From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Jeff Davis <list-pgsql-hackers(at)empires(dot)org> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: listen/notify argument (old topic revisited) |
Date: | 2002-07-02 15:33:13 |
Message-ID: | 200207021533.g62FXDb13077@candle.pha.pa.us |
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Lists: | pgsql-hackers |
Jeff Davis wrote:
> A while ago, I started a small discussion about passing arguments to a NOTIFY
> so that the listening backend could get more information about the event.
>
> There wasn't exactly a consensus from what I understand, but the last thing I
> remember is that someone intended to speed up the notification process by
> storing the events in shared memory segments (IIRC this was Tom's idea). That
> would create a remote possibility of a spurious notification, but the idea is
> that the listening application can check the status and determine what
> happened.
I don't see a huge value to using shared memory. Once we get
auto-vacuum, pg_listener will be fine, and shared memory like SI is just
too hard to get working reliabily because of all the backends
reading/writing in there. We have tables that have the proper sharing
semantics; I think we should use those and hope we get autovacuum soon.
As far as the message, perhaps passing the oid of the pg_listener row to
the backend would help, and then the backend can look up any message for
that oid in pg_listener.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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