Used as intermediate step in a MERGE JOIN
This operation is implemented in the following versions
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This example was developed using Oracle 9.2.0.1 on Windows 2000
This example requires the following table definition
CREATE TABLE t1 (c1 NUMBER);
The table does not need to be analysed
The statement
SELECT /*+ USE_MERGE (t1 t2) */ t1.c2,t2.c2 FROM t1,t2 WHERE t1.c1 = t2.c1;
generates the following execution plan
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 MERGE JOIN 2 1 SORT (JOIN) 3 2 TABLE ACCESS (FULL) OF 'T1' 4 1 SORT (JOIN) 5 4 TABLE ACCESS (FULL) OF 'T2'