On 10/16/2012 07:49 AM, Raghavendra wrote:

On Tue, Oct 16, 2012 at 11:01 AM, Sim Zacks <sim@compulab.co.il> wrote:
On 10/15/2012 06:11 PM, rektide wrote:
Hi pgsql-general,

I'm interested in writing a supervisory process that can insure worker processes are
running/spawn new ones if not. These workers will mainly be responsible for LISTENing to
the db, which is emitting triggered_change_notification s.

Is there any means to check a NOTIFY queue to see who or if anyone is LISTEN ing on it?

Links:
http://www.postgresql.org/docs/9.2/interactive/sql-notify.html
http://www.postgresql.org/docs/9.2/interactive/tcn.html

Regards,
You can look in the pg_listener table. The relname is the Listen/notify code that you call and the listenerpid is the OS pid. You can see more details of that in the pg_stat_activity

Sim

I guess  pg_listener table is deprecated and no longer exist in PG 9.0 onwards. 

--Raghav
I guess I'm dating myself (still on 8.2)
This discussion indicates that it is not possible.
http://archives.postgresql.org/pgsql-hackers/2011-06/msg00016.php