Q32

MCQ2 marks, −0.67

Let $S$ be the following schedule of operations of three transactions $T_1$ , $T_2$ 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?

(A)

Both $P$ and $Q$ are true

(B)

$P$ is true and $Q$ is false

(C)

$P$ is false and $Q$ is true

(D)

Both $P$ and $Q$ are false

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