码迷，mamicode.com
首页 > 数据库 > 详细

oracle-常见的执行计划（一）

时间：2016-06-13 01:02:08      阅读：231      评论：0      收藏：0      [点我收藏+]

标签：

一、表访问方式

CBO基础概念中有讲到，访问表的方式有两种：全表扫描和ROWID扫描。

全表扫描的执行计划：TABLE ACCESS FULL

ROWID扫描对应执行计划：TABLE ACCESS BY USER ROWID 或 TABLE ACCESS BY INDEX ROWID

通过例子说明

（一）、全表扫描方式

select empno,ename from scott.emp
      
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  6c0fp61y99tuw, child number 0
-------------------------------------
select empno,ename from scott.emp
 
Plan hash value: 3956160932
 
--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |       |       |     3 (100)|          |
|   1 |  TABLE ACCESS FULL| EMP  |    14 |   140 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------

（二）、rowid访问方式

1、TABLE ACCESS BY USER ROWID

select empno,ename from scott.emp where rowid=‘AAASZHAAEAAAACXAAA‘
  
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  99f9cvxt33nzy, child number 0
-------------------------------------
select empno,ename from scott.emp where rowid=‘AAASZHAAEAAAACXAAA‘
 
Plan hash value: 1116584662
 
-----------------------------------------------------------------------------------
| Id  | Operation                  | Name | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------
|   0 | SELECT STATEMENT           |      |       |       |     1 (100)|          |
|   1 |  TABLE ACCESS BY USER ROWID| EMP  |     1 |    22 |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------

2、TABLE ACCESS BY INDEX ROWID

select empno,ename from scott.emp where empno=7521
  
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  69nxfycyppq7m, child number 0
-------------------------------------
select empno,ename from scott.emp where empno=7521
 
Plan hash value: 2949544139
 
--------------------------------------------------------------------------------------
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |        |       |       |     1 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    10 |     1   (0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | PK_EMP |     1 |       |     0   (0)|          |
--------------------------------------------------------------------------------------
...
 

二、B*树访问方式

索引唯一扫描、索引范围扫描、索引全扫描、索引快速扫描、索引跳跃式扫描

以上这些执行计划执行计划相对应

  • 索引唯一扫描：INDEX UNIQUE SCAN
  • 索引范围扫描：INDEX RANGE SCAN
  • 索引全扫描：INDEX FULL SCAN
  • 索引快速全扫描：INDEX FAST FULL SCAN
  • 索引跳跃式扫描：INDEX SKIP SCAN

例子说明

（一）、索引唯一扫描：INDEX UNIQUE SCAN

select empno,ename from scott.emp where empno=7521
  
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  69nxfycyppq7m, child number 0
-------------------------------------
select empno,ename from scott.emp where empno=7521
 
Plan hash value: 2949544139
 
--------------------------------------------------------------------------------------
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |        |       |       |     1 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |     1 |    10 |     1   (0)| 00:00:01 |
|*  2 |   INDEX UNIQUE SCAN         | PK_EMP |     1 |       |     0   (0)|          |
--------------------------------------------------------------------------------------

通过唯一索引的方式获取rowid访问表中的以rowid的方式

（二）、索引范围扫描：INDEX RANGE SCAN

select empno,ename from scott.emp where empno>=7521 and empno<=8521
  
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  95m0uw0yxc10w, child number 0
-------------------------------------
select empno,ename from scott.emp where empno>=7521 and empno<=8521
 
Plan hash value: 169057108
 
--------------------------------------------------------------------------------------
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |        |       |       |     2 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |    11 |   110 |     2   (0)| 00:00:01 |
|*  2 |   INDEX RANGE SCAN          | PK_EMP |    11 |       |     1   (0)| 00:00:01 |
--------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   2 - access("EMPNO">=7521 AND "EMPNO"<=8521)

谓词中存在大于、小于的访问方式时，并且这个谓词建议过索引，基本采用索引范围扫描的方式

（三）、索引全扫描：INDEX FULL SCAN

select empno,ename from scott.emp order by empno

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  3bt7b5h1rxh6z, child number 0
-------------------------------------
select empno,ename from scott.emp order by empno
 
Plan hash value: 4170700152
 
--------------------------------------------------------------------------------------
| Id  | Operation                   | Name   | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |        |       |       |     2 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP    |    14 |   140 |     2   (0)| 00:00:01 |
|   2 |   INDEX FULL SCAN           | PK_EMP |    14 |       |     1   (0)| 00:00:01 |
--------------------------------------------------------------------------------------

当索引列的定义可以为null

create index ind_EMP_JOB  ON scott.emp(JOB); 
         
select empno,ename from scott.emp order by job
      
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  cnpptzn6mshrb, child number 0
-------------------------------------
select empno,ename from scott.emp order by job
 
Plan hash value: 150391907
 
---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |       |       |     4 (100)|          |
|   1 |  SORT ORDER BY     |      |    14 |   252 |     4  (25)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP  |    14 |   252 |     3   (0)| 00:00:01 |
---------------------------------------------------------------------------

发现如果JOB列定义可以为空的话，order by 是不会走索引的。

调整列的属性，不能为空，在查看执行计划

alter table scott.emp modify(job not null)
          
select empno,ename from scott.emp order by job
      
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  cnpptzn6mshrb, child number 0
-------------------------------------
select empno,ename from scott.emp order by job
 
Plan hash value: 157317628
 
-------------------------------------------------------------------------------------------
| Id  | Operation                   | Name        | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |             |       |       |     2 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP         |    14 |   252 |     2   (0)| 00:00:01 |
|   2 |   INDEX FULL SCAN           | IND_EMP_JOB |    14 |       |     1   (0)| 00:00:01 |
-------------------------------------------------------------------------------------------

（四）、索引快速全扫描：INDEX FAST FULL SCAN

select /*+index_ffs(a ind_EMP_JOB)*/ job  from scott.emp a
      
select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  3hu16hz75qkhu, child number 0
-------------------------------------
select /*+index_ffs(a ind_EMP_JOB)*/ job  from scott.emp a
 
Plan hash value: 2520590889
 
------------------------------------------------------------------------------------
| Id  | Operation            | Name        | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |             |       |       |     2 (100)|          |
|   1 |  INDEX FAST FULL SCAN| IND_EMP_JOB |    14 |   112 |     2   (0)| 00:00:01 |
------------------------------------------------------------------------------------

这里使用HINT，强制提示优化器走fast索引的方式

（五）、索引跳跃式扫描：INDEX SKIP SCAN

用于复合索引中的，非索引前导列的访问

create index ind_EMP_JENAME  ON scott.emp(JOB,ename); 
          
select empno,ename from scott.emp where ename=‘ALLEN‘

SQL_ID  bdfu46xwtg0qk, child number 0
-------------------------------------
select empno,ename from scott.emp where ename=‘ALLEN‘
 
Plan hash value: 878294805
 
----------------------------------------------------------------------------------------------
| Id  | Operation                   | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                |       |       |     2 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID| EMP            |     1 |    10 |     2   (0)| 00:00:01 |
|*  2 |   INDEX SKIP SCAN           | IND_EMP_JENAME |     1 |       |     1   (0)| 00:00:01 |
----------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   2 - access("ENAME"=‘ALLEN‘)
       filter("ENAME"=‘ALLEN‘)

三、位图索引访问的方式

适用于数据仓库，不适用OLTP系统，物理存储结构类似B*数索引，对应rowid的上限、rowid的下限、位图段。

对于oracle数据库中的位图索引而言，他是没有行锁这个概念的，要锁就锁索引行的整个位图段，而多个数据行可能对应同一个索引行的位图段，这个锁的粒度就决定了位图索引不适用于高并发并频繁修改的OLTP系统,在OLTP系统中，很容易产生死锁。

  • 位图索引单键值扫描：BITMAP INDEX SINGLE VALUE
  • 位图索引范围扫描: BITMAP INDEX RANGE SCAN
  • 位图索引全扫描: BITMAP INDEX FULL SCAN
  • 位图索引快速全扫描: BITMAP INDEX FAST FULL SCAN
  • 位图按位与: BITMAP  AND
  • 位图按位或: BITMAP OR
  • 位图按位减: BITMAP MINUS

（一）、构造一张表，测试位图索引

Create table test_normal (empno number(10), ename varchar2(30), sal number(10)) TABLESPACE GLL01;

Begin
For i in 1..1000000
Loop
   Insert into test_normal 
   values(i, dbms_random.string(‘U‘,30), dbms_random.value(1000,7000));
   If mod(i, 10000) = 0 then
   Commit;
  End if;
End loop;
End;

create bitmap index normal_empno_bmx on test_normal(empno) TABLESPACE GLL01;

create bitmap index normal_empno_sal on test_normal(sal) TABLESPACE GLL01;

EXECUTE DBMS_STATS.GATHER_TABLE_STATS(‘SYS‘,‘TEST_NORMAL‘,CASCADE=>TRUE);

（二）、位图索引单键值扫描：BITMAP INDEX SINGLE VALUE

select * from test_normal where empno=1000

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  343wc0yvq4cc9, child number 0
-------------------------------------
select * from test_normal where empno=1000
 
Plan hash value: 4267925254
 
-------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                  |       |       |     3 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID | TEST_NORMAL      |     1 |    40 |     3   (0)| 00:00:01 |
|   2 |   BITMAP CONVERSION TO ROWIDS|                  |       |       |            |          |
|*  3 |    BITMAP INDEX SINGLE VALUE | NORMAL_EMPNO_BMX |       |       |            |          |
-------------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   3 - access("EMPNO"=1000)

（三）、位图索引范围扫描: BITMAP INDEX RANGE SCAN

select * from  test_normal where empno>=50 and  empno<=2000

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  34p69q6q4wqxx, child number 0
-------------------------------------
select * from  test_normal where empno>=50 and  empno<=2000
 
Plan hash value: 641040856
 
-------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                  |       |       |   362 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID | TEST_NORMAL      |  1952 | 78080 |   362   (0)| 00:00:05 |
|   2 |   BITMAP CONVERSION TO ROWIDS|                  |       |       |            |          |
|*  3 |    BITMAP INDEX RANGE SCAN   | NORMAL_EMPNO_BMX |       |       |            |          |
-------------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   3 - access("EMPNO">=50 AND "EMPNO"<=2000)

（四）、位图索引全扫描: BITMAP INDEX FULL SCAN

select /*+index(a normal_empno_bmx)*/  a.empno  from  test_normal a

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  cmxdf5ry1gvw1, child number 0
-------------------------------------
select /*+index(a normal_empno_bmx)*/  a.empno  from  test_normal a
 
Plan hash value: 220257735
 
------------------------------------------------------------------------------------------------
| Id  | Operation                   | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                  |       |       |  3496 (100)|          |
|   1 |  BITMAP CONVERSION TO ROWIDS|                  |  1000K|  4882K|  3496   (1)| 00:00:42 |
|   2 |   BITMAP INDEX FULL SCAN    | NORMAL_EMPNO_BMX |       |       |            |          |
------------------------------------------------------------------------------------------------

（五）、位图索引快速全扫描: BITMAP INDEX FAST FULL SCAN

select /*+index_ffs(a normal_empno_bmx)*/  a.empno  from  test_normal a

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  9rgzkasky186v, child number 0
-------------------------------------
select /*+index_ffs(a normal_empno_bmx)*/  a.empno  from  test_normal a
 
Plan hash value: 2075344169
 
-------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |                  |       |       |  3141 (100)|          |
|   1 |  BITMAP CONVERSION TO ROWIDS |                  |  1000K|  4882K|  3141   (1)| 00:00:38 |
|   2 |   BITMAP INDEX FAST FULL SCAN| NORMAL_EMPNO_BMX |       |       |            |          |
-------------------------------------------------------------------------------------------------

（六）、位图按位与: BITMAP AND、BITMAP OR

select * from  test_normal where empno=3969  and  sal in (1008,1011)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  cyf5th2ts2z7j, child number 0
-------------------------------------
select * from  test_normal where empno=3969  and  sal in (1008,1011)
 
Plan hash value: 640003492
 
--------------------------------------------------------------------------------------------------
| Id  | Operation                     | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT              |                  |       |       |     5 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID  | TEST_NORMAL      |     1 |    40 |     5   (0)| 00:00:01 |
|   2 |   BITMAP CONVERSION TO ROWIDS |                  |       |       |            |          |
|   3 |    BITMAP AND                 |                  |       |       |            |          |
|   4 |     BITMAP OR                 |                  |       |       |            |          |
|*  5 |      BITMAP INDEX SINGLE VALUE| NORMAL_EMPNO_SAL |       |       |            |          |
|*  6 |      BITMAP INDEX SINGLE VALUE| NORMAL_EMPNO_SAL |       |       |            |          |
|*  7 |     BITMAP INDEX SINGLE VALUE | NORMAL_EMPNO_BMX |       |       |            |          |
--------------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   5 - access("SAL"=1008)
   6 - access("SAL"=1011)
   7 - access("EMPNO"=3969)

（七）、位图按位减: BITMAP MINUS

select /*+index_ffs(test_normal normal_empno_sal)*/  * from  test_normal where empno>=50 and  empno<=20000 and  sal not in (1008)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  dn3yq5vrp1524, child number 0
-------------------------------------
select /*+index_ffs(test_normal normal_empno_sal)*/  * from  
test_normal where empno>=50 and  empno<=20000 and  sal not in (1008)
 
Plan hash value: 3977516083
 
--------------------------------------------------------------------------------------------------
| Id  | Operation                     | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT              |                  |       |       |  1385 (100)|          |
|   1 |  TABLE ACCESS BY INDEX ROWID  | TEST_NORMAL      | 19949 |   779K|  1385   (1)| 00:00:17 |
|   2 |   BITMAP CONVERSION TO ROWIDS |                  |       |       |            |          |
|   3 |    BITMAP MINUS               |                  |       |       |            |          |
|   4 |     BITMAP MINUS              |                  |       |       |            |          |
|   5 |      BITMAP MERGE             |                  |       |       |            |          |
|*  6 |       BITMAP INDEX RANGE SCAN | NORMAL_EMPNO_BMX |       |       |            |          |
|*  7 |      BITMAP INDEX SINGLE VALUE| NORMAL_EMPNO_SAL |       |       |            |          |
|*  8 |     BITMAP INDEX SINGLE VALUE | NORMAL_EMPNO_SAL |       |       |            |          |
--------------------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   6 - access("EMPNO">=50 AND "EMPNO"<=20000)
   7 - access("SAL"=1008)
   8 - access("SAL" IS NULL)

列值为NULL，位图索引是记录，以上这个例子中也把列为NULL剔除

 

四、表连接的访问方式

  • 嵌套循环连接：NESTED LOOPS
  • 哈希连接：hash join
  • 排序合并连接：sort join和merge join
  • 反连接：nested loops anti、hash join anti、merge join anti
  • 半连接：nested loop semi、hash join semi、merge join semi

（一）、嵌套循环连接：NESTED LOOPS

select /*+leading(a) use_nl(b)*/* from scott.emp a , scott.dept b  where a.deptno=b.deptno

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  c6xax626nhn8k, child number 0
-------------------------------------
select /*+leading(a) use_nl(b)*/* from scott.emp a , scott.dept b  
where a.deptno=b.deptno
 
Plan hash value: 3625962092
 
----------------------------------------------------------------------------------------
| Id  | Operation                    | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |         |       |       |    17 (100)|          |
|   1 |  NESTED LOOPS                |         |       |       |            |          |
|   2 |   NESTED LOOPS               |         |    14 |   798 |    17   (0)| 00:00:01 |
|   3 |    TABLE ACCESS FULL         | EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|*  4 |    INDEX UNIQUE SCAN         | PK_DEPT |     1 |       |     0   (0)|          |
|   5 |   TABLE ACCESS BY INDEX ROWID| DEPT    |     1 |    19 |     1   (0)| 00:00:01 |
----------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   4 - access("A"."DEPTNO"="B"."DEPTNO")

（二）、哈希连接：hash join

select /*+leading(a) use_hash(b)*/* from scott.emp a , scott.dept b  where a.deptno=b.deptno

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  fq65sryy1d9dw, child number 0
-------------------------------------
select /*+leading(a) use_hash(b)*/* from scott.emp a , scott.dept b  
where a.deptno=b.deptno
 
Plan hash value: 1123238657
 
---------------------------------------------------------------------------
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |      |       |       |     7 (100)|          |
|*  1 |  HASH JOIN         |      |    14 |   798 |     7  (15)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP  |    14 |   532 |     3   (0)| 00:00:01 |
|   3 |   TABLE ACCESS FULL| DEPT |     3 |    57 |     3   (0)| 00:00:01 |
---------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   1 - access("A"."DEPTNO"="B"."DEPTNO")

（三）、排序合并连接：sort join和merge join

select /*+use_merge(a b)*/* from scott.emp a , scott.dept b  where a.deptno=b.deptno

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  9w06suya2pdrn, child number 0
-------------------------------------
select /*+use_merge(a b)*/* from scott.emp a , scott.dept b  where 
a.deptno=b.deptno
 
Plan hash value: 844388907
 
----------------------------------------------------------------------------------------
| Id  | Operation                    | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |         |       |       |     6 (100)|          |
|   1 |  MERGE JOIN                  |         |    14 |   798 |     6  (17)| 00:00:01 |
|   2 |   TABLE ACCESS BY INDEX ROWID| DEPT    |     3 |    57 |     2   (0)| 00:00:01 |
|   3 |    INDEX FULL SCAN           | PK_DEPT |     3 |       |     1   (0)| 00:00:01 |
|*  4 |   SORT JOIN                  |         |    14 |   532 |     4  (25)| 00:00:01 |
|   5 |    TABLE ACCESS FULL         | EMP     |    14 |   532 |     3   (0)| 00:00:01 |
----------------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   4 - access("A"."DEPTNO"="B"."DEPTNO")
       filter("A"."DEPTNO"="B"."DEPTNO")

（四）、反连接：nested loops anti

alter table scott.emp modify(deptno not  null)

select * from scott.emp  a WHERE A.DEPTNO NOT   IN (SELECT  /*+nl_aj*/  DEPTNO FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  dh1c9mwpw9pjx, child number 0
-------------------------------------
select * from scott.emp  a WHERE A.DEPTNO NOT   IN (SELECT  /*+nl_aj*/  
DEPTNO FROM scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 3496123964
 
------------------------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |       |       |     3 (100)|          |
|   1 |  NESTED LOOPS ANTI |         |     7 |   287 |     3   (0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|*  3 |   INDEX UNIQUE SCAN| PK_DEPT |     2 |     6 |     0   (0)|          |
------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   3 - access("A"."DEPTNO"="B"."DEPTNO")

（五）、反连接：hash join anti

select * from scott.emp a WHERE A.DEPTNO NOT  IN (SELECT /*+hash_aj*/    DEPTNO FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  dhq4hhqgqqn0n, child number 0
-------------------------------------
select * from scott.emp a WHERE A.DEPTNO NOT  IN (SELECT /*+hash_aj*/   
 DEPTNO FROM scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 1958379418
 
------------------------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |       |       |     5 (100)|          |
|*  1 |  HASH JOIN ANTI    |         |     7 |   287 |     5  (20)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|   3 |   INDEX FULL SCAN  | PK_DEPT |     3 |     9 |     1   (0)| 00:00:01 |
------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   1 - access("A"."DEPTNO"="B"."DEPTNO")

（六）、反连接：merge join anti

select * from scott.emp  a WHERE A.DEPTNO NOT   IN (SELECT  /*+merge_aj*/  DEPTNO FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  1r60ktudp9vq2, child number 0
-------------------------------------
select * from scott.emp  a WHERE A.DEPTNO NOT   IN (SELECT  
/*+merge_aj*/  DEPTNO FROM scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 4267419248
 
-------------------------------------------------------------------------------
| Id  | Operation           | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT    |         |       |       |     6 (100)|          |
|   1 |  MERGE JOIN ANTI    |         |     7 |   287 |     6  (34)| 00:00:01 |
|   2 |   SORT JOIN         |         |    14 |   532 |     4  (25)| 00:00:01 |
|   3 |    TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|*  4 |   SORT UNIQUE       |         |     3 |     9 |     2  (50)| 00:00:01 |
|   5 |    INDEX FULL SCAN  | PK_DEPT |     3 |     9 |     1   (0)| 00:00:01 |
-------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   4 - access("A"."DEPTNO"="B"."DEPTNO")
       filter("A"."DEPTNO"="B"."DEPTNO")

（七）、半连接：nested loop semi

select * from scott.emp a WHERE  EXISTS (SELECT /*+nl_sj*/  1 FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  9htytj0pxjhkg, child number 0
-------------------------------------
select * from scott.emp a WHERE  EXISTS (SELECT /*+nl_sj*/  1 FROM 
scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 3274513678
 
------------------------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |       |       |     3 (100)|          |
|   1 |  NESTED LOOPS SEMI |         |     7 |   287 |     3   (0)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|*  3 |   INDEX UNIQUE SCAN| PK_DEPT |     2 |     6 |     0   (0)|          |
------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   3 - access("A"."DEPTNO"="B"."DEPTNO")

（八）、半连接：hash join semi

select * from scott.emp a WHERE  EXISTS (SELECT /*+hash_sj*/  1 FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  cjhjgkgs8q1fc, child number 0
-------------------------------------
select * from scott.emp a WHERE  EXISTS (SELECT /*+hash_sj*/  1 FROM 
scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 3753861400
 
------------------------------------------------------------------------------
| Id  | Operation          | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------
|   0 | SELECT STATEMENT   |         |       |       |     5 (100)|          |
|*  1 |  HASH JOIN SEMI    |         |     7 |   287 |     5  (20)| 00:00:01 |
|   2 |   TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|   3 |   INDEX FULL SCAN  | PK_DEPT |     3 |     9 |     1   (0)| 00:00:01 |
------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   1 - access("A"."DEPTNO"="B"."DEPTNO")

（九）、半连接：merge join semi

select * from scott.emp a WHERE  EXISTS (SELECT /*+merge_sj*/  1 FROM scott.dept b where a.deptno=b.deptno)

select *from table(dbms_xplan.display_cursor(null,null))

SQL_ID  f2zxcjpqvpsu5, child number 0
-------------------------------------
select * from scott.emp a WHERE  EXISTS (SELECT /*+merge_sj*/  1 FROM 
scott.dept b where a.deptno=b.deptno)
 
Plan hash value: 3011744318
 
-------------------------------------------------------------------------------
| Id  | Operation           | Name    | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------
|   0 | SELECT STATEMENT    |         |       |       |     6 (100)|          |
|   1 |  MERGE JOIN SEMI    |         |     7 |   287 |     6  (34)| 00:00:01 |
|   2 |   SORT JOIN         |         |    14 |   532 |     4  (25)| 00:00:01 |
|   3 |    TABLE ACCESS FULL| EMP     |    14 |   532 |     3   (0)| 00:00:01 |
|*  4 |   SORT UNIQUE       |         |     3 |     9 |     2  (50)| 00:00:01 |
|   5 |    INDEX FULL SCAN  | PK_DEPT |     3 |     9 |     1   (0)| 00:00:01 |
-------------------------------------------------------------------------------
 
Predicate Information (identified by operation id):
---------------------------------------------------
 
   4 - access("A"."DEPTNO"="B"."DEPTNO")
       filter("A"."DEPTNO"="B"."DEPTNO")

oracle-常见的执行计划（一）

标签：

原文地址：http://www.cnblogs.com/gull/p/5574548.html
踩
(0)
赞
(0)
   
举报
评论 一句话评论（0）
登录后才能评论！
分享档案
更多>
2021年07月29日 (22)
2021年07月28日 (40)
2021年07月27日 (32)
2021年07月26日 (79)
2021年07月23日 (29)
2021年07月22日 (30)
2021年07月21日 (42)
2021年07月20日 (16)
2021年07月19日 (90)
2021年07月16日 (35)
周排行
mamicode.com排行更多图片
更多
友情链接
兰亭集智   国之画   百度统计   站长统计   阿里云   chrome插件   新版天听网
关于我们 - 联系我们 - 留言反馈
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码！