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This post addresses reprocessing and two-phase locking.

Question 1.
Distinguish between reprocessing and rollforward as database recovery techniques.

Question 2.
Discuss the strategy of two-phased locking. Use examples to help explain the concept.

Solution Preview

Question 1.
Distinguish between reprocessing and rollforward as database recovery techniques.
In reprocessing, the database is recovered from backups that have been saved since the last time of regular backup by the company. This is an ideal database recovery technique because "if the system crashes, the latest database save is restored and all of the transactions are reapplied to bring the database back up to the point just before the crash" (CUNY.edu, 2012). Although there is some work involved in bringing the system current from the time of the crash to the present moment because some data will be lost after the restore, it is a very effective method for database recovery. In contrast, a roll-forward database recovery technique brings the database back to the current state pre-crash, by redoing all completed transactions and storing the completed transactions into a separate log file on a part of the database where backups are stored.

A roll-forward recovery is used when "the transaction log ...

Solution Summary

The solution provides a very detailed examination of the two following questions:
Question 1.
Distinguish between reprocessing and rollforward as database recovery techniques.

Question 2.
Discuss the strategy of two-phased locking. Use examples to help explain the concept.

APA references are also provided.

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