Question

Which of the following is used for undo operations alone?

(a) Logical logging

(b) Physical logging

(c) Physical log records

(d) Physical logging and Physical log records

The question was posed to me in my homework.

I'd like to ask this question from Lock Release and Undo Operations topic in chapter Recovery System of Database Management

Answer 1

The correct answer is (a) Logical logging

The best I can explain: 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.