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在9i中因为某个执行计划因为Oracle Peeking绑定变量的控制导致现有的执行计划不正确,需要清除掉这条sql语句的执行计划.在10g中提供了dbms_shared_pool.purge(见:清除掉shared pool中某条sql语句方法),但是在9i中未提供好的方法,一般来说可以通过对相关表的DDL操作,收集统计信息,授权操作可以实现清除对于表执行计划.注:这些操作不会只清空特定SQL执行计划,而是会清除该表相关的所有执行计划,所以操作需要慎重(影响肯定比flush shared_pool小)
模拟测试数据
SQL> create table t_xifenfei (id number,name varchar2(100)); Table created. SQL> insert into t_xifenfei values(1,'www.xifenfei.com'); 1 row created. SQL> commit;
清除执行计划1:修改表结构
SQL> alter system flush shared_pool;
System altered.
SQL> select * from t_xifenfei;
ID NAME
---------- -------------------
1 www.xifenfei.com
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
OPERATION
------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS
SQL> alter table t_xifenfei add fei varchar2(10);
Table altered.
SQL> alter table t_xifenfei drop COLUMN fei;
Table altered.
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select count(*) from v$sql_plan where hash_value=1067507827;
COUNT(*)
----------
0
清除执行计划2:重新收集统计信息
--DBMS_STATS收集统计信息
SQL> alter system flush shared_pool;
System altered.
SQL> select * from t_xifenfei;
ID NAME
---------- -------------------
1 www.xifenfei.com
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
OPERATION
------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS
SQL> EXEC DBMS_STATS.gather_table_stats(user,'T_XIFENFEI');
PL/SQL procedure successfully completed.
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
no rows selected
--analyze收集统计信息(不推荐)
SQL> alter system flush shared_pool;
System altered.
SQL> select * from t_xifenfei;
ID NAME
---------- -------------------
1 www.xifenfei.com
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
OPERATION
------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS
SQL> analyze table t_xifenfei compute statistics;
Table analyzed.
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
no rows selected
清除执行计划3:创建INDEX
SQL> alter system flush shared_pool;
System altered.
SQL> select * from t_xifenfei;
ID NAME
---------- -------------------
1 www.xifenfei.com
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
OPERATION
------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS
SQL> create index i_txifenfei on t_xifenfei(id) online;
Index created.
SQL> drop index i_txifenfei ;
Index dropped.
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
no rows selected
清除执行计划3:GRANT/REVOKE操作
SQL> alter system flush shared_pool;
System altered.
SQL> select * from t_xifenfei;
ID NAME
---------- -------------------
1 www.xifenfei.com
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
OPERATION
------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS
SQL> GRANT SELECT ON T_XIFENFEI TO SYSTEM;
Grant succeeded.
SQL> select sql_text,HASH_VALUE from v$sqlAREA where sql_text like '%xifenfei';
SQL_TEXT HASH_VALUE
-------------------------------------------------- ----------
select * from t_xifenfei 1067507827
SQL> select OPERATION from v$sql_plan where hash_value=1067507827;
no rows selected