Transaction

Let S be the following schedule of operations of three transactions T_1, T_2 \text{ and }T_3 in a relational database system:

R_2(Y), R_1(X), R_3(Z), R_1(Y)W_1(X), R_2(Z), W_2(Y), R_3(X), W_3(Z)

Consider the statements P and Q below:

P: S is conflict-serializable.
Q: If T_3 commits before T_1 finishes, then S is recoverable.

Which one of the following choices is correct?

Let r_i(z) and w_i(z) denote read and write operations respectively on a data item z by a transaction T_i. Consider the following two schedules.

S1: r_1(x)r_1(y)r_2(x)r_2(y)w_2(y)w_1(x)
S2: r_1(x)r_2(x)r_2(y)w_2(y)r_1(y)w_1(x)

Which one of the following options is correct?

Suppose a database system crashes again while recovering from a previous crash. Assume checkpointing is not done by the database either during the transactions or during recovery.

Which of the following statements is/are correct?

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?

Consider the following two statements about database transaction schedules:

I. Strict two-phase locking protocol generates conflict serializable schedules that are also recoverable.
II. Timestamp-ordering concurrency control protocol with Thomas' Write Rule can generate view serializable schedules that are not conflict serializable.

Which of the above statements is/are TRUE?

Let us assume that transaction T1 has arrived before transaction T2. Consider the schedule s=r1(A);r2(B):w2(A);w1(B)
Which of the following is true?

ACID properties of a transactions are

Which of the following concurrency control protocol ensures both conflict and free from deadlock? ,

Two transactions T_1 \; and \; T_2 are given as:

T_{1}:r_{1} (X)w_{1}(X)r_{1}(Y)w_{1}(Y)
T_{2}:r_{2}(Y)w_{2}(Y)r_{2}(Z)w_{2}(Z)

where r_{i}(V) denotes a read operation by transaction T_{i} on a variable V and w_{i}(V) denotes a write operations by transaction T_{i} on a variable V. The total number of conflict serializable schedules that can be formed by T_1 \; and \; T_2 is _____________.

In a database system, unique time stamps are assigned to each transaction using Lamport's logical clock . Let TS(T_{1}) and TS(T_{2}) be the timestamps of transactions T_{1} and T_{2} respectively. Besides, T_{1} holds a lock on the resource R, and T_{2} has requested a conflicting lock on the same resource R. The following algorithm is used to prevent deadlocks in the database system assuming that a killed transaction is restarted with the same timestamp.

Assume any transactions that is not killed terminates eventually. Which of the following is TRUE about the database system that uses the above algorithm to prevent deadlocks?