Explanation:Undo erases all the changes and redo makes the deleted changes. 9. For correct behaviour during recovery, undo and redo operation must be
A. Commutative
B. Associative
C. Idempotent
D. Distributive
Answer:A
Explanation:Undo erases all the changes and redo makes the deleted changes. 9. For correct behaviour during recovery, undo and redo operation must be
A. Commutative B. Associative C. Idempotent D. Distributive
Explanation:Undo erases all the changes and redo makes the deleted changes. 10. If ___________ are not obtained in undo operation it will cause problem in undo-phase.