Re: pgsql: Prevent invalidation of newly synced replication slots.

On Tue, Jan 27, 2026 at 11:46 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Tue, Jan 27, 2026 at 12:42 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > 2026-01-27 17:19:25.354 GMT startup[2488] DEBUG: didn't need to
> > unlink permanent stats file "pg_stat/pgstat.stat" - didn't exist
> > 2026-01-27 17:19:38.938 GMT startup[2488] FATAL: could not rename
> > file "backup_label" to "backup_label.old": Permission denied
>
> Andrey Borodin pointed out to me off-list that there's a retry loop in
> pgrename(). The 13 second delay between the above two log messages
> almost certainly means that retry loop is iterating until it hits its
> 10 second timeout.
>

Yes, this is correct. I am able to reproduce it. In pgrename(), we use
MoveFileEx() windows API which fails with errorcode 32 which further
maps to doserrr 13 via _dosmaperr. It is following mapping
ERROR_SHARING_VIOLATION, EACCES in doserrors struct.

This almost certainly means that the underlying
> Windows error is ERROR_ACCESS_DENIED, ERROR_SHARING_VIOLATION, or
> ERROR_LOCK_VIOLATION, and that somebody else has the file open.
>

It is ERROR_SHARING_VIOLATION.

But
> nothing other than Perl touches that directory before we try to start
> the standby:
>
> my $standby = PostgreSQL::Test::Cluster->new('standby');
> $standby->init_from_backup(
> $primary, $backup_name,
> has_streaming => 1,
> has_restoring => 1);
> $standby->append_conf(
> 'postgresql.conf', qq(
> hot_standby_feedback = on
> primary_slot_name = 'phys_slot'
> primary_conninfo = '$connstr_1 dbname=postgres'
> log_min_messages = 'debug2'
> ));
> $standby->start;
>
> As far as I can see, only init_from_backup() touches the backup_label
> file, and that just copies the directory using RecursiveCopy.pm, which
> as far as I can tell is quite careful about closing file handles. So I
> still have no idea what's happening here.
>

It is not clear to me either why the similar test like
040_standby_failover_slots_sync is successful and
046_checkpoint_logical_slot is failing. I am still thinking about it
but thought of sharing the information I could gather by debugging.

Do let me know if you could think of gathering any other information
which can be of help here.

--
With Regards,
Amit Kapila.