5-User Managed Incomplete Recovery

5-User Managed Incomplete Recovery - User Managed...

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User Managed Incomplete Recovery Presenter Tathagata Bhattacharjee
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Objectives After completing this lesson, you should be able to do the following: Describe the steps of incomplete recovery Perform an incomplete database recovery Identify the loss of current online redo log files
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Incomplete Recovery Overview Incomplete recovery reconstructs the database to a prior point in time This situation results in the loss of data from transactions committed after the time of recovery. This data need to be reentered manually if required Perform this recovery only when absolutely necessary Incomplete recovery can be difficult and time- consuming
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User-Managed Incomplete Recovery Tathagata Bhattacharjee To perform incomplete recovery, you need: A valid offline or online backup of all datafiles made before the recovery point All archived logs from the backup until the specified time of recovery
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Situations Requiring Incomplete Recovery Complete recovery fails because an archived log is lost All unarchived redo log files and a datafile are lost User error An important table was dropped Invalid data was committed Current control file is lost and a backup control file must be used to open the database
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Types of Incomplete Recovery There are three types of incomplete recovery: Time-based recovery Cancel-based recovery Change-based recovery
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User-Managed Incomplete Recovery Tathagata Bhattacharjee You may need to recover using a restored control file when: Control files are lost Performing incomplete recovery to a point when the database structure is different than the current
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Time-Based Recovery This method of recovery is terminated after all changes up to a specific point in time are committed. Use this approach when: Unwanted changes to data were made or important tables dropped, and the approximate time of the error is known. Recovery time and data loss will be minimized if you are notified immediately The approximate time a nonmirrored online redo log becomes corrupt.Mirroring of logs should prevent the need for this type of recovery
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User-Managed Incomplete Recovery Tathagata Bhattacharjee Cancel-Based Recovery This method of recovery is terminated by entering CANCEL at the recovery prompt (Instead of a log file name). Use this approach when: A current redo log file or group is damaged and is not available for recovery. Mirroring should prevent the need for this type of recovery
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5-User Managed Incomplete Recovery - User Managed...

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