CREATE TABLE mytable
(
        id1        INTEGER NOT NULL,
        id2        INTEGER NOT NULL,
        value          INTEGER NOT NULL,
        PRIMARY KEY(id1, id2),
        FOREIGN KEY(id1) REFERENCES another_table(id) ON DELETE CASCADE,
        FOREIGN KEY(id2) REFERENCES users(id) ON DELETE CASCADE
);

select * from pg_locks;
   locktype    | database | relation | page | tuple | transactionid | classid | objid | objsubid | transaction |  pid  |      mode       | granted
---------------+----------+----------+------+-------+---------------+---------+-------+----------+-------------+-------+-----------------+---------
 transactionid |          |          |      |       |       13853943  |         |       |          |     13853943  |  10000  | ExclusiveLock   | t
 relation      |     16384  |     10342  |      |       |               |         |       |          |     13853943  |  10000  | AccessShareLock | t
( 2  rows)