Re: NOTIFY/LISTEN in Postgresql

<div class="moz-cite-prefix">On 10/15/2012 02:54 PM, P. Broennimann wrote:<br /></div><blockquote
cite="mid:CACm4aU-eFNaDiYw9uH1n9VPgHN5SqseJ3HqsbgXd7-Cw++NF-g@mail.gmail.com"type="cite"><font face="courier new,
monospace">Hithere</font><div><font face="courier new, monospace"><br /></font></div><div><font face="courier new,
monospace">1)Can a Pg/SQL function "listen" for a notification sent from an external instance?</font></div><div><span
style="font-family:'couriernew',monospace">I would like my stored function to pause/wait and continue its execution
oncean external event (NOTIFY event) occurs.</span></div></blockquote><blockquote
cite="mid:CACm4aU-eFNaDiYw9uH1n9VPgHN5SqseJ3HqsbgXd7-Cw++NF-g@mail.gmail.com"type="cite"><br /><div><font face="courier
new,monospace">2) In </font><span style="font-family:'courier new',monospace">Pg/SQL I can implement a loop (until
somethinghappens) to pause/wait. This costs CPU time -> Is there another solution? Actually I would need something
likea trigger to give my stored function the signal to continue.</span></div></blockquote><br /> Yes. I played around
withthis a while ago, and thought the possibility was beyond cool.<br /> However, after playing around with it and
gettingsome constructive criticism, I decided that it would be better to keep the different application layers
completelyseparated, so that the database layer would not be talking directly to the GUI.<br /><br /> Here is an
examplefunction that I sent to the list a year+ ago.<br /><a
href="http://archives.postgresql.org/pgsql-general/2011-06/msg00322.php">http://archives.postgresql.org/pgsql-general/2011-06/msg00322.php</a><br
/><br/> On the client end, I had something like this:<br /> class ListenThread(threading.Thread):     <br />     def
__init__(self,frame):<br/>         threading.Thread.__init__(self)<br />         self.frame=frame<br />         <br />
   def run(self):<br />             HOST, PORT = "192.168.1.207", 8080<br />         <br />             # Create the
server,binding to localhost on port 8080<br />             server = SocketServer.TCPServer((HOST, PORT),
MyTCPHandler)<br/>             server.frame=self.frame<br />             # Activate the server; this will keep running
untilyou<br />             # interrupt the program with Ctrl-C<br />             server.serve_forever()   <br /><br />