• 휴리스틱 기반의 쿼리 변환 : 특정 조건을 충족시키는 경우 적용
• 비용 기반의 쿼리 변환 : 비용 추정기가 산출한 비용에 근거하여, 원래 실행 계획보다 더 낮은 비용의 실행 계획이 생성될 경우 적용

쿼리 변환 - OR 전개(비용 기반)

----- Current SQL Statement for this session (sql_id=fq3nn8hd5k76r) -----
EXPLAIN PLAN FOR SELECT pad FROM t WHERE n1 = 1 OR n2 = 2
sql_text_length=58
sql=EXPLAIN PLAN FOR SELECT pad FROM t WHERE n1 = 1 OR n2 = 2
----- Explain Plan Dump -----
----- Plan Table -----
 
============
Plan Table
============
------------------------------------------------+-----------------------------------+
| Id  | Operation                     | Name    | Rows  | Bytes | Cost  | Time      |
------------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT              |         |       |       |     4 |           |
| 1   |  CONCATENATION                |         |       |       |       |           |
| 2   |   TABLE ACCESS BY INDEX ROWID | T       |     1 |   111 |     2 |  00:00:01 |
| 3   |    INDEX RANGE SCAN           | I2      |     1 |       |     1 |  00:00:01 |
| 4   |   TABLE ACCESS BY INDEX ROWID | T       |     1 |   111 |     2 |  00:00:01 |
| 5   |    INDEX RANGE SCAN           | I1      |     1 |       |     1 |  00:00:01 |
------------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
3 - access("N2"=2)
4 - filter(LNNVL("N2"=2))
5 - access("N1"=1)

----- Current SQL Statement for this session (sql_id=7jjmgcd6suhyr) -----
EXPLAIN PLAN FOR SELECT pad FROM t WHERE n3 = 3 OR n4 = 4
sql_text_length=58
sql=EXPLAIN PLAN FOR SELECT pad FROM t WHERE n3 = 3 OR n4 = 4
----- Explain Plan Dump -----
----- Plan Table -----
 
============
Plan Table
============
-------------------------------------+-----------------------------------+
| Id  | Operation          | Name    | Rows  | Bytes | Cost  | Time      |
-------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT   |         |       |       |   128 |           |
| 1   |  TABLE ACCESS FULL | T       |  4705 |  492K |   128 |  00:00:01 |
-------------------------------------+-----------------------------------+
Predicate Information:
----------------------
1 - filter(("N3"=3 OR "N4"=4))