Re: Synchronizing slots from primary to standby

On Thu, Sep 21, 2023 at 9:16 AM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> On Tue, Sep 19, 2023 at 10:29 AM shveta malik <shveta(dot)malik(at)gmail(dot)com> wrote:
>
> Currently in patch001, synchronize_slot_names is a GUC on both primary
> and physical standby. This GUC tells which all logical slots need to
> be synced on physical standbys from the primary. Ideally it should be
> a GUC on physical standby alone and each physical standby should be
> able to communicate the value to the primary (considering the value
> may vary for different physical replicas of the same primary). The
> primary on the other hand should be able to take UNION of these values
> and let the logical walsenders (belonging to the slots in UNION
> synchronize_slots_names) wait for physical standbys for confirmation
> before sending those changes to logical subscribers. The intent is
> logical subscribers should never be ahead of physical standbys.
>

Before getting into the details of 'synchronize_slot_names', I would
like to know whether we really need the second GUC
'standby_slot_names'. Can't we simply allow all the logical wal
senders corresponding to 'synchronize_slot_names' to wait for just the
physical standby(s) (physical slot corresponding to such physical
standby) that have sent ' synchronize_slot_names'list? We should have
one physical standby slot corresponding to one physical standby.

--
With Regards,
Amit Kapila.