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

On Mon, Oct 17, 2022 at 12:23 PM Kyotaro Horiguchi
<horikyota.ntt@gmail.com> wrote:
>
> At Sun, 16 Oct 2022 10:35:17 +0530, Amit Kapila <amit.kapila16@gmail.com> wrote in
> > On Wed, Oct 5, 2022 at 8:54 PM hubert depesz lubaczewski
> > > So, 4 files are missing.
> > >
> > > These were archived properly, and I tried to restore them from archive, and put
> > > them in pg_wal, but even then pg12 was rejecting tries to connect to focal14
> > > slot with the same message about "requested WAL segment
> > > 000000010000CA0A00000049 has already been removed"
> > >
> >
> > I think you are seeing this behavior because we update the
> > lastRemovedSegNo before removing files in RemoveOldXlogFiles() and
> > then we use that to give the error you are seeing.
>
> lastRemovedSegNo is updated once per one segment of removal.  Four
> files are lost in this case.
>

I didn't understand your response. I was saying the one possible
reason why even after restoring files from the archive the error
appears is because of the lastRemovedSegNo related check in function
CheckXLogRemoved() and we update its value while removing old xlog
files. From this behavior, it appears that somehow the server has only
removed those files even though the reason is not clear yet.

-- 
With Regards,
Amit Kapila.