Horton

Re: WAL segments removed from primary despite the fact that logical replication slot needs it.

hubert depesz lubaczewski <depesz@depesz.com>

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From: hubert depesz lubaczewski <depesz@depesz.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: pgsql-bugs mailing list <pgsql-bugs@postgresql.org>
Date: 2022-10-19T11:11:06Z
Lists: pgsql-bugs

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  1. Fix a possibility of logical replication slot's restart_lsn going backwards.

On Tue, Oct 18, 2022 at 04:57:52PM +0530, Amit Kapila wrote:
> On Mon, Oct 17, 2022 at 2:43 PM hubert depesz lubaczewski
> <depesz@depesz.com> wrote:
> >
> > On Sun, Oct 16, 2022 at 10:35:17AM +0530, Amit Kapila wrote:
> > > > Wal file has been removed. Please note that the file was, as shown earlier, still within "restart_lsn" as visibile on pg12/bionic.
> > > This is quite strange and I am not able to see the reason why this can
> > > happen. The only way to debug this problem that comes to mind is to
> > > add more LOGS around the code that removes the WAL files. For example,
> > > we can try to print the value of minimumslotLSN (keep) and logSegNo in
> > > KeepLogSeg().
> >
> > That would require changing pg sources, I think, recompiling, and
> > retrying?
> >
> 
> Yes. BTW, are you on the latest release of pg12, if not then you can
> once check the release notes to see if there is any related bug fix in
> the later releases?

We're not. We're on 12.9, and there seem to be some wal-related changes
since then:
https://why-upgrade.depesz.com/show?from=12.9&to=12.12&keywords=wal*

will talk with responsible people about upgrading it, and then redoing
the test.

Best regards,

depesz