PG_ADVISORY_UNLOCK ​

Release an exclusive session-level advisory lock. Multiple lock requests stack; if the same resource is locked three times, it must be unlocked three times to be released for use by other sessions.

PG_ADVISORY_UNLOCK(lock_id)

where lock_id is a BIGINT value.

This function returns a BOOLEAN data type. For example, when a lock is released successfully, the function returns true:

premdb=# select pg_advisory_unlock(32451239);
 pg_advisory_unlock 
--------------------
 t
(1 row)

If a lock with the specified key does not exist, the function returns false:

premdb=# select pg_advisory_unlock(32451240);
WARNING:  you don't own a lock of type ExclusiveLock
 pg_advisory_unlock 
--------------------
 f
(1 row)

Note: Advisory lock functions are not supported in queries with table references in the FROM clause.