It is a database questions talks about transactions.

PL-phase locking

BTO- Basic Timestamp Ordering

2) there are schedules that are possible under 2PL but are not possible under BTO. Suppose we have the following schedule.

Step T0 T1

1 lock(A)

2 read(A)

3 lock(B)

4 write(B)

5 unlock(B)

6 lock(B)

7 read(B)

8 unlock(A)

9 unlock(B)

10 lock (C)

11 read (C)

12 unlock(C)

(a) Is this schedule allowed in the 2PL? Why (explain briefly)?

(b) Is this schedule allowed in BTO where TS (T0) =12, TS(T1)=11 (if not, explain briefly)?

3.(8 points) Consider the following actions taken by transaction T1 on databases X and Y items: R(X), W(X), R(Y), W(Y).

(a)Give an example of another transaction T2 that, if run concurrently to transaction T1 without some form of concurrency control, could interfere with T1.

(b)Explain how the use of Strict 2PL would prevent interference between the two transactions.

4. (5 points) What is the CAP theorem? Furthermore, what are the similarities and differences between consistency used in CAP versus Consistency used in ACID?