Re: A recent message added to pg_upgade

On Tue, Jul 8, 2025 at 11:32 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Mon, Jul 7, 2025 at 11:22 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
>
> > There's a bigger picture here, though. The fundamental thing that
> > I find wrong with the current code is that knowledge of and
> > responsibility for this max_slot_wal_keep_size hack is spread across
> > both pg_upgrade and the server. It would be better if it were on
> > just one side. Now, unless we want to change that Assert that
> > 8bfb231b4 put into InvalidatePossiblyObsoleteSlot(), the server side
> > is going to be aware of this decision. So I'm inclined to think
> > that we should silently enforce max_slot_wal_keep_size = -1 in
> > binary-upgrade mode in the server's GUC check hook, and then remove
> > knowledge of it from pg_upgrade altogether. Maybe the same for
> > idle_replication_slot_timeout, which really has got the same issue
> > that we don't want users overriding that choice.
>
> Yeah this change makes sense,
>

Agreed.

One other idea to achieve similar functionality is that during
BinaryUpgrade, avoid removing WAL due to max_slot_wal_keep_size, and
also skip InvalidateObsoleteReplicationSlots. The one advantage of
such a change is that after this, we can remove Assert in
InvalidatePossiblyObsoleteSlot, remove check_hook functions for GUCs
max_slot_wal_keep_size and idle_replication_slot_timeout, and remove
special settings for these GUCs in pg_upgrade.

--
With Regards,
Amit Kapila.