Exam-style question
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Compare serialisation, timestamp ordering and commitment ordering as methods for controlling concurrent access to a client server database. Your answer should explain how each method can help preserve database integrity.
Model answer
What a good answer should say
- Serialisation makes concurrent operations follow a defined sequence, so their effects are applied in an ordered way rather than allowing conflicting operations to be applied unpredictably.
- Timestamp ordering uses timestamps to establish the order in which operations should be processed.
- Operations that do not follow the required timestamp order are controlled so that the agreed order is maintained.
- Commitment ordering controls the order in which operations are committed, ensuring that the final acceptance of changes follows an appropriate order.
Explanation
Why this works
A strong comparison explains the controlling principle of each method: serialisation orders operations, timestamp ordering uses timestamps to order them, and commitment ordering controls the order of commitment. The answer also connects each method to preserving integrity during simultaneous access.
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