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
----------
1363251591
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-1363251591-20051221-00
-rw-r----- 1 oracle dba 3358720 Jan 21 14:03 c-1363251591-20060121-00
-rw-r----- 1 oracle dba 3358720 Jan 21 14:08 c-1363251591-20060121-01
这里的1363251591就是DBID。在10g中，使用Flash Recovery Area，则没有这个命名规则。
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 - Production
Copyright (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-06
using target database controlfile instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=11 devtype=DISK
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of restore command at 02/05/2006 20:47:25
RMAN-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-1363251591-20051221-00‘;
Starting restore at 05-FEB-06
using channel ORA_DISK_1
channel ORA_DISK_1: restoring controlfile
channel ORA_DISK_1: restore complete
replicating controlfile
input filename=/opt/oracle/oradata/conner/control01.ctl
output filename=/opt/oracle/oradata/conner/control02.ctl
output filename=/opt/oracle/oradata/conner/control03.ctl
Finished 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
------------------------------
1363251591
SQL> select dbid from v$database;
DBID
----------
1363251591
其实更简单的，用BBED就好了。
这种方法仅为测试兴趣所致,不被推荐.
--此处为eygle自定义的函数 （抽时间我会补上）
5、通过dump数据文件获取dbid：
SYS@orcl> alter system dump datafile ‘D:\APP\ADMINISTRATOR\ORADATA\ORCL\USERS01.DBF‘ block 1000;
系统已更改。
SYS@orcl> select tracefile from v$process where addr in (select paddr from v$session where sid in (select sid from v$mystat));
--查看trace文件：Db ID=1363251591
TRACEFILE
------------------------------------------------------------------------------
d:\app\administrator\diag\rdbms\orcl\orcl\trace\orcl_ora_6740.trc
Start dump data block from file D:\APP\ADMINISTRATOR\ORADATA\ORCL\USERS01.DBF minblk 0 maxblk -1
V10 STYLE FILE HEADER:
Compatibility Vsn = 186646528=0xb200000
Db ID=1363251591=0x51419187, Db Name=‘ORCL‘
Activation ID=0=0x0
Control Seq=10579=0x2953, File size=1600=0x640
File Number=4, Blksiz=8192, File Type=3 DATA
Dump all the blocks in range:
...
-------------------------------
Dylan Presents.