On Tue, Feb 17, 2015 at 4:01 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Cory Tucker <cory.tucker@xxxxxxxxx> writes: >> I'm interested in trying to figure out which channels have been subscribed >> to (using LISTEN). From what I could tell via a little Googling, there >> used to be a table named pg_catalog.pg_listener that contained all this >> information, but that seems to have disappeared somewhere in the 9.x >> release (I'm using 9.3.x). > >> Is there a way to find out which channels have listeners? > > No, not any more --- that capability was intentionally given up in the > 9.0 LISTEN/NOTIFY rewrite. Not that it wouldn't be nice to have, but > the cost/benefit ratio was pretty awful. A userland wrapper could probably approximate this: *) create a global id for each channel you want to listen on (basically a table with channel names and a sequence) *) create a function that looks up the id by channel and sharelocks the id with an advisory lock, then listens on it *) the advisory locks will clean themselves up when session ends *) you can scan pg_locks table for type=advisory lock, pid, and the ids of interest to get the data you want merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
