Author: Aron Kenny

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It is very important to backup and recover your Oracle databases from time to time so as to protect your data from corruptions, hardware failures, and data failures. Although Oracle provides a number of great features for protecting your data but you should make sure that you have a valid and up to date backup of your database each time.

Being database administrator you must have experienced a number of scenarios where you need to backup your Oracle databases. Which type of recovery you should attempt depends on the situation. For example consider a situation where someone dropped a table and one of one of the online redo logs is missing and is not archived and the table needs to be recovered. Another case is where your backup control file does not know anything about the arhivelogs that got created after your last backup. Similarly another scenario can be where you have lost all logs pass a specific sequence say X and you want to control which archived log terminates recovery. Or a scenario where one of the archived redo log files required for the complete recovery is corrupt or missing and the only recovery option is to recover up to the missing archived redo log file. And the list goes on and on…..

Oracle Cancel-Based Recovery:

Oracle Cancel-Based Recovery is basically a user managed incomplete recovery where you use the UNTIL CANCEL clause to perform recovery until the user manually cancels the recovery process. Oracle Cancel-Based Recovery is usually performed when there is a requirement to recover up to a particular archived redo log file. All recovery scenarios we discussed above need Oracle Cancel-Based Recovery.

The Oracle Cancel-Based Recovery process prompts user with the suggested archived redo log files' names and is stopped when the user specifies CANCEL instead of specifying an archived redo log file's name. If the user does not specify CANCEL then the recovery process will automatically stop when all redo has been applied to the datafiles.

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