Re: LISTEN vs. two-phase commit

Tom Lane wrote:
> Does it make any sense to allow LISTEN or UNLISTEN in a prepared
> transaction?
> ...
>
> Comments?
>

Assuming I understand your question - I don't think of LISTEN or
UNLISTEN as being valuable from a transaction perspective. It's possible
I'm missing something - but I think the transaction overhead, and
attempts to re-use PostgreSQL tables to implement LISTEN/NOTIFY to be
clever but mis-guided. To be practical, LISTEN/NOTIFY should be as fast
as possible, and should never create performance problems, or incur
performance overhead related to transactions.

I had thought of using LISTEN/NOTIFY recently, and upon reading the
threads leading up to this, I was disappointed to hear, and that see for
myself, how asynchronous notify was not immediate within psql, and how
under some circumstances, even with asynchronous notify, it may take a
rather lengthy time before the notify reaches the target. I expect such
notification to be nearly instantaneous, and given this knowledge, I
would choose to use a LISTEN/NOTIFY mechanism outside PostgreSQL for my
next project. Now, does LISTEN/NOTIFY belong outside PostgreSQL in the
first place? I'm not sure...

Cheers,
mark

--
Mark Mielke <mark(at)mielke(dot)cc>