Database Management System
Q191.
Which of the following concurrency control protocols ensure both conflict serializability and freedom from deadlock? I. 2-phase locking II. Time-stamp orderingQ193.
Consider a schedule of transactions T1 and T2: Here, RX stands for "Read(X)" and WX stands for "Write(X)". Which one of the following schedules is conflict equivalent to the above schedule?Q194.
Which of the following scenarios may lead to an irrecoverable error in a database system?Q195.
Consider two transactions T1 and T2, and four schedules S1, S2, S3, S4 of T1 and T2 as given below: T_{1}:R_{1}[x]W_{1}[x]W_{1}[y] T_{2}:R_{2}[x]R_{2}[x]W_{1}[y] S_{1}:R_{1}[x]R_{2}[x]R_{2}[y]W_{1}[x]W_{1}[y]W_{2}[y] S_{2}:R_{1}[x]R_{2}[x]R_{2}[y]W_{1}[x]W_{2}[y]W_{1}[y] S_{3}:R_{1}[x]W_{1}[x]R_{2}[x]W_{1}[y]R_{2}[y]W_{2}[y] S_{4}:R_{2}[x]R_{2}[y]R_{1}[x]W_{1}[x]W_{1}[y]W_{2}[y] Which of the above schedules are conflict-serializable?Q196.
Which of the following contains complete record of all activity that affected the contents of a database during a certain period of time?Q197.
Consider the following three schedules of transactions T1, T2 and T3. [Notation: In the following NYO represents the action Y (R for read, W for write) performed by transaction N on object O.]\begin{array}{lllllllllll} \hline(S 1) & 2 R A & 2 W A & 3 R C & 2 W B & 3 W A & 3 W C & 1 R A & 1 R B & 1 W A & 1 W B \\ \hline(S 2) & 3 R C & 2 R A & 2 W A & 2 W B & 3 W A & 1 R A & 1 R B & 1 W A & 1 W B & 3 W C \\ \hline(S 3) & 2 R A & 3 R C & 3 W A & 2 W A & 2 W B & 3 W C & 1 R A & 1 R B & 1 W A & 1 W B \\ \hline \end{array}Which of the following statements is TRUE?Q199.
Amongst the ACID properties of a transaction, the 'Durability' property requires that the changes made to the database by a successful transaction persistQ200.
Consider the following log sequence of two transactions on a bank account, with initial balance 12000,that transfer 2000 to a mortgage payment and, then apply a 5% interest. 1. T1 start 2. T1 B old = 12000 new = 10000 3. T1 M old = 0 ne = 2000 4. T1 commit 5. T2 start 6. T2 B old = 10000 new = 10500 7. T2 commit Suppose the database system crashed just before log record 7 is written. When the system is restarted, which one statement is true of the recovery procedure?