Database restore with just one backup set

Question

Hallo experts,
I got a big problem with restoring my XE database. I have a newly created full backup from my XE. While saving the flashback_area I got a hard crash on my system but I saved the last backup set file on a server. Unfortunately I was not able to save other backup sets and I think, there was a special backup of my control files. The restore on another system does not work because of invalid piece.
The data of this database is necessary for my work. Is there anybody out there who can help to restore the data with the existing backup set.
I did not change the entire structure of my original XE database. I only created to schemas with data in. is there any solution to restore the data.
Thanks for any help.
Holger

Answer 1

Hi you all,
I think that somebody will be interested in the solution of my problem,so I post it here and in german on my website (www.datacubus.de).
My XEdatabase is successfully restored and I walked through some undocumented and not supported features of ORACLE to win the challenge.
The first fact is, that ORACLE XE has a very static structure if you use it as is. The datafiles are predefined and so a manual restore with a foreign backup piece seems to be possible.
Here is my way:
Create a backup of your controlfile
ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
Shutdown your database
shutdown immediate
Start the database in nomount mode
[holger@MSA04071]$ rman nocatalog target /
RMAN> startup force nomount;
RMAN> quit
Restore the datafiles
I used the following script to restore the datafiles from the backup piece without any check:
declare
devtype varchar2(256);
v_file varchar2(255);
done boolean;
begin
v_file:='/usr/lib/oracle/xe/app/oracle/flash_recovery_area/XE/backupset/o1_mf_nnndf_TAG20070420T234848_32lfb0w9_.bkp';
devtype:= dbms_backup_restore.DeviceAllocate(type => '',ident => 'D1');
dbms_backup_restore.RestoreSetDatafile;
dbms_backup_restore.RestoreDatafileTo(dfnumber => 1,toname=>'/usr/lib/oracle/xe/oradata/XE/system.dbf');
dbms_backup_restore.RestoreDatafileTo(dfnumber => 2,toname=>'/usr/lib/oracle/xe/oradata/XE/undo.dbf');
dbms_backup_restore.RestoreDatafileTo(dfnumber => 3,toname=>'/usr/lib/oracle/xe/oradata/XE/sysaux.dbf');
dbms_backup_restore.RestoreDatafileTo(dfnumber => 4,toname=>'/usr/lib/oracle/xe/oradata/XE/users.dbf');
dbms_backup_restore.RestoreBackupPiece(done => done,handle => v_file,params => null);
dbms_backup_restore.DeviceDeallocate;
end;
Start this script as sysdba. But by carefull. This only works if no entire change of datafiles had taken place!
Reset DBID
Because of the saved DBID within the datafile, the database can't be opened. But there is a little trick for resetting the DBID.
shutdown;
startup mount;
execute dbms_backup_restore.zeroDbid(0);
shutdown normal;
Delete or rename existing Controlfile
Edit trace file
You have to modify your controlfile script as follows:
1. Only use the CREATE CONTROLFILE... block
2. Delete RECOVER DATABASE block
3. Replace REUSE with SET
4. Replace NORESETLOGS with RESETLOGS
Create new control file
Use the CREATE CONTROLFILE block for creation of a new control file.
Open Database
alter database open resetlogs;
Much work but all my data is back and now I will backup the whole flashback_area to avoid further nightmares.
Bye
Holger