PostgreSQL pg_listening_channels() Function
The PostgreSQL pg_listening_channels()
function returns the name of the asynchronous notification channel the current session is listening on.
pg_listening_channels()
Syntax
Here is the syntax of the PostgreSQL pg_listening_channels()
function:
pg_listening_channels() -> boolean
Parameters
The PostgreSQL pg_listening_channels()
function does not require any parameters.
Return value
The PostgreSQL pg_listening_channels()
function returns an array containing the names of the asynchronous notification channels the current session is listening on.
pg_listening_channels()
Examples
The following statements illustrate the pg_listening_channels()
basic usage of PostgreSQL functions:
SELECT pg_listening_channels();
pg_listening_channels
-----------------------
(0 rows)
Here, the current session is not listening to any asynchronous notification channels, so the pg_listening_channels()
function returns an empty result set.
To make the current session listen to an asynchronous notification channel named channel1
, use the following LISTEN
command :
LISTEN channel1;
To make the current session listen to an asynchronous notification channel named channel2
, use the following LISTEN
command :
LISTEN channel2;
To see which asynchronous notification channels the current session is listening on, use the pg_listening_channels()
function:
SELECT pg_listening_channels();
pg_listening_channels
-----------------------
channel1
channel2
(2 rows)
Here, we see that the current session is listening to two asynchronous notification channels: channel1
and channel2
.
If you do not want to continue listening to the channel2
channel , use the following UNLISTEN
command:
UNLISTEN channel2;
To see which asynchronous notification channels the current session is listening on, use the pg_listening_channels()
function:
SELECT pg_listening_channels();
pg_listening_channels
-----------------------
channel1
(1 rows)