Control file question


Q & A:

>1) Someone confirm/rectify these statements for me (database is in
>archivelog mode): 1) If you loose ALL your control files (I know, very
>unlikely but just for the sake of the argument and to try to understand the
>concept), the only way out is to retrieve a backup control file and perform
>an incomplete recovery.

No, this is not the only way (btw, under the normal circumstances
there is no reason why you couldn't perform a *complete* recovery with
the backup control file). If you know the location of all of your
logfiles and datafilesyou can recreate the lost controlfile by using
command CREATE CONTROLFILE ....

>2) If you have an older control file, you cannot just
>apply archive logs generated after the loss of control files to update the
>status of your database to the status of your log files. The SCN in the
>control file is what determines up to which stage you can restore your
>database. So with an older control file (from a backup for instance), the
>only solution is an incomplete recovery. Answer needed urgently for tests
>that we are currently conducting. In advance, thanks. Miary.

Again, this isn't the true either. With an older controlfile, you can
recover the database to the latest SCN in any of your files. When you
try to recover in such situation, the database itself will force you
to use the proper syntax of the RECOVER command:

RECOVER DATABASE USING BACKUP CONTROLFILE;

And after the recovery is completed, it will force you to open the
database with the RESETLOGS option.

ALTER DATABASE OPEN RESETLOGS;



Ans2:
If you loose your current controlfile, the only option is incomplete
recovery. But while recovering use the 'using backup controlfile' clause and
you will be able to recover to the last archive log. There will not be any
loss of data unless you loose your online redo logs or any of the archive
logs required for recovery.
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