Oracle HowTo:如何更改数据库的SCN?

很多时候,我们需要调整数据库系统的SCN值,有的是为了恢复的需要,如为了解决ORA-600 2662错误.

而以下修改纯属无聊:

1.通过oradebug修改SCN

[oracle@jumper oracle]$ sqlplus "/ as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Wed Dec 21 10:33:35 2005
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> col a for 999999999999999
SQL> select CHECKPOINT_CHANGE# a from v$datafile;

              A
---------------
   107374358304
   107374358304
   107374358304

SQL> oradebug setmypid
Statement processed.
SQL> oradebug DUMPvar SGA kcsgscn_
kcslf kcsgscn_ [5000BC68, 5000BC88) = 00000019 0002F97F 00004979 
00000000 00000000 00000000 00000000 5000B948
SQL> oradebug poke 0x5000BC69 4 8
BEFORE: [5000BC68, 5000BC70) = 00000019
AFTER:  [5000BC68, 5000BC70) = 00000819

2.确认更改

SQL> select dbms_flashback.get_system_change_number a from dual;

               A
----------------
   8903467399681

SQL> oradebug DUMPvar SGA kcsgscn_
kcslf kcsgscn_ [5000BC68, 5000BC88) = 00000819 0002FA0C 00004A75 
00000000 00000000 00000000 00000000 5000B948
SQL> 
SQL> alter system checkpoint;

System altered.

SQL> select CHECKPOINT_CHANGE# a from v$datafile;

               A
----------------
   8903467399867
   8903467399867
   8903467399867

3.此时无法正常关闭数据库

Oracle会检测到异常:

SQL> shutdown immediate;
ORA-00600: internal error code, arguments: [kfhsls_02], [20], [1], [], [], [], [], []