Re: Questions about Listen/Notify mechanism

Yes, you do have to poll with a "SELECT 1" to get the notifications, this is
very quick and no problem at all,
and you can have lots of LISTEN/NOTIFY without adding much load on the
network, this works very
good so I don't see why you cannot use it.

Mikael

----- Original Message -----
From: "max" <maxbox@directbox.com>
To: <pgsql-jdbc@postgresql.org>
Sent: Sunday, July 18, 2010 4:33 AM
Subject: [JDBC] Questions about Listen/Notify mechanism


> Hallo,
>
> I need to write a Java app which deals with as low as possible network
> resources. That's why the database should inform my Java app about
> changes and I does not have to poll the database every 5 seconds to
> recognize them.
> I read the Postgresql-JDBC documentation about the Listen/Notify
> commands. I do not understand that note
>
> "A key limitation of the JDBC driver is that it cannot receive
> asynchronous notifications and must poll the backend to check if any
> notifications were issued."
>
> Does that mean that the driver will poll the database, e.g. every 5
> seconds? If so, that would not be acceptable for me, because that is
> exactly what I want to avoid. The only advantage of using Listen/Notify
> in that case would be that I don't need an extra notification table that
> my trigger would fill. Am I wrong? Oo
>
> I hope somebody can help me with that.
>
> Regard,
>
> Max
>
>
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