Nested loops join, hash join, sort merge Join (2015-2-4 learning Diary)

==>> nested loops Join, hash join, sort merge Join

-->> Nested Loops Join

SELECT * from/*+leading (t1) use_nl (T2) */from T1,T2

where t1.id=t2.t1_id;

The meaning of this hint: leading (t1) means that forcing the first access to the table T1,USE_NL means forcing the use of nested loops.

-->> Hash Connection

SELECT * from/*+leading (t1) use_hash (T2) */from T1,T2

where t1.id=t2.t1_id;

-->> Sort Merge Connections

Select/*+orderd use_merge (T2) */* from T1,T2

where t1.id=t2.t1_id;

The sort merge connection is not driven with the concept of being driven.

Nested loops join, hash join, sort merge Join (2015-2-4 learning Diary)