Following an incomplete point-in-time
recovery or recovery without a backup control file, it will be necessary to open the database with the
OPEN RESETLOGS option
as follows:
SQL> alter
database open resetlogs;
The OPEN RESETLOGS operation creates a new
incarnation of the database, resets the log sequence to 1 and online
redo logs are given a new time stamp and SCN. Prior to Oracle
10g, the newly generated redo log files could not be used with the
backups taken in the past. Therefore, it was historically important to take an
immediate backup as all previous backups became invalid. Using
OPEN RESETLOGS can negate the need for that backup.
Without the use of OPEN RESETLOGS, when using the RMAN catalog for future backups, the following command
had to be issued to make the RMAN catalog aware
of the new incarnation of the database.
RMAN> reset
database;
As of Oracle 10g, it is no longer necessary to back up
the database following an incomplete recovery and OPEN RESETLOGS
operations.
The OPEN RESETLOGS feature is also applicable for the
following two scenarios:
When the new database incarnation is created following the use of
OPEN RESETLOGS and the log sequence
reset, orphaned backups are created. These orphaned backups
can be used by RMAN to restore the database to a point in time not
in the current incarnation path.
It is possible for RMAN to restore backups from direct ancestor
incarnations and recover up to the current time as long as a
continuous path of archived logs exists from the earliest backups to
the desired point of recovery. This holds true even across
OPEN RESETLOGS operations.
Under certain circumstances RMAN can also perform restore
and recovery with orphaned backups via the restoration of a control
file from an appropriate incarnation.
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