RE: ReplicationSlotRelease() crashes when the instance is in the single user mode

Dear hackers,

Based on the discussion, I feel it is enough to add quick error out for SQL functions. PSA attached.

Best regards,
Hayato Kuroda
FUJITSU LIMITED

> -----Original Message-----
> From: Hayato Kuroda (Fujitsu) <kuroda(dot)hayato(at)fujitsu(dot)com>
> Sent: Tuesday, February 18, 2025 5:24 PM
> To: 'Michael Paquier' <michael(at)paquier(dot)xyz>
> Cc: 'pgsql-hackers(at)lists(dot)postgresql(dot)org' <pgsql-hackers(at)lists(dot)postgresql(dot)org>
> Subject: RE: ReplicationSlotRelease() crashes when the instance is in the single
> user mode
>
> Dear Michael,
>
> > Ah, good point for the slot drop. So 0ce5cf2ef24f is claiming that
> > some of these manipulations are OK. I didn't suspect this one.
>
> Yeah, I think so.
>
> > Slot advancing is a very different beast, unfortunately, that may
> > depend on many other subsystems. For example with logical slots we
> > would finish by calling rm_decode, which could be outside of core.
> > Justifying that this operation is supported in single-user mode is
> > larger than what you are suggesting here..
>
> OK. Actually, I do not have any use-cases in my mind. I played because
> I found a special path for single user mode in ReplicationSlotAcquire()
> so that I wanted to see the behavior.
>
> Best regards,
> Hayato Kuroda
> FUJITSU LIMITED
>
>