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-
