1.?oracle10g以前我們都是直接刷新共享池，但這樣數據庫中所有sql的執行計劃都會被刪掉。這種辦法也不可取，下面簡單介紹一下這種辦法：

測試版本：

SQL> select * from v$version;

BANNER CON_ID

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

Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production 0

1

2

3

4

SQL>select *fromv$version;

BANNERCON_ID

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

OracleDatabase12cEnterpriseEditionRelease12.1.0.1.0-64bitProduction0

PL/SQL Release 12.1.0.1.0 - Production 0

CORE 12.1.0.1.0 Production 0

TNS for Linux: Version 12.1.0.1.0 - Production 0

NLSRTL Version 12.1.0.1.0 - Production 0

1

2

3

4

PL/SQLRelease12.1.0.1.0-Production0

CORE12.1.0.1.0Production0

TNSforLinux:Version12.1.0.1.0-Production0

NLSRTLVersion12.1.0.1.0-Production0

1.?我們執行一條簡單的sql：

SQL> select 1 from dual;

1

----------

1

1

2

3

4

5

SQL>select1fromdual;

1

----------

1

2.?此時sql的執行計劃進入shared?pool，但共享池中還有其他sql的執行計劃

SQL> select sql_id, address, hash_value, executions, loads, parse_calls, invalidations from v$sqlarea where sql_text = 'select 1 from dual';

SQL_ID ADDRESS HASH_VALUE EXECUTIONS LOADS PARSE_CALLS INVALIDATIONS

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

520mkxqpf15q8 000000006ECCF9C0 2866845384 1 1 1 0

SQL> select count(*) from v$sqlarea;

COUNT(*)

----------

196

1

2

3

4

5

6

7

8

SQL>selectsql_id,address,hash_value,executions,loads,parse_calls,invalidationsfromv$sqlareawheresql_text='select 1 from dual';

SQL_IDADDRESSHASH_VALUEEXECUTIONSLOADSPARSE_CALLSINVALIDATIONS

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

520mkxqpf15q8000000006ECCF9C028668453841110

SQL>selectcount(*)fromv$sqlarea;

COUNT(*)

----------

196

3.?然后flush一下共享池

SQL> alter system flush shared_pool;

System altered.

1

2

3

SQL>altersystemflushshared_pool;

Systemaltered.

4.?發現最開始那條sql的執行計劃已經被flush，但同時共享池所有的sql也被flush，這個代價是非常大的。不可取

SQL> select sql_id, address, hash_value, executions, loads, parse_calls, invalidations from v$sqlarea where sql_text = 'select 1 from dual';

no rows selected

SQL> select count(*) from v$sqlarea;

COUNT(*)

----------

83

1

2

3

4

5

6

7

SQL>selectsql_id,address,hash_value,executions,loads,parse_calls,invalidationsfromv$sqlareawheresql_text='select 1 from dual';

norowsselected

SQL>selectcount(*)fromv$sqlarea;

COUNT(*)

----------

83

2.?下面我們來看一下刪除指定sql的執行計劃，10.2.0.5版本以上可直接使用

1.?執行一條簡單的測試sql

SQL> select 2 from dual;

2

----------

2

1

2

3

4

5

SQL>select2fromdual;

2

----------

2

2.?查看sql在共享池的執行計劃

SQL> select sql_id, address, hash_value, executions, loads, parse_calls, invalidations

2 from v$sqlarea

3 where sql_text = 'select 2 from dual';

SQL_ID ADDRESS HASH_VALUE EXECUTIONS LOADS PARSE_CALLS INVALIDATIONS

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

9fusd37prv595 000000006C5D2988 3950875941 1 1 1 0

1

2

3

4

5

6

7

SQL>selectsql_id,address,hash_value,executions,loads,parse_calls,invalidations

2fromv$sqlarea

3wheresql_text='select 2 from dual';

SQL_IDADDRESSHASH_VALUEEXECUTIONSLOADSPARSE_CALLSINVALIDATIONS

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

9fusd37prv595000000006C5D298839508759411110

3.?將指定sql的執行計劃flush

SQL> exec sys.dbms_shared_pool.purge('000000006C5D2988,3950875941', 'c');

PL/SQL procedure successfully completed.

1

2

3

SQL>execsys.dbms_shared_pool.purge('000000006C5D2988,3950875941','c');

PL/SQLproceduresuccessfullycompleted.

4.然后我們再來查看這條sql的執行計劃的時候，已經被flush掉了

SQL> select sql_id, address, hash_value, executions, loads, parse_calls, invalidations

2 from v$sqlarea

3 where sql_text = 'select 2 from dual';

no rows selected

1

2

3

4

5

SQL>selectsql_id,address,hash_value,executions,loads,parse_calls,invalidations

2fromv$sqlarea

3wheresql_text='select 2 from dual';

norowsselected

刪除完畢。就這樣就刪掉了指定sql的執行計劃了。

轉載請注明: 版權所有，文章允許轉載，但必須以鏈接方式注明源地址，否則追究法律責任!

最后編輯：2013-09-26作者：Jerry

一個積極向上的小青年，熱衷于分享--Focus on DB,BI,ETL

總結

以上是生活随笔為你收集整理的oracle 删除列 大数据_Oracle 删除指定sql的执行计划。的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。