
with a fresh snapshot.  I think the removal of

> -    if (snapshot == NULL)
> -        elog(ERROR, "cannot fetch toast data without an active snapshot");

will make it easier to introduce further such bugs?

Greetings,

Andres Freund



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