简体中文

UNLISTEN

Stops listening for a notification.

Synopsis

UNLISTEN { <channel> | * }

Description

UNLISTEN is used to remove an existing registration for NOTIFY events. UNLISTEN cancels any existing registration of the current Database session as a listener on the notification channel named channel. The special wildcard * cancels all listener registrations for the current session.

NOTIFY contains a more extensive discussion of the use of LISTEN and NOTIFY.

Parameters

channel
- The name of a notification channel (any identifier).
*
- All current listen registrations for this session are cleared.
  Notes
  
  You can unlisten something you were not listening for; no warning or error will appear.

At the end of each session, UNLISTEN * is automatically executed.

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

Examples

To make a registration:

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

Once UNLISTEN has been executed, further NOTIFY messages will be ignored:

UNLISTEN virtual;
NOTIFY virtual;
-- no NOTIFY event is received

Compatibility

There is no UNLISTEN statement in the SQL standard.