Re: LISTEN/NOTIFY improvements?

On Thu, 16 Dec 2004, Aaron Hillegass wrote:

> I am a programmer who works on a couple of products that use PostgreSQL
> as their backend (http://www.nopali.com, http://www.iwanttops.com)
> Both my clients need to receive notifications when rows in the database
> change. Thus far, we've been rolling our own because LISTEN/NOTIFY
> doesn't do what we need.
>
> What we need is on the TODO list:
> - Add optional textual message to NOTIFY: This would allow an
> informational message to be added to the notify message, perhaps
> indicating the row modified or other custom information.
>
> I want to help get this done for 8.1, but lack the deep understanding
> necessary. Is there someone on this list that I can beg/bribe to make
> this happen? I would be delighted to do stress-testing and
> benchmarking on the resulting code.
>
> (Incidentally, there are two related TODO items you might want to take
> care of while you are in there:
> - Allow NOTIFY in rules involving conditionals
> - Allow LISTEN/NOTIFY to store info in memory rather than tables?
> Currently LISTEN/NOTIFY information is stored in pg_listener. Storing
> such information in memory would improve performance.)
>
> Regardless, thank you for all the great work that you have been doing;
> PostgreSQL has made my life a better place.

I've got a patch floating around that does this and also moves
LISTEN/NOTIFY into the shared inval code -- which means its faster but
still suffers the problem of relying on a statically sized shared memory
buffer. The point is, I can get the patch into shape without too much
trouble and send it in for 8.1. The great thing is that the patch does not
break the FE/BE protocol because Tom had the foresight to allow optional
messages with NOTIFY events. You legend.

Thanks,

Gavin