Question

Consider the following classes of schedules: view-serializable, conflict-serializable, recoverable, avoid-cascading-aborts, and strict. For each of the following schedules, state which of the preceding classes it belongs or does not belong to. If you cannot decide whether a schedule belongs in a certain class based on the listed actions, explain why The actions are listed in the order they are scheduled. Assume all the transactions commit. If a commit is not shown for a transaction, the schedule is incomplete. However, any commit must follow all the transactions.

a. Tu W(X) T2: R(X) W(X) W(X)
b.TI: R(Y) T2: W(X) R(X) R(Y)
c. TI: REX) T2: R(Y) W(X) T3: R(Y) R(X) W(X)
d. TI: R(X) R(Y) W(X) T2 T3 R(Y) R(Y) W(Y)
e. Ti Roxi Wixi W X) commit commit commit 13: WEX)

Answer 1

The schedules belong to different classes based on view-serializable and conflict-serializable criteria.

Step-by-step explanation:

a. The given schedule Tu W(X) T2: R(X) W(X) W(X) is not view-serializable because the order of operations does not match the order of precedence of transactions. It is also not conflict-serializable because there is a conflict between T2 and T1 for the write operation on X.

b. The given schedule TI: R(Y) T2: W(X) R(X) R(Y) is view-serializable because it follows the precedence of T1 and T2. It is also conflict-serializable because there are no conflicting operations between the transactions.

c. The given schedule TI: REX) T2: R(Y) W(X) T3: R(Y) R(X) W(X) is not view-serializable because there is a conflict between T1 and T3 for the write operation on X. It is also not conflict-serializable because there is a conflict between T1 and T3 for the read operation on X.

d. The given schedule TI: R(X) R(Y) W(X) T2 T3 R(Y) R(Y) W(Y) is not view-serializable because there is a conflict between T1 and T3 for the write operation on X. It is also not conflict-serializable because there is a conflict between T1 and T3 for the read operation on Y.

e. The given schedule Ti Roxi Wixi W X) commit commit commit 13: WEX) is view-serializable because it follows the precedence of T1 and T3. It is also conflict-serializable because there are no conflicting operations between the transactions.