谓词推入演示

create or replace view v_emp as select emp.empno,emp.ename,emp.deptno from emp,dept
where emp.deptno=dept.deptno;

SQL> select * from t10;

	ID NAME
---------- ----------
	 1 a
	 2 b
	 3 c
      7902 d
      7900 e
      7844 f

已选择6行。

SQL> select * from v_emp;

     EMPNO ENAME	  DEPTNO
---------- ---------- ----------
      7369 SMITH	      20
      7499 ALLEN	      30
      7521 WARD 	      30
      7566 JONES	      20
      7654 MARTIN	      30
      7698 BLAKE	      30
      7782 CLARK	      10
      7788 SCOTT	      20
      7839 KING 	      10
      7844 TURNER	      30
      7876 ADAMS	      20

     EMPNO ENAME	  DEPTNO
---------- ---------- ----------
      7900 JAMES	      30
      7902 FORD 	      20
      7934 MILLER	      10

已选择14行。

SQL> select  /*+ use_nl(a b)  */ * from t10 a,v_emp b
where a.id=b.empno(+)  2  ;

已选择6行。


执行计划
----------------------------------------------------------
Plan hash value: 1825515217

---------------------------------------------------------------------------------------
| Id  | Operation		     | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT	     |	      |     6 |   228 |     9	(0)| 00:00:01 |
|   1 |  NESTED LOOPS OUTER	     |	      |     6 |   228 |     9	(0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL	     | T10    |     6 |   150 |     3	(0)| 00:00:01 |
|*  3 |   TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    13 |     1	(0)| 00:00:01 |
|*  4 |    INDEX UNIQUE SCAN	     | PK_EMP |     1 |       |     0	(0)| 00:00:01 |
---------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - filter("EMP"."DEPTNO"(+) IS NOT NULL)
   4 - access("A"."ID"="EMP"."EMPNO"(+))

Note
-----
   - dynamic sampling used for this statement (level=2)


统计信息
----------------------------------------------------------
	 11  recursive calls
	  0  db block gets
	 24  consistent gets
	  0  physical reads
	  0  redo size
	837  bytes sent via SQL*Net to client
	415  bytes received via SQL*Net from client
	  2  SQL*Net roundtrips to/from client
	  1  sorts (memory)
	  0  sorts (disk)
	  6  rows processed


SQL> select  /*+ use_nl(a b) no_merge(b)*/ * from t10 a,v_emp b
where a.id=b.empno(+)  2  ;

已选择6行。


执行计划
----------------------------------------------------------
Plan hash value: 3375986511

----------------------------------------------------------------------------------------
| Id  | Operation		      | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT	      |        |     6 |   438 |     9	 (0)| 00:00:01 |
|   1 |  NESTED LOOPS OUTER	      |        |     6 |   438 |     9	 (0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL	      | T10    |     6 |   228 |     3	 (0)| 00:00:01 |
|   3 |   VIEW PUSHED PREDICATE       | V_EMP  |     1 |    35 |     1	 (0)| 00:00:01 |
|*  4 |    TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    13 |     1	 (0)| 00:00:01 |
|*  5 |     INDEX UNIQUE SCAN	      | PK_EMP |     1 |       |     0	 (0)| 00:00:01 |
----------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   4 - filter("EMP"."DEPTNO" IS NOT NULL)
   5 - access("EMP"."EMPNO"="A"."ID")

Note
-----
   - dynamic sampling used for this statement (level=2)


统计信息
----------------------------------------------------------
	 17  recursive calls
	  0  db block gets
	 40  consistent gets
	  0  physical reads
	  0  redo size
	832  bytes sent via SQL*Net to client
	415  bytes received via SQL*Net from client
	  2  SQL*Net roundtrips to/from client
	  1  sorts (memory)
	  0  sorts (disk)
	  6  rows processed

可以看到谓词推入通过关联列推入.