Re: Replication slots and footguns

On 12 March 2014 19:00, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> All:
>
> I was just reading Michael's explanation of replication slots
> (http://michael.otacoo.com/postgresql-2/postgres-9-4-feature-highlight-replication-slots/)
> and realized there was something which had completely escaped me in the
> pre-commit discussion:
>
> select pg_drop_replication_slot('slot_1');
> ERROR: 55006: replication slot "slot_1" is already active
> LOCATION: ReplicationSlotAcquire, slot.c:339
>
> What defines an "active" slot?
>
> It seems like there's no way for a DBA to drop slots from the master if
> it's rapidly running out of disk WAL space without doing a restart, and
> there's no way to drop the slot for a replica which the DBA knows is
> permanently offline but was connected earlier. Am I missing something?

I'm not clear on why would dropping an active replication slot would
solve disk space problems related to WAL. I thought it was inactive
slots that were the problem in this regard?

--
Thom