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 Greengage DB 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
| Parameter | Description |
|---|---|
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
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 receivedCompatibility
There is no UNLISTEN statement in the SQL standard.