CREATE OR REPLACE FUNCTION synchronize()
RETURNS trigger AS
$$
    import psycopg2

    conn = psycopg2.connect("host=... dbname=... user=... password=...")
    cur = conn.cursor()

    # If inserting...
    if TD['event'] == 'INSERT':
      cur.execute(...)

    # If deleting...
    if TD['event'] == 'DELETE':
      cur.execute(...)

    conn.commit()
    cur.close()
    conn.close()
$$
LANGUAGE 'plpython2u' VOLATILE;

CREATE TRIGGER replica_insert
AFTER INSERT ON users
FOR EACH ROW
EXECUTE PROCEDURE synchronize();

CREATE TRIGGER replica_delete
BEFORE DELETE ON users
FOR EACH ROW
EXECUTE PROCEDURE synchronize();