Re: Possible G2-item at SERIALIZABLE

> On 2 Jun 2026, at 03:00, Zsolt Parragi <zsolt(dot)parragi(at)percona(dot)com> wrote:
>
> + /*
> + * Mark ourselves doomed before raising the error. Otherwise a
> + * subtransaction abort (ROLLBACK TO SAVEPOINT) could swallow this
> + * error and let the transaction commit anyway, defeating SSI.
> + */
> + MySerializableXact->flags |= SXACT_FLAG_DOOMED;
> LWLockRelease(SerializableXactHashLock);
> ereport(ERROR,
> (errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
>
> I wonder if it would make sense to introduce a
> "DoomMyselfAndRaiseSerializationFailure" helper for this, while fixing
> all occurrences we can find? That would make it more explicit, and
> also less repeated.
>
>> PFA attached isolation tester and hand-wavy fix. But I suspect there are more G-items
>> around.
>
> There are at least 2 more reproducible with the isolation tester in
> CheckForSerializableConflictOut ("conflict out to old pivot %u", and
> "conflict out to old committed transaction %u" directly below it).
> Probably "Canceled on conflict out to old pivot." also should have the
> same changes?

Thanks for looking into this!
I agree fix needs some refinement and can be improved.

However, let's settle on the bug first.
Do you think that recovering serialization error with ROLLBACK TO SAVEPOINT is a bug?

Honestly, I'm not entirely convinced myself. AFAIU SSI docs do not describe this case
clearly.

Best regards, Andrey Borodin.