Andrew Fraser DBA

SELECT /*+ parallel(t1 8) pq_distribute(t1 hash hash)
           parallel(t2 8) pq_distribute(t2 hash hash)
           parallel(t3 8) pq_distribute(t3 hash hash)
       */ t1.c1 , t2.c2 , t3.c3
  FROM table1 t1
  JOIN table2 t2 ON t2.table1id = t1.id
  JOIN table3 t3 ON t3.table2id = t2.id
 WHERE ...
;