A backup and recovery system for a relational database



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Database recovery is always of essential concern in a database processing environment. A database could be damaged in one of several ways, including system crashes, physical damage, inadvertent erasing by an operator, or by an application program error. The effect and impact of such loss on the user's installation can be minimized through the use of database recovery programs. In this thesis, the REQUEST Relational Database System is implemented to protect the database by making periodic copies of the database and by recording data changes on the log/journal tape(s). This thesis discusses the design and the implementation of REQUEST'S five utility programs: Database Image Copy Utility, Database Log/Journal Utility, Log Purging Utility, Log Cumulation Utility and Database Restore Utility. In an event of failure in the REQUEST database, the latest 'good' copy is updated with changes that have been logged in the journal since the copy was made, thus restoring the REQUEST database to its condition at the point of failure.



Database management, Electronic data processing departments--Security measures