Re: Listen/notify across clusters

On 07/10/2013 09:27 AM, Christopher Browne wrote:
> The act of requesting to LISTEN requires doing a sort of update to the
> database.  In elder versions, it put tuple(s) into pg_catalog.pg_listener,
> and that's Right Well Disallowed on a WAL-based replica.
> 
> I would think that if you're keen on building an "event detection
> substrate," particularly one that's supposed to cross clusters, then you
> should consider using something actually attuned to that, such as a message
> queueing system, whether an AMQP implementation such as RabbitMQ, or a
> message bus like Spread.  If you do that, then you can do this in much
> broader cross-cluster ways for unrelated Postgres clusters.

Huh?  LISTEN/NOTIFY across replication has been a desired feature since
we introduced streaming replication.  We want it, there's just no
obvious way to do it.

Your email kinda implies that it's not desirable.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com