# phpman > man > LISTEN(7)

[LISTEN(7)](https://www.chedong.com/phpMan.php/man/LISTEN/7/markdown)                          PostgreSQL 14.23 Documentation                          [LISTEN(7)](https://www.chedong.com/phpMan.php/man/LISTEN/7/markdown)



## NAME
       LISTEN - listen for a notification

## SYNOPSIS
       LISTEN _channel_

## DESCRIPTION
       **LISTEN** registers the current session as a listener on the notification channel named _channel_.
       If the current session is already registered as a listener for this notification channel,
       nothing is done.

       Whenever the command **NOTIFY** _channel_ is invoked, either by this session or another one
       connected to the same database, all the sessions currently listening on that notification
       channel are notified, and each will in turn notify its connected client application.

       A session can be unregistered for a given notification channel with the **UNLISTEN** command. A
       session's listen registrations are automatically cleared when the session ends.

       The method a client application must use to detect notification events depends on which
       PostgreSQL application programming interface it uses. With the libpq library, the application
       issues **LISTEN** as an ordinary SQL command, and then must periodically call the function
       **PQnotifies** to find out whether any notification 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 documentation for the interface you are using for more details.

## PARAMETERS
       _channel_
           Name of a notification channel (any identifier).

## NOTES
       **LISTEN** takes effect at transaction commit. If **LISTEN** or **UNLISTEN** is executed within a
       transaction that later rolls back, the set of notification channels being listened to is
       unchanged.

       A transaction that has executed **LISTEN** cannot be prepared for two-phase commit.

       There is a race condition when first setting up a listening session: if
       concurrently-committing transactions are sending notify events, exactly which of those will
       the newly listening session receive? The answer is that the session will receive all events
       committed after an instant during the transaction's commit step. But that is slightly later
       than any database state that the transaction could have observed in queries. This leads to
       the following rule for using **LISTEN**: first execute (and commit!) that command, then in a new
       transaction inspect the database state as needed by the application logic, then rely on
       notifications to find out about subsequent changes to the database state. The first few
       received notifications might refer to updates already observed in the initial database
       inspection, but this is usually harmless.

       [**NOTIFY**(7)](https://www.chedong.com/phpMan.php/man/NOTIFY/7/markdown) contains a more extensive discussion of the use of **LISTEN** and **NOTIFY**.

## EXAMPLES
       Configure and execute a listen/notify sequence from psql:

           LISTEN virtual;
           NOTIFY virtual;
           Asynchronous notification "virtual" received from server process with PID 8448.

## COMPATIBILITY
       There is no **LISTEN** statement in the SQL standard.

## SEE ALSO
       [**NOTIFY**(7)](https://www.chedong.com/phpMan.php/man/NOTIFY/7/markdown), [**UNLISTEN**(7)](https://www.chedong.com/phpMan.php/man/UNLISTEN/7/markdown)



PostgreSQL 14.23                                2026                                       [LISTEN(7)](https://www.chedong.com/phpMan.php/man/LISTEN/7/markdown)