Unix/Linux Go Back    

RedHat 9 (Linux i386) - man page for listen (redhat section 7)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)

LISTEN(7)				   SQL Commands 				LISTEN(7)

       LISTEN - listen for a notification

       LISTEN name

       name   Name of notify condition.

       LISTEN Message returned upon successful completion of registration.

       WARNING: Async_Listen: We are already listening on name
	      If this backend is already registered for that notify condition.

       LISTEN  registers  the  current	PostgreSQL  backend as a listener on the notify condition

       Whenever the command NOTIFY name is invoked, either by this backend or  another	one  con-
       nected to the same database, all the backends currently listening on that notify condition
       are notified, and each will in turn notify its connected  frontend  application.  See  the
       discussion of NOTIFY for more information.

       A  backend  can	be  unregistered  for a given notify condition with the UNLISTEN command.
       Also, a backend's listen registrations are automatically cleared when the backend  process

       The  method a frontend application must use to detect notify events depends on which Post-
       greSQL application programming interface it uses. With the libpq library, the  application
       issues  LISTEN  as  an  ordinary  SQL command, and then must periodically call the routine
       PQnotifies to find out whether any notify events have been received. Other interfaces such
       as libpgtcl provide higher-level methods for handling notify events; indeed, with libpgtcl
       the application programmer should not even issue LISTEN or UNLISTEN directly. See the doc-
       umentation for the library you are using for more details.

       NOTIFY [notify(7)] contains a more extensive discussion of the use of LISTEN and NOTIFY.

       name  can  be any string valid as a name; it need not correspond to the name of any actual
       table. If notifyname is enclosed in double-quotes, it need not  even  be  a  syntactically
       valid name, but can be any string up to 63 characters long.

       In  some previous releases of PostgreSQL, name had to be enclosed in double-quotes when it
       did not correspond to any existing table name, even if syntactically valid as a name. That
       is no longer required.

       Configure and execute a listen/notify sequence from psql:

       LISTEN virtual;
       NOTIFY virtual;

       Asynchronous NOTIFY 'virtual' from backend with pid '8448' received.

       There is no LISTEN in SQL92.

SQL - Language Statements		    2002-11-22					LISTEN(7)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums

All times are GMT -4. The time now is 01:46 PM.