Re: Replication slots and footguns

Hi,

On 2014-03-12 12:00:25 -0700, Josh Berkus wrote:
> 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?

One with a connected walsender.

> 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?

It's sufficient to terminate the walsender and then drop the slot. That
seems ok for now?

Greetings,

Andres Freund

-- Andres Freund	                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services