Oracle HowTo:如何獲得資料庫的DBID

轉載--http://www.eygle.com/archives/2006/02/oracle_howto_get_oracle_dbid.html
在進行資料庫恢複的過程中,很多時候我們需要知道Oracle資料庫的DBID,通常有以下幾種方法可以獲得資料庫的DBID.

1.查詢v$database獲得

由於DBID在控制檔案和資料檔案中都存在記錄,所以如果能夠mount資料庫就可以查詢v$database視圖獲得. 

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

2.在nomount狀態時

如果資料庫配置了自動控制檔案備份(Oracle9i),並且名稱是預設的,那麼我們可以從自動備份檔案獲得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

這裡的3152029224就是DBID.

3.從自動備份中恢複

需要或缺DBID進行恢複通常是因為丟失了所有的控制檔案.在恢複時會遇到錯誤.

[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

如果存在自動備份,我們通常可以直接恢複控制檔案,mount資料庫之後就好辦了: 

RMAN> restore controlfile from '/opt/oracle/product/9.2.0/dbs/c-3152029224-20051221-00'; 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.直接從倖存的檔案中讀取

由於DBID存在於資料檔案及控制檔案中,所以我們可以通過PL/SQL程式直接從檔案中讀取: 

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

這種方法僅為測試興趣所致,不被推薦.