Re: Listen / Notify - what to do when the queue is full

Joachim Wieland <joe@mcknight.de> writes:
> On Wed, Jan 20, 2010 at 1:05 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I guess Joachim is trying to provide a similar guarantee for the new
>> implementation, but I'm not clear on why it would require locking.

> It is rather about a listening backend seeing a notification in the
> global queue without knowing if it should deliver the notification to
> its frontend or not. The backend needs to know if its own LISTEN
> committed before or after the NOTIFY committed that it sees in the
> queue.

In that case I think you've way overcomplicated matters.  Just deliver
the notification.  We don't really care if the listener gets additional
notifications; the only really bad case would be if it failed to get an
event that was generated after it committed a LISTEN.
        regards, tom lane