At 07:55 PM 9/22/2010, Vick Khera wrote:
Here's how you do it: first, make sure you are not within a
transaction or other Pg activity. Get the socket's file handle from
the Pg connection handle. When you're ready to wait for a notify
event, just do a select() system call on that file handle waiting
until there is data to read on that socket.
When you return from the select, just check for the notifications and
you're ready to go. If you did not find a notification, return to the
select() call. Of course, this assumes you've issued the necessary
LISTEN command.
This has worked for me (and is tested well) up thru Pg 8.3. I cannot
imagine it would stop working as the wire line protocol doesn't really
change.
How'd one get the socket file handle if using JDBC/ODBC? It seems
possible if using perl DBD-Pg, but I haven't tested that to see if
you can really get out of a transaction.
Given these issues I guess it would be easier to use a separate
messaging server (despite that still not being that easy :) ). This
would have the characteristic of not being DB specific, so apps
wouldn't be locked in to postgresql. Whether this is a benefit or not
depends on your POV ;).
Regards,
Link.
--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
