Horton

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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Andres Freund <andres@anarazel.de>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-06-25T05:04:58Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix typo in test file name added in commit 4909b38af0.

  2. Fix data loss in logical replication.

  3. Avoid invalidating all RelationSyncCache entries on publication rename.

  4. Remove obsolete RECHECK keyword completely

  5. Backport BackgroundPsql perl test module

On Mon, Jun 24, 2024 at 8:06 PM Tomas Vondra
<tomas.vondra@enterprisedb.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.