Explanation: It is important that the lower-level locks acquired during an operation are sufficient to perform a subsequent logical undo of the operation. 3. Which of the following is used for undo operations alone ?
A. Logical logging
B. Physical logging
C. Physical log records
D. Both b and c
Answer:A
Explanation: It is important that the lower-level locks acquired during an operation are sufficient to perform a subsequent logical undo of the operation. 3. Which of the following is used for undo operations alone ?
A. Logical logging B. Physical logging C. Physical log records D. Both b and c
Explanation: If the operation inserted an entry in a B+-tree, the undo information U would indicate that a deletion operation is to be performed, and would identify the B+-tree and what entry to delete from the tree. Such logging of information about operations is called logical logging. 4. Redo operations are performed exclusively using