Oracle10g中过程(PROCEDURE )重建的增强

作者:eygle |English Version 【转载时请以超链接形式标明文章出处和作者信息及本声明】

链接:http://www.eygle.com/archives/2007/04/oracle10glastddl_time.html

dcba上周有了一个新的发现,在Oracle10g中,当重建一个存储过程时,Oracle的行为和以前有所不同。

在Oracle9i中,即使一个完全相同的过程的重建,Oracle也需要重新编译过程,这个可以从LASTDDLTIME看出:

[oracle@jumper oracle]$ sqlplus eygle/eygle


SQL*Plus: Release 9.2.0.4.0 - Production on Sat Mar 31 17:52:55 2007

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.


Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production

SQL> create or replace PROCEDURE pining
2 IS
3 BEGIN
4 NULL;
5 END;
6 /

Procedure created.

SQL> select object_name,last_ddl_time from dba_objects where object_name='PINING';

OBJECT_NAME LAST_DDL_TIME
------------------------------ -------------------
PINING 2007-03-31 17:52:58

SQL> create or replace PROCEDURE pining
2 IS
3 BEGIN
4 NULL;
5 END;
6 /

Procedure created.

SQL> select object_name,last_ddl_time from dba_objects where object_name='PINING';

OBJECT_NAME LAST_DDL_TIME
------------------------------ -------------------
PINING 2007-03-31 17:54:35

在Oracle10g中,这个LASTDDLTIME不再变化,这说明在10g中,当我们执行create or replace PROCEDURE 时,Oracle现在先尝试进行过程检查,如果内容没有变化,则不需要对过程进行重新编译,这可以减少Cache中的Invalidation,从而可以减少竞争:

$ sqlplus eygle/eygle


SQL*Plus: Release 10.2.0.1.0 - Production on Sat Mar 31 17:44:46 2007

Copyright (c) 1982, 2005, Oracle. All rights reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

SQL> create or replace PROCEDURE pining
2 IS
3 BEGIN
4 NULL;
5 END;
6 /

Procedure created.

SQL> alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

Session altered.

SQL> col object_name for a30
SQL> select object_name,last_ddl_time from dba_objects where object_name='PINING';

OBJECT_NAME LAST_DDL_TIME
------------------------------ -------------------
PINING 2007-03-31 17:45:25

SQL> create or replace PROCEDURE pining
2 IS
3 BEGIN
4 NULL;
5 END;
6 /

Procedure created.

SQL> select object_name,last_ddl_time from dba_objects where object_name='PINING';

OBJECT_NAME LAST_DDL_TIME
------------------------------ -------------------
PINING 2007-03-31 17:45:25

这个我已经在实际过程确认是存在的。