Re: Performance of the listen command - Mailing list pgsql-general

From Christopher Browne
Subject Re: Performance of the listen command
Date
Msg-id 87irlfss2g.fsf@wolfe.cbbrowne.com
Whole thread Raw
In response to Performance of the listen command  (Flemming Frandsen <ff@partyticket.net>)
List pgsql-general
The world rejoiced as tgl@sss.pgh.pa.us (Tom Lane) wrote:
> Flemming Frandsen <ff@partyticket.net> writes:
>> I just looked at the pg_listener table:
>> ... and noticed the complete lack of indexen, surely this must be a bug?
>
> No, that was intentional.  It's been a long time but I think the
> argument was that the cost of updating the indexes would outweigh
> their usefulness.  The listen/notify code is really not designed
> for a great deal of "flap" in the set of active listeners :-(
>
> I'm not particularly concerned about trying to add indexes --- would
> much rather get rid of the table approach entirely.  There have been
> prior discussions of this but nothing's been done.

It would be a pretty easy change to add the obvious index; that could
*somewhat* help things for people who use events a lot in the interim.

Consider it stipulated that if lots of NOTIFY requests go through,
that kills a lot of tuples both in table and index...
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