Database Reference
In-Depth Information
The purpose of Redo Log files is now clear that it helps Oracle
in bringing the database to the last committed transaction before
the time failure occurred otherwise if there would not be any
Redo Logs then would have recovered the database to the last
good backup and things or in other words transactions that took
place after the backup would then be lost.
If you use just RECOVER DATABASE, then this is considered
as complete recovery where as if we use the clause UNTIL
TIME/UNTIL CANCEL/UNTIL CHANGE with the RECOVER
DATABASE statement then we can stop the process of recovery
in the middle. This concept applies to both User-Managed and
RMAN based.
After any type of incomplete recovery, a complete database
backup must be performed. In case of time based recovery we
can stop the recovery process at any point in time after the last
backup but before the time of failure. So instead of just using
RECOVER DATABASE, add the UNTILL TIME clause to it as
shown below.
RECOVER DATABASE
UNTIL TIME '2004-2-15 11:00:00';
The complete name of such type of recovery is “User-Managed
Time-Based Incomplete Recovery” or simple “Time Based”
recovery.
In “Cancel-Based” recovery, you Oracle will ask you each time
its going to apply the redo log file whether to apply it or not. It's
more like a yes/no question. If you press the Enter key, the redo
log will get applied and Oracle will ask you again regarding the
next redo log file i.e. whether you want to apply the redo log file
or not. If you press Enter, Oracle will apply that redo log file
again. This process is repeated again and again unless you enter
the CANCEL command or all the redo log gets applied. If you
respond with the CANCEL command then Oracle will not apply
that redo log file and will stop the recovery process. The
statement used to perform such type of recovery is as follows.
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