Re: Synchronizing slots from primary to standby

On Tue, Feb 6, 2024 at 1:09 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Tue, Feb 6, 2024 at 3:19 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > I think users can refer to LOGs to see if it has changed since the
> > first time it was configured. I tried by existing parameter and see
> > the following in LOG:
> > LOG: received SIGHUP, reloading configuration files
> > 2024-02-06 11:38:59.069 IST [9240] LOG: parameter "autovacuum" changed to "on"
> >
> > If the user can't confirm then it is better to follow the steps
> > mentioned in the patch. Do you want something else to be written in
> > docs for this? If so, what?
>
> IIUC even if a wrong slot name is specified to standby_slot_names or
> even standby_slot_names is empty, the standby server might not be
> lagging behind the subscribers depending on the timing. But when
> checking it the next time, the standby server might lag behind the
> subscribers. So what I wanted to know is how the user can confirm if a
> failover-enabled subscription is ensured not to go in front of
> failover-candidate standbys (i.e., standbys using the slots listed in
> standby_slot_names).
>

But isn't the same explained by two steps ((a) Firstly, on the
subscriber node check the last replayed WAL. (b) Next, on the standby
server check that the last-received WAL location is ahead of the
replayed WAL location on the subscriber identified above.) in the
latest *_0004 patch.

--
With Regards,
Amit Kapila.