oracle查看执行计划之DBMS_XPLAN

使用DBMS_XPLAN包中的方法是在oracle数据库中得到目标SQL的执行计划的另一种方法。针对不同的应用场景吗，你可以选择如下四种方法中的一种：

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select * from table(dbms_xplan.display)

select * from table(dbms_xplan.display_cursor(null,null,'advenced'));

select * from table(dbms_xplan.display_cursor('sql_id/hash_value',child_cursor_number,'advanced'));

select * from table(dbms_xplan.display_awr('sql_id'));

方法1是执行select * from table(dbms_xplan.display)，这需要与explain plan命令配合使用，它用于查看使用explain plan命令后得到的执行计划。

方法2是执行select * from table(dbms_xplan.display_cursor(null,null,'advenced'));它用于查看刚刚执行过的sql的执行计划，这里针对dbms_xplan.display_cursor所传入的第一个和第二参数的值均为null，第三参数的值是“advanced”，第三个输入参数的值也可以是“all”，只不过用“advanced”后的显示结果会比用“all”的显示结果更详细些。

SQL> conn scott/scott;

Connected.

SQL> set linesize 800

SQL> set pagesize 900

SQL> col plan_table_output for a200

SQL> select empno,ename,dname from emp,dept where emp.deptno=dept.deptno;

EMPNO ENAME DNAME

---------- ---------- --------------

7782 CLARK ACCOUNTING

7839 KING ACCOUNTING14 rows selected.

SQL> select * from table(dbms_xplan.display_cursor(null,null,'advanced'));

PLAN_TABLE_OUTPUT

-------------------------------------------------------------------------------------------

SQL_ID7ww0fhpbqqt0n, child number 0

-------------------------------------

select empno,ename,dname from emp,dept where emp.deptno=dept.deptno

Plan hash value: 844388907

----------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | | | 6 (100)| |

| 1 | MERGE JOIN | | 14 | 364 | 6(17)| 00:00:01 |

| 2 | TABLE ACCESS BY INDEX ROWID| DEPT | 4 | 52 | 2 (0)| 00:00:01 |

| 3 | INDEX FULL SCAN | PK_DEPT | 4 | | 1 (0)| 00:00:01 |

|* 4 | SORT JOIN | | 14 | 182 | 4(25)| 00:00:01 |

| 5 | TABLE ACCESS FULL | EMP | 14 | 182 | 3 (0)| 00:00:01 |

----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):

-------------------------------------------------------------

1 - SEL$1

2 - SEL$1 / DEPT@SEL$1

3 - SEL$1 / DEPT@SEL$1

5 - SEL$1 / EMP@SEL$1

Outline Data

-------------

/*+

BEGIN_OUTLINE_DATA

IGNORE_OPTIM_EMBEDDED_HINTS

OPTIMIZER_FEATURES_ENABLE('11.2.0.4')

DB_VERSION('11.2.0.4')

ALL_ROWS

OUTLINE_LEAF(@"SEL$1")

INDEX(@"SEL$1" "DEPT"@"SEL$1" ("DEPT"."DEPTNO"))

FULL(@"SEL$1" "EMP"@"SEL$1")

LEADING(@"SEL$1" "DEPT"@"SEL$1" "EMP"@"SEL$1")

USE_MERGE(@"SEL$1" "EMP"@"SEL$1")

END_OUTLINE_DATA

Predicate Information (identified by operation id):

---------------------------------------------------

4 - access("EMP"."DEPTNO"="DEPT"."DEPTNO")

filter("EMP"."DEPTNO"="DEPT"."DEPTNO")

Column Projection Information (identified by operation id):

-----------------------------------------------------------

1 - "DNAME"[VARCHAR2,14], "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10]

2 - "DEPT"."DEPTNO"[NUMBER,22], "DNAME"[VARCHAR2,14]

3 - "DEPT".ROWID[ROWID,10], "DEPT"."DEPTNO"[NUMBER,22]

4 - (#keys=1) "EMP"."DEPTNO"[NUMBER,22], "EMPNO"[NUMBER,22],

"ENAME"[VARCHAR2,10]

5 - "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10], "EMP"."DEPTNO"[NUMBER,22]

58 rows selected.

SQL> select * from table(dbms_xplan.display_cursor(null,null,'all'));

PLAN_TABLE_OUTPUT

-------------------------------------------------------------------------------------------

SQL_ID7ww0fhpbqqt0n, child number 0

-------------------------------------

select empno,ename,dname from emp,dept where emp.deptno=dept.deptno

Plan hash value: 844388907

----------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | | | 6 (100)| |

| 1 | MERGE JOIN | | 14 | 364 | 6(17)| 00:00:01 |

| 2 | TABLE ACCESS BY INDEX ROWID| DEPT | 4 | 52 | 2 (0)| 00:00:01 |

| 3 | INDEX FULL SCAN | PK_DEPT | 4 | | 1 (0)| 00:00:01 |

|* 4 | SORT JOIN | | 14 | 182 | 4(25)| 00:00:01 |

| 5 | TABLE ACCESS FULL | EMP | 14 | 182 | 3 (0)| 00:00:01 |

----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):

-------------------------------------------------------------

1 - SEL$1

2 - SEL$1 / DEPT@SEL$1

3 - SEL$1 / DEPT@SEL$1

5 - SEL$1 / EMP@SEL$1

Predicate Information (identified by operation id):

---------------------------------------------------

4 - access("EMP"."DEPTNO"="DEPT"."DEPTNO")

filter("EMP"."DEPTNO"="DEPT"."DEPTNO")

Column Projection Information (identified by operation id):

-----------------------------------------------------------

1 - "DNAME"[VARCHAR2,14], "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10]

2 - "DEPT"."DEPTNO"[NUMBER,22], "DNAME"[VARCHAR2,14]

3 - "DEPT".ROWID[ROWID,10], "DEPT"."DEPTNO"[NUMBER,22]

4 - (#keys=1) "EMP"."DEPTNO"[NUMBER,22], "EMPNO"[NUMBER,22],

"ENAME"[VARCHAR2,10]

5 - "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10], "EMP"."DEPTNO"[NUMBER,22]

41 rows selected.

当参数传入all，显示结果中了“Qutline Data”部分的内容：

方法3是执行 select * from table(dbms_xplan.display_cursor('sql_id/hash_value',child_cursor_number,'advanced'));它用于查看指定sql的执行计划。这里针对方法dbms_xplan.display_cursor所传人的第一个参数的值是指定sql的sql_id或者sql hash value,第二参数的值是要看执行计划所在的child cursor number，第三个参数是advcanced或者all

SQL> select sql_text,sql_id,hash_value,child_number from v$sql where sql_text like 'select empno,ename,dname%';

SQL_TEXT

select empno,ename,dname from emp,dept where emp.deptno=dept.deptno

SQL_ID HASH_VALUE CHILD_NUMBER

------------- ---------- ------------

7ww0fhpbqqt0n 1466655764 0

只要目标sql的执行计划所在的child cursor还没有被page out出shared pool，就可以使用方法3查看该sql的执行计划：

SQL> select * from table(dbms_xplan.display_cursor('2qm0f3qgsqqyc',0,'advanced'));

PLAN_TABLE_OUTPUT

-------------------------------------------------------------------------------------------

SQL_ID2qm0f3qgsqqyc, child number 0

-------------------------------------

select empno,ename,dname from scott.emp,scott.dept where

scott.emp.deptno=scott.dept.deptno

Plan hash value: 844388907

----------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | | | 6 (100)| |

| 1 | MERGE JOIN | | 14 | 364 | 6(17)| 00:00:01 |

| 2 | TABLE ACCESS BY INDEX ROWID| DEPT | 4 | 52 | 2 (0)| 00:00:01 |

| 3 | INDEX FULL SCAN | PK_DEPT | 4 | | 1 (0)| 00:00:01 |

|* 4 | SORT JOIN | | 14 | 182 | 4(25)| 00:00:01 |

| 5 | TABLE ACCESS FULL | EMP | 14 | 182 | 3 (0)| 00:00:01 |

----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):

-------------------------------------------------------------

1 - SEL$1

2 - SEL$1 / DEPT@SEL$1

3 - SEL$1 / DEPT@SEL$1

5 - SEL$1 / EMP@SEL$1

Outline Data

-------------

/*+

BEGIN_OUTLINE_DATA

IGNORE_OPTIM_EMBEDDED_HINTS

OPTIMIZER_FEATURES_ENABLE('11.2.0.4')

DB_VERSION('11.2.0.4')

ALL_ROWS

OUTLINE_LEAF(@"SEL$1")

INDEX(@"SEL$1" "DEPT"@"SEL$1" ("DEPT"."DEPTNO"))

FULL(@"SEL$1" "EMP"@"SEL$1")

LEADING(@"SEL$1" "DEPT"@"SEL$1" "EMP"@"SEL$1")

USE_MERGE(@"SEL$1" "EMP"@"SEL$1")

END_OUTLINE_DATA

Predicate Information (identified by operation id):

---------------------------------------------------

4 - access("EMP"."DEPTNO"="DEPT"."DEPTNO")

filter("EMP"."DEPTNO"="DEPT"."DEPTNO")

Column Projection Information (identified by operation id):

-----------------------------------------------------------

1 - "DNAME"[VARCHAR2,14], "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10]

2 - "DEPT"."DEPTNO"[NUMBER,22], "DNAME"[VARCHAR2,14]

3 - "DEPT".ROWID[ROWID,10], "DEPT"."DEPTNO"[NUMBER,22]

4 - (#keys=1) "EMP"."DEPTNO"[NUMBER,22], "EMPNO"[NUMBER,22],

"ENAME"[VARCHAR2,10]

5 - "EMPNO"[NUMBER,22], "ENAME"[VARCHAR2,10], "EMP"."DEPTNO"[NUMBER,22]

59 rows selected.

我们可以通过dbms_xplan.display_awr来得到该sql的所有历史执行计划：

SQL> set lines 100

SQL> select * from table(dbms_xplan.display_awr('cy097a90nu4fk'));

PLAN_TABLE_OUTPUT

SQL_ID cy097a90nu4fk

--------------------

Plan hash value: 1999179007

-------------------------------------------------------------------------------------------

Inst |IN-OUT|

-------------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | | | 11 (100)| |

| |

| 1 | HASH GROUP BY | | 1 | 101 | 11 (19)| 00:00:01 |

| |

| 2 | VIEW | | 1 | 101 | 10 (10)| 00:00:01 |

| |

| 3 | HASH GROUP BY | | 1 | 261 | 10 (10)| 00:00:01 |

| |

| 4 | FILTER | | | | | |

| |

| 5 | NESTED LOOPS | | | | | |

| |

| 6 | NESTED LOOPS | | 1 | 261 | 9 (0)| 00:00:01 |

| |

| 7 | REMOTE | | 1 | 176 | 5 (0)| 00:00:01 |

DBLK_~ | R->S |

| 8 | INDEX RANGE SCAN | PRODUCTSPEC_PK | 1 | | 1 (0)| 00:00:01 |

| |

| 9 | TABLE ACCESS BY INDEX ROWID| PRODUCTSPEC | 1 | 41 | 2 (0)| 00:00:01 |

| |

-------------------------------------------------------------------------------------------

Remote SQL Information (identified by operation id):

----------------------------------------------------

7 - SELECT "A1"."EVENTTIMEKEY","A1"."EVENTID","A1"."EVENTTIME","A1"."FOLLOTID","A1"."PRODUCTSPECI

D","A1"

."PROCESSFLOWID","A1"."OLDOPERATIONID","A1"."QUANTITY","A1"."EQUIPMENTID","A2"."PROCESSFLOWID

","A2"."REWORK

TYPE" FROM "LOTHISTORY" "A1","PROCESSFLOW" "A2" WHERE "A2"."REWORKTYPE"='Normal' AND

"A1"."PROCESSFLOWID"="A2"."PROCESSFLOWID" AND "A1"."EVENTID"='TrackIn' AND "A1"."OLDOPERATION

ID"='BFOP001'

AND (SUBSTR("A1"."FOLLOTID",1,1)='V' OR SUBSTR("A1"."FOLLOTID",1,1)='P') AND

"A1"."EVENTTIME">=TO_DATE('20140918080001','YYYY-MM-DD HH24:MI:SS') AND

"A1"."EVENTTIME"<=TO_DATE('20140919080000','YYYY-MM-DD HH24:MI:SS') (accessing 'DBLK_RPT_EOL_

PRD' )

55 rows selected.

不过此方法显示执行计划中看不到执行步骤对应的谓词条件。

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