Re: long-standing data loss bug in initial sync of logical replication

On Mon, Jun 24, 2024 at 8:06 PM Tomas Vondra
<tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>
> On 6/24/24 12:54, Amit Kapila wrote:
> > ...
> >>
> >>>> I'm not sure there are any cases where using SRE instead of AE would cause
> >>>> problems for logical decoding, but it seems very hard to prove. I'd be very
> >>>> surprised if just using SRE would not lead to corrupted cache contents in some
> >>>> situations. The cases where a lower lock level is ok are ones where we just
> >>>> don't care that the cache is coherent in that moment.
> >>
> >>> Are you saying it might break cases that are not corrupted now? How
> >>> could obtaining a stronger lock have such effect?
> >>
> >> No, I mean that I don't know if using SRE instead of AE would have negative
> >> consequences for logical decoding. I.e. whether, from a logical decoding POV,
> >> it'd suffice to increase the lock level to just SRE instead of AE.
> >>
> >> Since I don't see how it'd be correct otherwise, it's kind of a moot question.
> >>
> >
> > We lost track of this thread and the bug is still open. IIUC, the
> > conclusion is to use SRE in OpenTableList() to fix the reported issue.
> > Andres, Tomas, please let me know if my understanding is wrong,
> > otherwise, let's proceed and fix this issue.
> >
>
> It's in the commitfest [https://commitfest.postgresql.org/48/4766/] so I
> don't think we 'lost track' of it, but it's true we haven't done much
> progress recently.
>

Okay, thanks for pointing to the CF entry. Would you like to take care
of this? Are you seeing anything more than the simple fix to use SRE
in OpenTableList()?

--
With Regards,
Amit Kapila.