How Can We Tune the Joins with "OR" Caluse ?

Question

Hi
We've identified one Query in one of Our PL/SQL Stored Procedure which is taking huge time to fetch the records. I have simulated the problem as shown below. The problem Is, How can i tune the Jions with "OR" Clause. i have tried replacing them with Exists Caluse, But the Performance was not much was expected.
CREATE TABLE TEST
(ID NUMBER VDATE DATE );
BEGIN
  FOR i IN 1 .. 100000 LOOP
    INSERT INTO TEST
    VALUES
      (i, TO_DATE(TRUNC(DBMS_RANDOM.VALUE(2452641, 2452641 + 364)), 'J'));
    IF MOD(i, 1000) = 0 THEN
      COMMIT;
    END IF;
  END LOOP;
END;
CREATE TABLE RTEST1 ( ID NUMBER, VMONTH NUMBER );
INSERT INTO RTEST1
SELECT ID, TO_NUMBER(TO_CHAR(VDATE,'MM'))
FROM TEST ;
CREATE TABLE RTEST2 ( ID NUMBER, VMONTH NUMBER );
INSERT INTO RTEST2
SELECT ID, TO_NUMBER(TO_CHAR(VDATE,'MM'))
FROM TEST;
CREATE INDEX RTEST1_IDX2 ON RTEST1(VMONTH)
CREATE INDEX RTEST2_IDX1 ON RTEST2(VMONTH)
ALTER TABLE RTEST1 ADD CONSTRAINT RTEST1_PK  PRIMARY KEY (ID)
ALTER TABLE RTEST2 ADD CONSTRAINT RTEST2_PK  PRIMARY KEY (ID)
SELECT A.ID, B.VMONTH
FROM RTEST1 A , RTEST2 B
WHERE A.ID = B.ID  
AND ( (A.ID = B.VMONTH) OR ( B.ID = A.VMONTH ) )  
BEGIN
DBMS_STATS.gather_table_stats(ownname => 'PHASE30DEV',tabname => 'RTEST1');  
DBMS_STATS.gather_table_stats(ownname => 'PHASE30DEV',tabname => 'RTEST2');
DBMS_STATS.gather_index_stats(ownname => 'PHASE30DEV',indname => 'RTEST1_IDX1');
DBMS_STATS.gather_index_stats(ownname => 'PHASE30DEV',indname => 'RTEST2_IDX2');
DBMS_STATS.gather_index_stats(ownname => 'PHASE30DEV',indname => 'RTEST1_IDX2');
DBMS_STATS.gather_index_stats(ownname => 'PHASE30DEV',indname => 'RTEST2_IDX1');
END; Pls suggest !!!!!!! How can I tune the Joins with "OR" Clause.
Regards
RJ

Answer 1

I don't like it, but you could use a hint:
SQL>r
  1  SELECT A.ID, B.VMONTH
  2  FROM RTEST1 A , RTEST2 B
  3  WHERE A.ID = B.ID
  4* AND ( (A.ID = B.VMONTH) OR ( B.ID = A.VMONTH ) )
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=94 Card=2 Bytes=28)
   1    0   TABLE ACCESS (BY INDEX ROWID) OF 'RTEST2' (Cost=94 Card=1 Bytes=7)
   2    1     NESTED LOOPS (Cost=94 Card=2 Bytes=28)
   3    2       TABLE ACCESS (FULL) OF 'RTEST1' (Cost=20 Card=100000 Bytes=700000)
   4    2       BITMAP CONVERSION (TO ROWIDS)
   5    4         BITMAP AND
   6    5           BITMAP CONVERSION (FROM ROWIDS)
   7    6             INDEX (RANGE SCAN) OF 'RTEST2_PK' (UNIQUE)
   8    5           BITMAP OR
   9    8             BITMAP CONVERSION (FROM ROWIDS)
  10    9               INDEX (RANGE SCAN) OF 'RTEST2_IDX1' (NON-UNIQUE)
  11    8             BITMAP CONVERSION (FROM ROWIDS)
  12   11               INDEX (RANGE SCAN) OF 'RTEST2_PK' (UNIQUE)
Statistics
          0  recursive calls
          0  db block gets
     300332  consistent gets
          0  physical reads
          0  redo size
        252  bytes sent via SQL*Net to client
        235  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          2  rows processed
SQL>SELECT /*+ ordered use_hash(b) */ A.ID, B.VMONTH
  2    FROM RTEST1 A, RTEST2 B
  3   WHERE A.ID = B.ID  AND(A.ID = B.VMONTH OR B.ID = A.VMONTH)
  4  ;
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=175 Card=2 Bytes=28)
   1    0   HASH JOIN (Cost=175 Card=2 Bytes=28)
   2    1     TABLE ACCESS (FULL) OF 'RTEST1' (Cost=20 Card=100000 Bytes=700000)
   3    1     TABLE ACCESS (FULL) OF 'RTEST2' (Cost=20 Card=100000 Bytes=700000)
Statistics
          9  recursive calls
          0  db block gets
        256  consistent gets
        156  physical reads
          0  redo size
        252  bytes sent via SQL*Net to client
        235  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          2  rows processed