今天一朋友和我说他的数据库不能open,open过程提示ORA-00900错误,通过分析alert日志和props$表,发现他们修改了一个无效的NLS_CHARACTERSET值，导致数据库无法正常启动(准确的说，因为数据库里面该值无效，当数据库open的过程中，检测到控制文件指定的编码和该值不一致，然后修改控制文件的编码，修改之后，数据库一到mount状态执行任何语句都报ORA-00900错误),通过一些工具修改NLS_CHARACTERSET为正确值该故障解决
重现ORA-00900故障
SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> select value$ from props$ where name='NLS_CHARACTERSET'; VALUE$ ------------------------------------------------------- ZHS16GBK SQL> update props$ set value$='AL16UTF16' where name='NLS_CHARACTERSET'; 1 row updated. SQL> commit; Commit complete. SQL> alter database backup controlfile to trace as '/tmp/ora11g.ctl'; Database altered. SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started. Total System Global Area 175775744 bytes Fixed Size 1343668 bytes Variable Size 117444428 bytes Database Buffers 50331648 bytes Redo Buffers 6656000 bytes Database mounted. ORA-01092: ORACLE instance terminated. Disconnection forced ORA-00604: error occurred at recursive SQL level 1 ORA-00900: invalid SQL statement Process ID: 5277 Session ID: 125 Serial number: 5 SQL> startup nomount; ORACLE instance started. Total System Global Area 175775744 bytes Fixed Size 1343668 bytes Variable Size 117444428 bytes Database Buffers 50331648 bytes Redo Buffers 6656000 bytes SQL> alter database mount; Database altered. SQL> alter database open; alter database open * ERROR at line 1: ORA-00900: invalid SQL statement SQL>select * from dual; select * from dual * ERROR at line 1: ORA-00900: invalid SQL statement SQL> shutdown abort ORACLE instance shut down.
第一次startup(open)过程报错
SMON: enabling tx recovery Updating character set in controlfile to AL16UTF16 Errors in file /u01/oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_ora_5277.trc: ORA-00604: error occurred at recursive SQL level %s ORA-00900: invalid SQL statementursive SQL level %s Errors in file /u01/oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_ora_5277.trc: ORA-00604: error occurred at recursive SQL level %s ORA-00900: invalid SQL statementursive SQL level %s Error 604 happened during db open, shutting down database USER (ospid: 5277): terminating the instance due to error 604 Errors in file /u01/oracle/diag/rdbms/ora11g/ora11g/trace/ora11g_smon_5243.trc: ORA-00604: error occurred at recursive SQL level %s ORA-00900: invalid SQL statementursive SQL level %s Instance terminated by USER, pid = 5277 ORA-1092 signalled during: ALTER DATABASE OPEN... opiodr aborting process unknown ospid (5277) as a result of ORA-1092 Sat May 18 00:44:27 2013 ORA-1092 : opitsk aborting process
这里比较明显的看到有一条(Updating character set in controlfile to AL16UTF16),正是由于这个操作，更新控制文件的编码为一个无效的编码，从而导致在后面数据库mount(加载控制文件)之后，就不能再进行其他任何操作
解决思路
使用odu找出来block位置，或者在同版本库中查询
使用dul或者bbed修改props$的NLS_CHARACTERSET值
重建控制文件(noresetlogs方式)
处理过程
SQL> shutdown abort ORACLE instance shut down. odu找出来block位置 dul或者bbed修改block值 重建控制文件(noresetlogs方式) SQL> startup ORACLE instance started. Total System Global Area 175775744 bytes Fixed Size 1343668 bytes Variable Size 117444428 bytes Database Buffers 50331648 bytes Redo Buffers 6656000 bytes Database mounted. ORA-01113: file 1 needs media recovery ORA-01110: data file 1: '/u01/oracle/oradata/ora11g/system01.dbf' SQL> recover database; Media recovery complete. SQL> alter database open; Database altered.
从oracle 9i开始，修改数据库的编码，直接使用alter database character set internal_use方式进行,而不要使用直接修改props$基表,更不能修改一个实际中不存在的编码值(本文中数据库编码和国家编码搞混淆从而出现该故障)
