Transaction

Let R_i(z) and W_i(z) denote read and write operations on a data element z by a transaction T_i, respectively. Consider the schedule S with four transactions.

S: R_4(x)R_2(x)R_3(x)R_1(y)W_1(y)W_2 (x)W_3 (y)R_4(y)

Which one of the following serial schedules is conflict equivalent to S?

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 _____________.