lec32 - Bloom Filters Differential Files Simple large...

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Bloom Filters Differential Files Simple large database. Collection/file of records residing on disk. Single key. Index to records. Operations. Retrieve. Update. Insert a new record. Make changes to an existing record. Delete a record.
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Naïve Mode Of Operation Problems. Index and File change with time. Sooner or later, system will crash. Recovery => Copy Master File (MF) from backup. Copy Master Index (MI) from backup. Process all transactions since last backup. Recovery time depends on MF & MI size + #transactions since last backup. Key Index File Ans.
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Differential File Make no changes to master file. Alter index and write updated record to a new file called differential file .
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Differential File Operation Key Index File Ans. DF Advantage. DF is smaller than File and so may be backed up more frequently. Index needs to be backed up whenever DF is. So, index should be small as well. Recovery time is reduced.
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Differential File Operation Key Index File Ans. DF Disadvantage. Eventually DF becomes large and can no longer be backed up with desired frequency. Must integrate File and DF now. Following integration, DF is empty.
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Differential File Operation Key Index File Ans.
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