On Thu, Apr 24, 2025 at 11:14 PM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > On Thu, Apr 24, 2025 at 5:30 AM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > > On Wed, Apr 23, 2025 at 9:35 PM Masahiko Sawada <sawada.m...@gmail.com> > > wrote: > > > > > > On Wed, Apr 23, 2025 at 5:46 AM Amit Kapila <amit.kapil...@gmail.com> > > > wrote: > > > > > > > > BTW, did we consider the idea to automatically transition to 'logical' > > > > when the first logical slot is created and transition back to > > > > 'replica' when last logical slot gets dropped? I see some ideas around > > > > this last time we discussed this topic. > > > > > > Yes. Bertrand pointed out that a drawback is that the primary server > > > needs to create a logical slot in order to execute logical decoding on > > > the standbys[1]. > > > > > > > True, but if we want to avoid that, we can still keep 'logical' as > > wal_level for the ease of users. > > I think we'd like to cover the use case like where users start with > 'replica' on the primary and execute logical decoding on the standby > without neither creating a logical slot on the primary nor restarting > the primary. >
Okay, if we introduce a SIGHUP GUC like max_wal_level as you are proposing, the above requirement will be fulfilled, right? The other way is by API pg_activate_logical_decoding(). > > We can also have another API like the > > one you originally proposed (pg_activate_logical_decoding) for the > > ease of users. But the minimum requirement would be that one creates a > > logical slot to enable logical decoding/replication. > > I think we want to avoid the runtime WAL level automatically decreased > to 'replica' once all logical slots are removed, if users still want > to execute logical decoding on only the standby. One idea is that if > users enable logical decoding using pg_activate_logical_decoding(), > the runtime WAL level doesn't decrease to 'replica' even if all > logical slots are removed. > That makes sense. If we are using an API like pg_activate_*/pg_deactivate_*, then why add an additional dependency on the slots? -- With Regards, Amit Kapila.
