Consider the following read-write schedule $S$ over three transactions $T_{1}$, $T_{2}$, and $T_{3}$, where the subscripts in the schedule indicate transaction IDs:
$S: r_{1}(z); w_{1}(z); r_{2}(x); r_{3}(y); w_{3}(y); r_{2}(y); w_{2}(x); w_{2}(y);$
Which of the following transaction schedules is/are conflict equivalent to $S$?
Let Ri(z) and Wi(z) denote read and write operations on a data element z by a transaction Ti, respectively. Consider the schedule S with four transactions.
S : R4(x), R2(x), R3(x), R1(y), W1(y), W2(x), W3(y), R4(y)
Which one of the following serial schedules is conflict equivalent to S?
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?
Let ri(z) and wi(z) denote read and write operations respectively on a data item z by a transaction Ti. Consider the following two schedules.
S1 : r1(x) r1(y) r2(x) r2(y) w2(y) w1(x)
S2 : r1(x) r2(x) r2(y) w2(y) r1(y) w1(x)
Which one of the following options is correct?