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Oracle HowTo:如何更改数据库的SCN?

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本文介绍了更改数据库的SCN的问题。

作者：盖国强来源：eygle.com 2007年10月2日

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], [], [], [], [], []

4.shutdown abort强制关闭数据库

重新启动会出现错误

SQL> shutdown abort;
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  114365800 bytes
Fixed Size                   451944 bytes
Variable Size              50331648 bytes
Database Buffers           62914560 bytes
Redo Buffers                 667648 bytes
Database mounted.
ORA-00600: internal error code, arguments: [3756], [1], [25], [195904], [2073], [195259], [], []

5.通过不完全恢复启动数据库

SQL> recover database using backup controlfile until cancel;
ORA-00279: change 8903467399867 generated at 12/21/2005 10:57:34 needed for thread 1
ORA-00289: suggestion : /opt/oracle/oradata/conner/archive/1_18.dbf
ORA-00280: change 8903467399867 for thread 1 is in sequence #18


Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
cancel
ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01194: file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/opt/oracle/oradata/conner/system01.dbf'