Without further note, the ˇ°Slideˇ± will mean the slide of concurrency.
1.What is the relationship between serial schedule, serializable schedule and conflict serializable schedule?
Hint: From the definitions of these concepts which can be found from the slides P5, P10 and P11, you can find that conflict serializable schedules are just a subset of the serializable schedules. In fact, there is another kind of serializable schedule called view serializable schedules which has a looser limitation compared to conflict serializable schedule. Both of them are serializable schedules.
Serial schedules are the optimal situation for the transaction management. All the technologies we have mentioned in the lecture are aimed to convert a conflict schedule into a serial schedule, and these two schedules are conflict equivalent.
2.Show examples for the three kinds of anomalies in the interleaved transaction execution.
Hint: Slide P6, P7.
3.What is the difference between 2PL and strict-2PL?
Hint: Strict-2PL are used to prevent the possible cascading aborts problem in 2PL protocol. For this purpose, strict-2PL adds one more limitation on the release of the exclusive lock, compared to the common 2PL.
4.Can 2PL prevent deadlock? How about strict-2PL?
Hint: Both of the protocols are focusing on the transaction management when there are conflicts when two transactions try to use one same resource, but an simple example of deadlock can be made on two transactions with two resources(review the example we used in the lecture for deadlock on the blackboard).
5.What is the purpose of the intension locks? Draw the conflict table for S, X, IS, IX, SIX.
Hint: See the correction mail about SIX and also Slide P18-P24.