查看执行计划的常用方法

1.autotrace

set autotrace off

不产生autotrace报告，默认值

set autotrace on explain

autotrace报告只展示最优的执行方式（optimizer execution path）

SQL> set autotrace on explain;

—插入数据测试是否执行了sql

SQL> insert into scott.emp values('5566','explain','','','','','','');

1 row created.

—已经表明执行了sql

—只展示了执行计划

Execution Plan

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

 

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

| Id | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time  |

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

|   0 | INSERT STATEMENT  |    |     1 |  100 |     1   (0)| ss00:00:01 |

|   1 | LOAD TABLE CONVENTIONAL | EMP |      |      |          |            |

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

 

SQL> select * from scott.emp whereempno=5566;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM    DEPTNO

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

     5566 explain

 

 

Execution Plan

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

Plan hash value: 2949544139

 

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

| Id | Operation             | Name  | Rows  | Bytes | Cost (%CPU)|Time     |

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

|   0 | SELECT STATEMENT     |           |        1|      87 |        2  (0)| 00:00:01 |

|   1 | TABLE ACCESS BY INDEX ROWID| EMP   |     1 |       87 |        2  (0)| 00:00:01 |

|*  2 |  INDEX UNIQUE SCAN        | PK_EMP |      1 |          |        1  (0)| 00:00:01 |

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

 

Predicate Information (identified byoperation id):

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

 

   2- access("EMPNO"=5566)

 

set autotrace on statistics

autotrace报告sql执行统计信息（SQL statement execution statistics. ）

SQL> set autotrace on statistics;

SQL> insert into scott.empvalues('6677','statistics','','','','','','');

1 row created.

—说明执行了sql

—只展示sql执行的统计信息

Statistics

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

        52 recursive calls

         5  dbblock gets

        80 consistent gets

         0 physical reads

       520  redo size

       839  bytes sent via SQL*Net to client

       826  bytes received via SQL*Net from client

         3 SQL*Net roundtrips to/from client

        10 sorts (memory)

         0 sorts (disk)

         1  rows processed

 

SQL> select * from scott.emp whereempno=6677;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM    DEPTNO

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

     6677 statistics

 

 

Statistics

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

         1 recursive calls

         0  dbblock gets

         2  consistent gets

         0 physical reads

         0  redosize

       869  bytes sent via SQL*Net to client

       512  bytes received via SQL*Net from client

         1 SQL*Net roundtrips to/from client

         0 sorts (memory)

         0 sorts (disk)

         1  rows processed 

 

set autotrace on

autotrace报告包含了最优执行方式和sql执行的信息

SQL> set autotraceon;

SQL> insert into scott.emp  values('8899','on','','','','','','');

 

1 row created.

 

—相当于set autotrace on explain和set autotrace on statistics的和，既输出执行计划，也输出统计信息，同时也执行sql

Execution Plan

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

 

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

| Id | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time  |

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

|   0 | INSERT STATEMENT  |    |     1 |  100 |     1   (0)| 00:00:01 |

|   1 | LOAD TABLE CONVENTIONAL | EMP |      |      |          |            |

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

 

 

Statistics

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

        45 recursive calls

         5  dbblock gets

        77 consistent gets

         0 physical reads

       512  redo size

       839  bytes sent via SQL*Net to client

       816  bytes received via SQL*Net from client

         3 SQL*Net roundtrips to/from client

        10 sorts (memory)

         0 sorts (disk)

         1  rows processed

 

SQL> select * from scott.emp whereempno=8899;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM    DEPTNO

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

     8899 on

 

 

Execution Plan

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

Plan hash value: 2949544139

 

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

| Id | Operation             | Name  | Rows  | Bytes | Cost (%CPU)|Time     |

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

|   0 | SELECT STATEMENT     |           |        1|      87 |        2  (0)| 00:00:01 |

|   1 | TABLE ACCESS BY INDEX ROWID| EMP   |     1 |       87 |        2  (0)| 00:00:01 |

|*  2 |  INDEX UNIQUE SCAN        | PK_EMP |      1 |          |        1  (0)| 00:00:01 |

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

 

Predicate Information (identified byoperation id):

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

 

   2- access("EMPNO"=8899)

 

 

Statistics

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

         9 recursive calls

         0  db blockgets

        18 consistent gets

         0 physical reads

         0  redosize

       861  bytes sent via SQL*Net to client

       512  bytes received via SQL*Net from client

         1 SQL*Net roundtrips to/from client

         0 sorts (memory)

         0 sorts (disk)

         1  rows processed

 

 

set autotrace traceonly

和set autotrace on类似，但是不输出用户查询的结果

SQL> set autotrace traceonly;

SQL> insert into scott.empvalues('9900','traceonly','','','','','','');

 

1 row created.

 

—与set autotrace on 类似，都会输出执行计划和统计信息

Execution Plan

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

 

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

| Id | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time  |

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

|   0 | INSERT STATEMENT  |    |     1 |  100 |     1   (0)| 00:00:01 |

|   1 | LOAD TABLE CONVENTIONAL | EMP |      |      |          |            |

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

 

 

Statistics

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

       108  recursive calls

         5  dbblock gets

       191  consistent gets

         1 physical reads

       520  redo size

       839  bytes sent via SQL*Net to client

       825  bytes received via SQL*Net from client

         3 SQL*Net roundtrips to/from client

        15 sorts (memory)

         0 sorts (disk)

         1  rows processed

 

SQL> select * from scott.emp whereempno=9900;

—与set autotrace on不同的是，没有输出查询结果

Execution Plan

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

Plan hash value: 2949544139

 

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

| Id | Operation             | Name  | Rows  | Bytes | Cost (%CPU)|Time     |

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

|   0 | SELECT STATEMENT     |           |        1|      87 |        2  (0)| 00:00:01 |

|   1 | TABLE ACCESS BY INDEX ROWID| EMP   |     1 |       87 |        2  (0)| 00:00:01 |

|*  2 |   INDEXUNIQUE SCAN        | PK_EMP |      1 |          |        1  (0)| 00:00:01 |

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

 

Predicate Information (identified byoperation id):

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

 

   2- access("EMPNO"=9900)

 

 

Statistics

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

         9 recursive calls

         0  dbblock gets

        18 consistent gets

         0 physical reads

         0  redosize

       867  bytes sent via SQL*Net to client

       512  bytes received via SQL*Net from client

         1 SQL*Net roundtrips to/from client

         0 sorts (memory)

         0 sorts (disk)

         1  rows processed

 

SQL>

 

 

2.dbms_xplan

概述

dbms_xplan包提供了多样的，预定义的方式去解释执行计划。sql执行计划，执行时间等信息都存储与v$sql_plan,v$sql_plan_statistics_all视图中。此包运行的权限是执行用户，不是包的拥有者sys。

当执行display_awr时，需要DBA_HIST_SQL_PLAN, DBA_HIST_SQLTEXT, andV$DATABASE的查询权限

当执行display_cursor时需要V$SQL_PLAN, V$SESSION and V$SQL_PLAN_STATISTICS_ALL的查询权限

当执行display_sql_plan_baseline时，需要DBA_SQL_PLAN_BASELINES的查询权限

当执行display_sqlset时，需要ALL_SQLSET_STATEMENTS and ALL_SQLSET_PLANS的查询权限

以上的所有权限都在SELECT_CATALOG角色中，所以直接赋权SELECT_CATALOG就可以了。

 

dbms_xplan中有许多功能，我这里着重研究其中几个常用的

SQL> desc dbms_xplan;

…

FUNCTION DISPLAY_AWR RETURNSDBMS_XPLAN_TYPE_TABLE

 Argument Name                     Type                    In/Out Default?

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

 SQL_ID                    VARCHAR2        IN

 PLAN_HASH_VALUE            NUMBER(38)             IN     DEFAULT

 DB_ID                       NUMBER(38)             IN     DEFAULT

 FORMAT                 VARCHAR2        IN    DEFAULT

FUNCTION DISPLAY_CURSOR RETURNS DBMS_XPLAN_TYPE_TABLE

 Argument Name                     Type                    In/Out Default?

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

 SQL_ID                    VARCHAR2        IN    DEFAULT

 CURSOR_CHILD_NO           NUMBER(38)             IN     DEFAULT

 FORMAT                 VARCHAR2        IN    DEFAULT

FUNCTION DISPLAY_PLAN RETURNS CLOB

 Argument Name                     Type                    In/Out Default?

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

 TABLE_NAME                 VARCHAR2        IN    DEFAULT

 STATEMENT_ID                    VARCHAR2        IN    DEFAULT

 FORMAT                 VARCHAR2        IN    DEFAULT

 FILTER_PREDS                    VARCHAR2        IN    DEFAULT

 TYPE                        VARCHAR2        IN    DEFAULT

…

 

 

 

dbms_xplan.display

展示执行计划内容

简单的执行一次display

SQL> explain plan for insert intoscott.emp values(1111,'xplan','','','','','','');

 

Explained.

 

SQL> select * from table(dbms_xplan.display);

 

7 rows selected.

 

 

Execution Plan

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

Plan hash value: 2137789089

 

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

| Id | Operation                  | Name   | Rows  | Bytes | Cost (%CPU)|Time     |

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

|   0 | SELECT STATEMENT          |      |  8168 | 16336 | 29  (0)| 00:00:01 |

|   1 | COLLECTION ITERATOR PICKLER FETCH| DISPLAY |  8168 | 16336 | 29   (0)| 00:00:01 |

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

 

 

Statistics

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

      1890  recursive calls

        40  dbblock gets

       3635 consistent gets

         0 physical reads

         0  redosize

      1102  bytes sent via SQL*Net toclient

       523  bytes received via SQL*Net from client

         2  SQL*Net roundtrips to/from client

        38 sorts (memory)

         0 sorts (disk)

         7  rowsprocessed

SQL> select * from scott.emp whereempno=1111;

 

no rows selected

—explain plan for ，dbms_xplan.display都没有执行sql。explain plan for是产生sql的执行计划并保存在PLAN_TABLE表中，dbms_xplan.display从PLAN_TABLE中提取计划并展示出来。

 

定义

DBMS_XPLAN.DISPLAY(

   table_name   IN  VARCHAR2  DEFAULT 'PLAN_TABLE',

   statement_id IN  VARCHAR2  DEFAULT NULL,

  format            IN  VARCHAR2  DEFAULT 'TYPICAL',

  filter_preds     IN  VARCHAR2 DEFAULT NULL);

 

table_name：指定的是计划的存储表表名（不是执行表的表名）。默认是PLAN_TABLE。

statement_id：指定计划的statement_id，如果没有指定，则该值为explain plan的statement_id , 如果没有expain plan，则该值为最近一次解释的执行计划。

format：解释计划的level

       •      BASIC: Displays the minimum information inthe plan—the operation ID, the operation name and its option.展示最少的信息

       •      TYPICAL: This is the default. Displays themost relevant information in the plan (operation id, name and option, #rows,#bytes and optimizer cost). Pruning, parallel and predicate information areonly displayed when applicable. Excludes only PROJECTION, ALIAS and REMOTE SQLinformation (see below).默认值

       •      SERIAL: Like TYPICAL except that theparallel information is not displayed, even if the plan executes in parallel.没有并发信息

  •  ALL: Maximum user level. Includesinformation displayed with the TYPICAL level with additional information(PROJECTION, ALIAS and information about REMOTE SQL if the operation isdistributed).展示最多的信息，包含了分布式操作的远程sql执行信息

filter_preds：sql过滤，限制从计划表中返回的行。

 

dbms_xplan.display_awr 

展示在awr中存储的sql的执行计划

 

定义

DBMS_XPLAN.DISPLAY_AWR(

  sql_id            IN      VARCHAR2,

   plan_hash_value   IN     NUMBER DEFAULT NULL,

  db_id             IN      NUMBER DEFAULT NULL,

  format            IN      VARCHAR2 DEFAULT TYPICAL);

 

sql_id:在dba_hist_sqltext中可以找到sql_id

plan_hash_value:sql执行计划的hash值。如果该值被忽略，则函数返回sql_id中的所有执行计划

db_id：database_id。如果不知道则该值为V$DATABASE视图中的database_id，也就是本地数据库。

format：与display类似。总共有4个level：BASIC，TYPICAL,SERIAL,ALL。

 

SQL> select * from scott.emp whererownum<=1;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM

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

    DEPTNO

----------

     7369 SMITH      CLERK         7902 17-DEC-80         800

       20

 

—手动生成快照

SQL> EXECUTE DBMS_WORKLOAD_REPOSITORY.CREATE_SNAPSHOT();

 

PL/SQL procedure successfully completed.

 

SQL> select sql_id,sql_text from dba_hist_sqltext where sql_text like '%rownum%';

bd3tcy3ar02px

select * from scott.emp where rownum<=1

 

SQL>

—指定awr中存在sql

SQL> select * fromtable(dbms_xplan.display_awr('bd3tcy3ar02px'));

 

PLAN_TABLE_OUTPUT

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

SQL_ID bd3tcy3ar02px

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

select * from scott.emp where rownum<=1

 

Plan hash value: 1973284518

 

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

| Id | Operation     | Name | Rows  | Bytes | Cost (%CPU)| Time       |

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

|  0 | SELECT STATEMENT   |    |     |     |   2 (100)|   |

|   1 | COUNT STOPKEY       |   |     |     |          |   |

 

PLAN_TABLE_OUTPUT

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

|   2 |  TABLE ACCESS FULL| EMP  |    15 | 1305 |      2   (0)| 00:00:01 |

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

 

Note

-----

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

 

 

18 rows selected.

 

SQL>

 

 

 

 

dbms_xplan.display_cursor

展示cursor中的执行计划

定义

DBMS_XPLAN.DISPLAY_CURSOR(

  sql_id           IN  VARCHAR2 DEFAULT  NULL,

   cursor_child_no  IN NUMBER    DEFAULT  0,

  format           IN  VARCHAR2 DEFAULT  ‘TYPICAL');

 

sql_id

cursor_child_no:子游标标志。如果没有指定，则展示sql_id下的所有执行计划

format 展示方式

 

默认值执行

SQL> select * from scott.emp whererownum<=2;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM

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

    DEPTNO

----------

     7369 SMITH      CLERK         7902 17-DEC-80         800

       20

 

     7499 ALLEN      SALESMAN        7698 20-FEB-81        1600       300

       30

—默认查询了当前session最后一次执行sql

 

SQL> select * fromtable(dbms_xplan.display_cursor);

 

PLAN_TABLE_OUTPUT

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

SQL_ID 90ud69jbjz75c,child number 0

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

select * from scott.emp where rownum<=2

 

Plan hash value: 1973284518

 

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

| Id | Operation     | Name | Rows  | Bytes | Cost (%CPU)| Time       |

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

|  0 | SELECT STATEMENT   |    |     |     |   2 (100)|   |

|*  1 | COUNT STOPKEY        |   |     |     |          |   |

 

PLAN_TABLE_OUTPUT

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

|   2 |  TABLE ACCESS FULL| EMP  |    15 | 1305 |      2   (0)| 00:00:01 |

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

 

Predicate Information (identified byoperation id):

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

 

   1- filter(ROWNUM<=2)

 

Note

-----

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

 

PLAN_TABLE_OUTPUT

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

 

 

23 rows selected.

 

SQL>

 

指定sql_id查找plan，首先要找到sql_id

SQL> select sql_id,sql_text fromv$sqlarea where sql_text like '%rownum<=2%';

 

SQL_ID

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

SQL_TEXT

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

75gpskbx0uk8w

select sql_id,sql_text from v$sqlarea wheresql_text like '%rownum<=2%'

 

90ud69jbjz75c

select * from scott.emp where rownum<=2

 

 

SQL> select * fromtable(dbms_xplan.display_cursor('90ud69jbjz75c'));

 

PLAN_TABLE_OUTPUT

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

SQL_ID 90ud69jbjz75c,child number 0

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

select * from scott.emp where rownum<=2

 

Plan hash value: 1973284518

 

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

| Id | Operation     | Name | Rows  | Bytes | Cost (%CPU)| Time       |

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

|  0 | SELECT STATEMENT   |    |     |     |   2 (100)|   |

|*  1 | COUNT STOPKEY        |   |     |     |          |   |

 

PLAN_TABLE_OUTPUT

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

|   2 |  TABLE ACCESS FULL| EMP  |    15 | 1305 |      2   (0)| 00:00:01 |

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

 

Predicate Information (identified byoperation id):

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

 

   1- filter(ROWNUM<=2)

 

Note

-----

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

 

PLAN_TABLE_OUTPUT

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

 

 

23 rows selected.

如果sql不在内存中，则不能通过cursor方式查询

SQL> select * fromtable(dbms_xplan.display_cursor('90ud69jbjz75c'));

 

PLAN_TABLE_OUTPUT

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

SQL_ID: 90ud69jbjz75c, child number: 0cannot be found

 

这时就可以通过生成快照的方式从awr中查询plan

 

3.10046事件

概述

这是一个特殊的事件，可以被用来发起sql_trace类的活动

使用10046的优势就是可以在trace文件中看到详细的数据库活动细节，细节信息也取决于事件的level。

level

1：标准的sql_trace

4:level 1加上绑定变量      [ bind=true ]

8:levle 1加上等待。在定位等待事件的时候很有用  [ wait=true ]

12:常用的level，包含了level 1，绑定变量，等待，默认stat line。相当于（4+8）

16:每次执行都生成stat line。11g新增。 [ plan_stat=all_executions ]

32:不生成执行统计。11g新增  。[ plan_stat=never ]

64:Adaptive dump of STAT lines. This dumps the STATinformation if a SQL took more than about 1 minute thereby giving informationfor the more expensive SQLs and for different executions of such  SQLs。11gR2新增。 [ plan_stat=adaptive ]

 

使用10046事件

session级追踪

—查看trace的位置

SQL> show parameter user_dump_dest

 

NAME                              TYPE   VALUE

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

user_dump_dest                    string    /u01/app/oracle/diag/rdbms/zld

                                           b/zldb/trace

—tracefile标志

SQL> alter session settracefile_identifier='liuzhilong';

 

Session altered.

—开启10046

SQL> alter session set events '10046trace name context forever,level 12';

 

Session altered.

 

SQL> select * from scott.emp whererownum<=1;

 

     EMPNO ENAME      JOB          MGR HIREDATE      SAL       COMM

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

    DEPTNO

----------

     7369 SMITH      CLERK         7902 17-DEC-80         800

       20

 

 

SQL>

 

 

退出sqlplus（session级）或者使用以下语句关闭事件

alter session set events '10046 trace namecontext off’;

 

[root@lzl Desktop]# cd/u01/app/oracle/diag/rdbms/zldb/zldb/trace/

[root@lzl trace]# ls *liu*

zldb_ora_2990_liuzhilong.trc  zldb_ora_2990_liuzhilong.trm

 

 

使用oradebug工具

SQL> oradebug setmypid

Statement processed.

SQL> oradebug event 10046 trace name context forever, level 12;

Statement processed.

SQL> select ename from scott.emp whererownum<=1;

 

ENAME

----------

SMITH

 

SQL> oradebug tracefile_name;

/u01/app/oracle/diag/rdbms/zldb/zldb/trace/zldb_ora_2990.trc

SQL>

 

参考文档

AUTOTRACE Option inSQL*Plus (文档 ID 43214.1)

Display Execution Plans withDBMS_XPLAN.DISPLAY (文档 ID 236026.1)

Using DBMS_XPLAN.DISPLAY_CURSOR toIdentify Bind Values Used During Parse (文档 ID 416324.1)

EVENT: 10046 "enable SQL statementtracing (including binds/waits)" (文档 ID 21154.1)

* How To Collect 10046 Trace (SQL_TRACE)Diagnostics for Performance Issues (文档 ID 376442.1)