Re: New standby_slot_names GUC in PG 17

On Tue, Jun 25, 2024 at 1:54 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, Jun 25, 2024 at 8:20 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > On Tue, Jun 25, 2024 at 11:21 AM Zhijie Hou (Fujitsu)
> > <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > >
> > > I agree the current name seems too generic and the suggested ' synchronized_standby_slots '
> > > is better than the current one.
> > >
> > > Some other ideas could be:
> > >
> > > synchronize_slots_on_standbys: it indicates that the standbys that enabled
> > > slot sync should be listed in this GUC.
> > >
> > > logical_replication_wait_slots: it means the logical replication(logical
> > > Walsender process) will wait for these slots to advance the confirm flush
> > > lsn before proceeding.
> >
> > I feel that the name that has some connection to "logical replication"
> > also sounds good. Let me add some ideas:
> >
> > - logical_replication_synchronous_standby_slots (might be too long)
> > - logical_replication_synchronous_slots
> >
>
> I see your point about keeping logical_replication in the name but
> that could also lead one to think that this list can contain logical
> slots.

Right.

> OTOH, there is some value in keeping '_standby_' in the name as
> that is more closely associated with physical standby's and this list
> contains physical slots corresponding to physical standby's.

Agreed.

> So, my
> preference is in order as follows: synchronized_standby_slots,
> wait_for_standby_slots, logical_replication_wait_slots,
> logical_replication_synchronous_slots, and
> logical_replication_synchronous_standby_slots.

I also prefer synchronized_standby_slots.

From a different angle just for discussion, is it worth considering
the term 'failover' since the purpose of this feature is to ensure a
standby to be ready for failover in terms of logical replication? For
example, failover_standby_slot_names?

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com