Re: DROP SUBSCRIPTION hangs if sub is disabled in the same transaction

Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:

> On 9/13/17 07:00, Arseny Sher wrote:
>> On the other hand, forbidding to execute disable sub and drop sub in one
>> transaction makes it impossible e.g. to drop subscription in trigger
>
> Disabling a subscription before dropping it isn't very useful, is it?
> So I'm not sure this is an important use case we need to optimize. We
> just need to prevent it from hanging.

Not quite so. Currently it is forbidded to set subscription's slot to
NONE on enabled sub, and the only way to drop sub without touching the
slot is to run ALTER SUBSCRIPTION SET (SLOT_NAME = NONE) beforehand.
Practically this means that we have to go through disable sub -> alter
sub -> drop sub pipeline if we want to left the slot alone or just would
like to drop sub in transaction block -- with replication slot set the
latter is impossible.

--
Arseny Sher