framework/mutex/PgsqlMutex.php
protected function releaseLock($name)
    {
        list($key1, $key2) = $this->getKeysFromName($name);
        return $this->db->useMaster(function ($db) use ($key1, $key2) {
            /** @var \yii\db\Connection $db */
            return (bool) $db->createCommand(
                'SELECT pg_advisory_unlock(:key1, :key2)',
                [':key1' => $key1, ':key2' => $key2]
            )->queryScalar();
        });
    }
protected function releaseLock($name)
    {
        list($key1, $key2) = $this->getKeysFromName($name);
        return $this->db->useMaster(function ($db) use ($key1, $key2) {
            /** @var \yii\db\Connection $db */
            return (bool) $db->createCommand(
                'SELECT pg_advisory_unlock(:key1, :key2)',
                [':key1' => $key1, ':key2' => $key2]
            )->queryScalar();
        });
    }
Releases lock by given name.
@param string $name of the lock to be released.
@return bool release result.
@see http://www.postgresql.org/docs/9.0/static/functions-admin.html