I wanted to use the parallel hint that would give the best performance in my query which is a equi-join query where the two tables are in a cluster and the join column is a cluster index. I wasn't sure if I should use the parallel option on one of the tables PARALLEL(table1, 4), both of the tables PARALLEL(4) or on the clusters index PARALLEL_INDEX(index_name, 4)? Here was my query:

SELECT /*+ USE_HASH(a, b)  */ a.NAME
FROM Customer a
    ,Sales b
WHERE b.Cust_id < 2000
    AND b.Cust_id = a.Cust_id;

Here is the execution plan for this query:

enter image description here

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