Consider a transaction that updates each of the 100 employees' salaries in a table (there is one row per employee)under the deferred update mode and completes after a checkpoint.The system crashes after the checkpoint.What should the recovery procedure perform to make sure the transaction completes as desired?
A) Redo from first log record
B) Redo from first log record followed by execution of the transaction again
C) Undo
D) Undo followed by execution of the transaction again

Question

Quizplus · Accepted Answer

In deferred update mode, changes are not written to the database until the transaction is committed. Since the system crashed after a checkpoint, the committed changes need to be redone from the log records to ensure all updates are applied.

Consider a Transaction That Updates Each of the 100 Employees