Re: Synchronizing slots from primary to standby

On Tue, Feb 27, 2024 at 11:35 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, Feb 27, 2024 at 12:48 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
> >
> > Here are some review comments for v99-0001
> >
> > ==========
> > 0. GENERAL.
> >
> > +#standby_slot_names = '' # streaming replication standby server slot names that
> > + # logical walsender processes will wait for
> >
> > IMO the GUC name is too generic. There is nothing in this name to
> > suggest it has anything to do with logical slot synchronization; that
> > meaning is only found in the accompanying comment -- it would be
> > better if the GUC name itself were more self-explanatory.
> >
> > e.g. Maybe like 'wal_sender_sync_standby_slot_names' or
> > 'wal_sender_standby_slot_names', 'wal_sender_wait_for_standby_slots',
> > or ...
> >
>
> It would be wrong and or misleading to append wal_sender to this GUC
> name as this is used during SQL APIs as well.

Fair enough, but the fact that some SQL functions might wait is also
not mentioned in the config file comment, nor in the documentation for
GUC 'standby_slot_names'. Seems like a docs omission?

> Also, adding wait sounds
> more like a boolean. So, I don't see the proposed names any better
> than the current one.
>

Anyway, the point is that the current GUC name 'standby_slot_names' is
not ideal IMO because it doesn't have enough meaning by itself -- e.g.
you have to read the accompanying comment or documentation to have any
idea of its purpose.

My suggested GUC names were mostly just to get people thinking about
it. Maybe others can come up with better names.

======
Kind Regards,
Peter Smith.
Fujitsu Australia