Thread

1. Listen and notify in psql process

   Sakshi Jain <sakshijain10388@gmail.com> — 2021-06-17T11:01:41Z

   Hi Team,
   
   How to listen from within a psql process and get the payloads?
   
   Do Postgres have any such a mechanism where in a session a process send a
   "listen <name>" sql command and then gets a message if someone in the other
   session issued a "notify <name>".
   
   Please provide an example of how to do this.
   
   -- 
   *Thanks & Regards*
   Sakshi Jain
   New Delhi
   8882433263
   

2. Fwd: Listen and notify in psql process

   Sakshi Jain <sakshijain10388@gmail.com> — 2021-06-17T11:04:27Z

   Hi Team,
   
   How to listen from within a psql process and get the payloads?
   
   Do Postgresql have any such a mechanism where in a session a process send a
   "listen <name>" sql command and then gets a message if someone in the other
   session issued a "notify <name>".
   
   Please provide an example of how to do this.
   
   I am looking for listen to return some thing when a notify has been issued.
   
   -- 
   *Thanks & Regards*
   Sakshi Jain
   New Delhi
   8882433263
   
   
   
   -- 
   *Thanks & Regards*
   Sakshi Jain
   New Delhi
   8882433263
   

3. Re: Listen and notify in psql process

   Ravi Krishna <srkrishna@yahoo.com> — 2021-06-17T11:45:27Z

   https://www.postgresql.org/docs/current/sql-notify.html
   
   https://www.postgresql.org/docs/13/sql-listen.html
   
   
     

4. Re: Listen and notify in psql process

   Torsten Förtsch <tfoertsch123@gmail.com> — 2021-06-17T13:34:05Z

   On Thu, Jun 17, 2021 at 1:04 PM Sakshi Jain <sakshijain10388@gmail.com>
   wrote:
   
   How to listen from within a psql process and get the payloads?
   >
   > Do Postgresql have any such a mechanism where in a session a process send
   > a "listen <name>" sql command and then gets a message if someone in the
   > other session issued a "notify <name>".
   >
   > Please provide an example of how to do this.
   >
   > I am looking for listen to return some thing when a notify has been issued.
   >
   
   Here is an example in perl. Basically you issue the LISTEN command. Then
   you sit and watch the file descriptor to become ready. You do that outside
   of a transaction. Once the descriptor is ready you call your driver's
   version of notification read function until it comes back empty. That is
   when you go back and wait for the next arrival.
   
   $dbh->do("LISTEN channel");
   my $sel = IO::Select->new;
   $sel->add($dbh->{pg_socket});
   while ($sel->can_read) {
       while (my $notify = $dbh->pg_notifies) {
           my ($name, $pid, $payload) = @$notify;
           do_something($payload);
       }
   }
   
   >
   

5. Re: Listen and notify in psql process

   Erik Brandsberg <erik@heimdalldata.com> — 2021-06-17T14:22:34Z

   Google for Postgres listen notify... ;)  It is in the documentation.
   
   On Thu, Jun 17, 2021 at 7:02 AM Sakshi Jain <sakshijain10388@gmail.com>
   wrote:
   
   > Hi Team,
   >
   > How to listen from within a psql process and get the payloads?
   >
   > Do Postgres have any such a mechanism where in a session a process send a
   > "listen <name>" sql command and then gets a message if someone in the other
   > session issued a "notify <name>".
   >
   > Please provide an example of how to do this.
   >
   > --
   > *Thanks & Regards*
   > Sakshi Jain
   > New Delhi
   > 8882433263
   >
   >
   
   
   -- 
   *Erik Brandsberg*
   erik@heimdalldata.com
   
   www.heimdalldata.com
   +1 (866) 433-2824 x 700
   [image: AWS Competency Program]
   <https://aws.amazon.com/partners/find/partnerdetails/?n=Heimdall%20Data&id=001E000001d9pndIAA>