查看执行计划的几种方法?

我的答案

http://blog.csdn.net/zhoubo200/article/details/5345019 

 

1 set autorace trace explain

2 explain plan for sql statements

   select * from table(dbms_xplan.display);

3,跟踪sql的方法  alter session set sql_trace = true;

                         sql statements

                        alter session set sql_trace = off;

根据脚本查找出当前会话的spid,去 $oracle_base/admin/sid/udump/ 下去查找

  跟踪其他会话 dbms_system.set_sql_trace_in_session(sid,serial#,true/false)来跟踪

4 通过用 10046调试事件来实现

  level 0

  level 1

  level 4 bind

  level 8 wait events

  level 12 1+4+8

 alter session set events '10046 trace name context forever,level 8

 sql statement

 alter session set events '10046 trace name context off';

 跟踪其他会话：

sys:

exec dbms_system.set_ev(127,31923,10046,8,'A');

dbms_system.set_ev(sid,serial#,10046,8,'username');

sql statements

dbms_system.set_ev(sid,serial#,10046,0,'username');

5 :oralce 10g引入 dbms_monitors来基于客户标示符，服务名，实例，模块名 来跟踪sql

 

 

 

 

 

1、直接使用sqlplus系统参数： 
 
    SQL> set autotrace on explain 
    SQL> select * from dual; 
    D
    -
    X 
    Execution Plan
    ----------------------------------------------------------
    Plan hash value: 272002086 
    --------------------------------------------------------------------------
    | Id  | Operation                         | Name  | Rows  | Bytes | Cost (%CPU)| Time     |
    --------------------------------------------------------------------------
    |   0 | SELECT STATEMENT  |              |     1     |     2      |     2   (0)         | 00:00:01 |
    |   1 |  TABLE ACCESS FULL | DUAL |     1     |     2      |     2   (0)          | 00:00:01 |
    -------------------------------------------------------------------------- 
    SQL> set autotrace off 
 
    但是这样操作的结果是先执行SQL，再出执行计划，如果SQL耗时巨大，则不现实； 
 
 
2、使用explain plan for语句： 
 
    SQL> explain plan for select * from dual; 
    Explained. 
    SQL> select * from table(DBMS_XPLAN.display); 
    Execution Plan
    ----------------------------------------------------------
    Plan hash value: 2137789089 
    ---------------------------------------------------------------------------------------------
    | Id  | Operation                                                              | Name        | Rows  | Bytes | Cost (%CPU)| Time     |
    ---------------------------------------------------------------------------------------------
    |   0 | SELECT STATEMENT                                       |                   |  8168   | 16336 |    21   (0)| 00:00:01 |
    |   1 |  COLLECTION ITERATOR PICKLER FETCH| DISPLAY |             |       |
    |     |
    --------------------------------------------------------------------------------------------- 
 
    这样就可以在执行SQL之前查看执行计划了 
 
 
3、启用SQL_TRACE跟踪所有后台进程活动： 
 
    全局参数设置： 
    ..OracleHome/admin/SID/pfile中指定: SQL_TRACE = true (10g) 
 
    当前session中设置： 
    SQL> alter session set SQL_TRACE=true; 
    SQL> select * from dual; 
    SQL> alter session set SQL_TRACE=false; 
 
    对其他用户进行跟踪设置： 
    SQL> select sid,serial#,username from v$session where username='XXX'; 
       SID    SERIAL# USERNAME
    ------ ---------- ------------------
       127      31923 A
       128      54521 B 
       129      48940 B 
    SQL> exec dbms_system.set_SQL_TRACE_in_session(127,31923,true); 
    SQL> select * from dual; 
    SQL> exec dbms_system.set_SQL_TRACE_in_session(127,31923,false); 
 
    然后使用oracle自带的tkprof命令行工具格式化跟踪文件。 
 
 
4、使用10046事件进行查询： 
 
    10046事件级别： 
    Lv1  - 启用标准的SQL_TRACE功能,等价于SQL_TRACE 
    Lv4  - Level 1 + 绑定值(bind values) 
    Lv8  - Level 1 + 等待事件跟踪 
    Lv12 - Level 1 + Level 4 + Level 8 
 
    全局设定： 
    ..OracleHome/admin/SID/pfile中指定: EVENT="10046 trace name context forever,level 12" 
 
    当前session设定： 
    SQL> alter session set events '10046 trace name context forever, level 8'; 
    SQL> select * from dual; 
    SQL> alter session set events '10046 trace name context off'; 
 
    对其他用户进行设置： 
    SQL> select sid,serial#,username from v$session where username='XXX'; 
       SID    SERIAL# USERNAME
    ------ ---------- ------------------
       127      31923 A
       128      54521 B 
       129      48940 B     
    SQL> exec dbms_system.set_ev(127,31923,10046,8,'A'); 
    SQL> select * from dual; 
    SQL> exec dbms_system.set_ev(127,31923,10046,0,'A'); 
 
 
 
5、使用tkprof格式化跟踪文件： 
 
    使用一下SQL找到当前session的跟踪文件： 
 

    ---- 当前 session

    SELECT d.value|| '/' ||lower(rtrim(i.instance, chr( 0 )))|| '_ora_' ||p.spid|| '.trc' trace_file_name

    from

    ( select p.spid from v$mystat m,v$session s, v$process p

          where m.statistic# = 1 and s.sid = m.sid and p.addr = s.paddr) p,

    ( select t.instance from v$thread t,v$parameter v

          where v.name = 'thread' and (v.value = 0 or t.thread# = to_number(v.value))) i,

    ( select value from v$parameter where name = 'user_dump_dest' ) d;

      

    ---- 其他用户 session

    SELECT d.value|| '/' ||lower(rtrim(i.instance, chr( 0 )))|| '_ora_' ||p.spid|| '.trc' trace_file_name

    from

    ( select p.spid from v$session s, v$process p

          where s.sid= '127' and s. SERIAL#= '31923' and p.addr = s.paddr) p,

    ( select t.instance from v$thread t,v$parameter v

          where v.name = 'thread' and (v.value = 0 or t.thread# = to_number(v.value))) i,

    ( select value from v$parameter where name = 'user_dump_dest' ) d; 
 
    查找后使用tkprof命令： 
    SQL> $tkprof D:/....../SID_ora_5352.trc D:/....../SID_ora_5352.txt 
 
 

 

注：无法使用autotrace的解决办法（9i）：

SQL>start $ORACLE_HOME/rdbms/admin/utlxplan.sql;

SQL>create public synonym plan_table for plan_table;

SQL>grant ALL on plan_table to public;

-The End-