Oracle 从缓存里面查找真实的执行计划

有关Oracle 的执行计划说明，参考我的Blog：

            Oracle Explain Plan

一.  查看当前session 的SID

SYS@anqing1(rac1)> SELECT USERENV('SID') FROM DUAL;

USERENV('SID')

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

137

SYS@anqing1(rac1)> SELECT SID FROM V$MYSTAT WHERE ROWNUM =1;

SID

----------

 137

二.  查看缓存中的Explain Plan

1）根据SID，从v$sql中找到相应SQL的HASH_VALUE和ADDRESS

/* Formatted on 2011/6/20 17:38:20 (QP5 v5.163.1008.3004) */

SELECT a.sql_text, a.address, a.hash_value

  FROM v$sql a, v$session b

 WHERE a.hash_value = b.sql_hash_value AND b.sid = &sid;

2）根据hash_value和address的值，从v$sql_plan中找到真实的执行计划

/* Formatted on 2011/6/20 17:39:22 (QP5 v5.163.1008.3004) */

   SET LINE 200;

   COL oper FORMAT a100;

    SELECT LPAD (oper, LENGTH (oper) + LEVEL * 2, ' ') oper, cost

      FROM (SELECT object_name || ':' || operation || ' ' || options AS oper,

                   cost,

                   id,

                   parent_id

              FROM v$sql_plan

             WHERE hash_value = '&hash_value' AND address = '&address')

START WITH id = 0

CONNECT BY PRIOR id = parent_id;

如：