Re: implementing NOTIFY with message parameter

Andras Kadinger <bandit@surfnonstop.com> writes:
> ... I therefore invented pg_notify:

Please review the archived discussions about reimplementing NOTIFY using
only shared memory, no tables.  The pg_listener table causes a number of
performance problems, and I think that getting rid of it should be a top
priority if any work is going to get done in that area.  Your proposed
patch would make the performance issues substantially worse by
increasing the volume of dead tuples :-(

Also, any time you are planning new user-visible behavior, it's a good
idea to write the documentation *first*.  In particular I'd like to see
a spec for how this looks to a program using libpq: what is the API for
receiving notify messages with arguments?  Can an empty-string argument
be distinguished from no argument at all?  (Possibly the protocol
prevents that, I'm not sure at the moment.)
        regards, tom lane