The undo and redo operations must be _________ to guarantee correct behaviour, even if a failure occurs during recovery process.
A. idempotent
B. easy
C. protected
D. All of these
Answer:A
The undo and redo operations must be _________ to guarantee correct behaviour, even if a failure occurs during recovery process.
A. idempotent B. easy C. protected D. All of these
Explanation: Idempotent – Multiple executions of an operation have the same result as does one execution.