11. Consider a DBMS using ARIES protocol for logging records with the following format of log records:

The log can contain checkpoint begin, checkpoint end, transaction begin, transaction commit, transaction end and undo action records.

Assume below is what DBMS retrieve in the log after a crash:

1

2

3

4

5

6

7

8

9

Answer the following questions assuming that there is no dirty pages nor active transactions during the checkpoint:

(a) Which transaction(s) will -possibly- be undone? (b) Assume that all the dirty pages have been flushed to disk after the successful recovery comple-

tion. What will be the values of data objects A, B, C and D on disk?

(c) After the the successful recovery completion, what will be the contents of the log? (write the log records after the crash.)