(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
pg_get_pid — Gets the backend's process ID
   pg_get_pid() gets the backend's (database server
   process) PID. The PID is useful to determine whether or not a NOTIFY
   message received via pg_get_notify() is sent from another process
   or not.
  
The backend database process ID.
| Version | Description | 
|---|---|
| 8.1.0 | The connectionparameter expects an PgSql\Connection
  instance now; previously, a resource was expected. | 
Example #1 PostgreSQL backend PID
<?php 
$conn = pg_pconnect("dbname=publisher");
if (!$conn) {
  echo "An error occurred.\n";
  exit;
}
// Backend process PID. Use PID with pg_get_notify()
$pid = pg_get_pid($conn);
?>