在进行数据库恢复的过程中,很多时候我们需要知道Oracle数据库的DBID,通常有以下几种方法可以获得数据库的DBID.

1.查询v$database获得

由于DBID在控制文件和数据文件中都存在记录,所以如果能够mount数据库就可以查询v$database视图获得.

SQL> alter database mount;Database altered.SQL> select dbid from v$database; DBID----------3152029224SQL>

2.在nomount状态时

如果数据库配置了自动控制文件备份(Oracle9i),并且名称是缺省的,那么我们可以从自动备份文件获得DBID.

[oracle@jumper dbs]$ cd $ORACLE_HOME/dbs[oracle@jumper dbs]$ ll c-*-rw-r----- 1 oracle dba 3375104 Dec 21 11:13 c-3152029224-20051221-00-rw-r----- 1 oracle dba 3358720 Jan 21 14:03 c-3152029224-20060121-00-rw-r----- 1 oracle dba 3358720 Jan 21 14:08 c-3152029224-20060121-01

这里的3152029224就是DBID.

3.从自动备份中恢复

需要或缺DBID进行恢复通常是因为丢失了所有的控制文件.在恢复时会遇到错误.

[oracle@jumper dbs]$ rman target /Recovery Manager: Release 9.2.0.4.0 - ProductionCopyright (c) 1995, 2002, Oracle Corporation. All rights reserved.connected to target database: conner (not mounted)RMAN> restore controlfile from autobackup;Starting restore at 05-FEB-06using target database controlfile instead of recovery catalogallocated channel: ORA_DISK_1channel ORA_DISK_1: sid=11 devtype=DISKRMAN-00571: ===========================================================RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============RMAN-00571: ===========================================================RMAN-03002: failure of restore command at 02/05/2006 20:47:25RMAN-06495: must explicitly specify DBID with SET DBID command

如果存在自动备份,我们通常可以直接恢复控制文件,mount数据库之后就好办了:

RMAN> restore controlfile from '/opt/oracle/product/9.2.0/dbs/c-3152029224-20051221-00';Starting restore at 05-FEB-06using channel ORA_DISK_1channel ORA_DISK_1: restoring controlfilechannel ORA_DISK_1: restore completereplicating controlfileinput filename=/opt/oracle/oradata/conner/control01.ctloutput filename=/opt/oracle/oradata/conner/control02.ctloutput filename=/opt/oracle/oradata/conner/control03.ctlFinished restore at 05-FEB-06

4.直接从幸存的文件中读取

由于DBID存在于数据文件及控制文件中,所以我们可以通过PL/SQL程序直接从文件中读取:

SQL> select eygle.get_dbid('/opt/oracle/oradata/conner','user02.dbf') from dual;EYGLE.GET_DBID('/OPT/ORACLE/OR------------------------------3152029224SQL> select dbid from v$database;DBID----------3152029224