RE: Synchronizing slots from primary to standby

On Friday, March 15, 2024 10:45 PM Bertrand Drouvot <bertranddrouvot.pg@gmail.com> wrote:
>
> Hi,
>
> On Thu, Mar 14, 2024 at 02:22:44AM +0000, Zhijie Hou (Fujitsu) wrote:
> > Hi,
> >
> > Since the standby_slot_names patch has been committed, I am attaching
> > the last doc patch for review.
> >
>
> Thanks!
>
> 1 ===
>
> +   continue subscribing to publications now on the new primary server
> without
> +   any data loss.
>
> I think "without any data loss" should be re-worded in this context. Data loss in
> the sense "data committed on the primary and not visible on the subscriber in
> case of failover" can still occurs (in case synchronous replication is not used).
>
> 2 ===
>
> +   If the result (<literal>failover_ready</literal>) of both above steps is
> +   true, existing subscriptions will be able to continue without data loss.
> +  </para>
>
> I don't think that's true if synchronous replication is not used. Say,
>
> - synchronous replication is not used
> - primary is not able to reach the standby anymore and standby_slot_names is
> set
> - new data is inserted into the primary
> - then not replicated to subscriber (due to standby_slot_names)
>
> Then I think the both above steps will return true but data would be lost in case
> of failover.

Thanks for the comments, attach the new version patch which reworded the
above places.

Best Regards,
Hou zj