Restoring a ControlFile requires a RECOVER .. FROM BACKUP CONTROLFILE
and, consequently, an INCOMPLETE RECOVERY.

You would do so only when
a. You do not have the current controlfile
b. You are cloning from a hot backup to another server (therefore,
do not have the "current" controlfile and online redologs)
c. You deliberately choose to do an Incomplete Recovery (eg a
Tablespace-Point-In-Time-Recovery
or a simulated Rollback of a Database)

If you lose a Datafile and have the current controlfile , you do not
need to Restore the ControlFile.
Now, that "a Datafile" can mean 1 datafile or multiple datafiles or
all the datafiles in a tablespace.
In all of these cases you do not need to restore the controlfile.
Note : Even if the datafile(s) lost is/are from the SYSTEM
tablespace, you can *still* do a Recovery
without Restoring the controlfile -- except that the database cannot
be OPEN, it can only be MOUNTed.

Hemant
At 02:32 PM Friday, Nadeem M. Khan wrote:
>Greetings.
>
>Got a teeny weeny doubt here.
>When is it necessary to restore the controlfile? Ofcourse one scenario
>is when I have lost all copies of my current control file.
>


Hemant K Chitale
http://hemantoracledba.blogspot.com



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