undo-redo

Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery....

Consider a simple checkpointing protocol and the following set of operations in the log. (start, $$T4$$); (write, $$T4, y, 2, 3$$); (start, $$T1$$); (commit, $$T4$$); (write, $$T1,...