11. Consider a DBMS using ARIES protocol for logging recordswith the following format of log records:
<transactionID, variable, beforeValue, afterValue>
The log can contain checkpoint begin, checkpoint end,transaction begin, transaction commit, transaction end and undoaction records.
Assume below is what DBMS retrieve in the log after a crash:
1 <BEGIN CHECKPOINT>
2 <END CHECKPOINT>
3 <T1, A, 10, 20>
4 <T2, B, 30, 40>
5 <T1 COMMIT>
6 <T1 END>
7 <T3, C, 50, 60>
8 <T4, D, 50, 60>
9 <T2 COMMIT>
Answer the following questions assuming that there is no dirtypages nor active transactions during the checkpoint:
(a) Which transaction(s) will -possibly- be undone?
(b) Assume that all the dirty pages have been
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