Re: POC: enable logical decoding when wal_level = 'replica' without a server restart - Mailing list pgsql-hackers

On Mon, Jun 23, 2025 at 1:41 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> Given the discussion so far, it seems we might want to have a
> safeguard to prevent the effective_wal_level from being dropped to
> 'replica' if the last logical slot is accidentally dropped.

Yes, needed for cases where standby or cascaded standbys have
requirements of logical decoding.

> Another
> idea we can consider is that we automatically increase
> effective_wal_level to 'logical' upon the logical slot creation but
> don't automatically decrease it when dropping the last slot. To
> decrease the effective_wal_level to 'replica', users would need to do
> that explicitly for example using a SQL function,
> pg_disable_logical_decoding().

Okay. Seems a good solution so far.

> We might want to have a GUC parameter
> for users to turn on/off this automatic behavior.
>

Yes. Agreed.

thanks
Shveta