It is worth to know, that you can set application_name in connection string, consider this simple example:
$appName = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$connStr = "host=localhost port=5432 dbname=postgres user=postgres options='--application_name=$appName'";
$conn = pg_connect($connStr);
$result = pg_query($conn, "select * from pg_stat_activity");
By doing this move on cli or cgi you can see in pgAdmin what scripts are running or what requests are running on database. You can extend configuration of postgres to track slow queries and print application name to logs. It was very usuful to me to find out what and where should I optimize.