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What is the purpose of a Compensation Log Record (CLR) in ARIES?
Ato record committed transactions for redo
Bto mark the start of a new transaction
Cto record undo so recovery itself is crash-safe
Dto compress the log by removing old records
Answer & Solution
Correct answer: C. to record undo so recovery itself is crash-safe
When ARIES undoes an action during the Undo pass, it writes a CLR describing the undo. If the system crashes again mid-recovery, the next recovery sees the CLR and skips that undo. This makes ARIES recovery idempotent: it can survive crashes during recovery, which is a real concern for long undo passes.
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