From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | "Andreas 'ads' Scherbaum" <adsmail(at)wars-nicht(dot)de>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Feature request: NOTIFY enhancement |
Date: | 2008-01-03 18:47:56 |
Message-ID: | 200801031847.m03Iluq25416@momjian.us |
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Lists: | pgsql-general |
Alvaro Herrera wrote:
> Andreas 'ads' Scherbaum wrote:
>
> > It is possible, that some notifies, if following in a very short time
> > frame, can get lost.
> >
> > In case we want to send extra text messages with NOTIFY, we should make
> > sure, that no notify get lost.
>
> Right. Currently, NOTIFY acts like Unix signals -- consecutive signals
> can get "collapsed" into a single one, and the listening process is
> responsible for ensuring that it gets the communication details from
> elsewhere.
>
> If the idea is to convert NOTIFY into a full-blown communication system,
> then no collapsing can take place. This means the additional data
> (which can be of unbounded size) must be stored elsewhere, probably on
> disk.
>
> So far (AFAIK), the only detailed design proposal came from Neil Conway,
> which used SLRU for storage, but AFAIK he didn't take it much further.
TODO has:
* 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.
I have added this to TODO:
* Allow multiple identical NOTIFY events to always be communicated to the
client, rather than sent as a single notification to the listener
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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