Re: BUG #18979: pg_upgrade to PG17 fails if max_slot_wal_keep_size is not set to -1

On Sun, Jul 6, 2025 at 9:41 AM David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
wrote:

> Can't we just move this to postmaster.c ~ line 850 ?
>
> This seems no different than wal_level and summarize_wal having a
> co-dependency such that intermediate invalid states must be allowed to
> exist so long as what the server ends up running under is valid.
> max_slot_wal_keep_size is sighup just like summarize_wal
> (and IsBinaryUpgrade behaves like a postmaster GUC)
>
>
I suppose the answer is because sighup settings seemingly do not belong
here...

./psql postgres
psql (18beta1)
Type "help" for help.

postgres=# show summarize_wal;
summarize_wal
---------------
on
(1 row)

postgres=# show wal_level;
wal_level
-----------
minimal
(1 row)

Which is an impossible combination to begin in but is allowed if you change
only sumamrize_wal to on and perform a reload.

David J.