[转帖]清除掉shared pool中某条sql语句方法

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在论坛中看到一个帖子，如何清除掉shared pool中某条sql语句，如果是在10g以前的版本，那估计会比较麻烦，为了删除一条sql语句记录，需要清空整个shared pool，在10g中提供了新的dbms_shared_pool包可以实现该功能(如果该包没有安装，可以通过?/rdbms/admin/dbmspool.sql安装)，下面我通过在11g中试验证明该问题

1.数据库版本信息

SQL> select * from v$version;

 

BANNER

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

 

Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production

PL/SQL Release 11.2.0.1.0 - Production

CORE    11.2.0.1.0      Production

TNS for 32-bit Windows: Version 11.2.0.1.0 - Production

NLSRTL Version 11.2.0.1.0 - Production

2.模拟一条sql语句

SQL> create table xff as

  2  select * from dba_tables

  3  where rownum<10;

 

表已创建。

 

SQL> select count(*) from xff;

 

  COUNT(*)

----------

         9

 

SQL> col sql_text for a30

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

 

ADDRESS  HASH_VALUE SQL_TEXT

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

1EFB91B8 3642190903 select count(*) from xff

3.打破神话一:权限操作
对表进行权限操作，可以清除该表在shared pool中关于该表记录

SQL> grant select on xff to chf;

 

授权成功。

 

SQL> col sql_text for a30

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

 

ADDRESS  HASH_VALUE SQL_TEXT

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

1EFB91B8 3642190903 select count(*) from xff

 

 

SQL> revoke select on xff from chf;

 

撤销成功。

 

SQL> col sql_text for a30

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

ADDRESS  HASH_VALUE SQL_TEXT

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

1EFB91B8 3642190903 select count(*) from xff

证明grant和revoke操作没有清除shared pool中关于该表的sql语句

4.打破神话二:ddl操作
对表进行ddl操作，可以清除该表在shared pool中关于该表记录

SQL> alter table xff add  owner1 varchar2(100);

 

表已更改。

 

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

ADDRESS  HASH_VALUE SQL_TEXT

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

1EFB91B8 3642190903 select count(*) from xff

事实证明ddl操作不能达到预期效果，没有清除掉这条sql语句

5.刷新shared pool

SQL> alter system flush shared_pool

  2  ;

 

系统已更改。

 

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

未选定行

把整个shared pool都刷新了，自然其中的一条sql语句也没有了，在10g前只能通过这种方法实现

6.使用dbms_shared_pool.purge

SQL> select count(*) from xff;

 

  COUNT(*)

----------

         9

 

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

ADDRESS  HASH_VALUE SQL_TEXT

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

1EFB91B8 3642190903 select count(*) from xff

 

SQL> exec dbms_shared_pool.purge('1EFB91B8, 3642190903','C');

 

PL/SQL 过程已成功完成。

 

SQL> SELECT ADDRESS,HASH_VALUE,SQL_TEXT FROM V$SQLAREA

  2  WHERE SQL_TEXT LIKE 'select % xff';

 

未选定行

试验证明在shared pool中清除了一条sql记录

7.关于dbms_shared_pool.purge参数说明

purge(name varchar2, flag char DEFAULT 'P', heaps number DEFAULT 1);

--    name

--      The name of the object to keep.  There are two kinds of objects:

--      PL/SQL objects, triggers, sequences, types and Java objects,

--      which are specified by name, and

--      SQL cursor objects which are specified by a two-part number

--      (indicating a location in the shared pool).  For example:

--        dbms_shared_pool.keep('scott.hispackage')

--      will keep package HISPACKAGE, owned by SCOTT.  The names for

--      PL/SQL objects follows SQL rules for naming objects (i.e.,

--      delimited identifiers, multi-byte names, etc. are allowed).

--      A cursor can be keeped by

--        dbms_shared_pool.keep('0034CDFF, 20348871', 'C')

--      The complete hexadecimal address must be in the first 8 characters.

--      The value for this identifier is the concatenation of the

--      'address' and 'hash_value' columns from the v$sqlarea view.  This

--      is displayed by the 'sizes' call above.

--      Currently 'TABLE' and 'VIEW' objects may not be keeped.

--

--    flag

--      This is an optional parameter.  If the parameter is not specified,

--        the package assumes that the first parameter is the name of a

--        package/procedure/function and will resolve the name.  Otherwise,

--        the parameter is a character string indicating what kind of object

--        to keep the name identifies.  The string is case insensitive.

--        The possible values and the kinds of objects they indicate are

--        given in the following table:

--          Value        Kind of Object to keep

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

--        P          package/procedure/function

--        Q          sequence

--        R          trigger

--        T          type

--            JS         java source

--            JC         java class

--        JR         java resource

--        JD         java shared data

--        C          cursor

--      If and only if the first argument is a cursor address and hash-value,

--        the flag parameter should be set to 'C' (or 'c').

--

--    heaps

--      heaps to purge. e.g if heap 0 and heap 6 are to be purged.

--      1<<0 | 1<<6 => hex 0x41 => decimal 65. so specify heaps=>65.

--      Default is 1 i.e heap 0 which means the whole object will be purged.

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