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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