String 

ALWAYS_ANTI_JOIN = {NESTED_LOOPS | MERGE | HASH} 

Static 

NESTED_LOOPS 

An anti-join returns rows that match a NOT IN subquery. ALWAYS_ANTI_JOIN sets the type of anti-join that Oracle uses. The system verifies that it is legal to perform an anti-join, and if it is, processes the subquery depending on the value of this parameter.  

• NESTED_LOOPS: Oracle uses a nested loop algorithm.

• MERGE: Oracle uses a sort merge algorithm.

• HASH: Oracle uses a hash algorithm to evaluate the subquery. This value allows the evaluation to run in parallel.

See Also: Oracle8i Concepts and Oracle8i Designing and Tuning for Performance for more information on optimizing anti-joins.