Q29

MCQ2 marks, −0.67

Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item x, denoted by $r(x)$ and $w(x)$ respectively. Which one of them is conflict serializable?

(A)

$r_1(x)$ ; $r_2(x)$ ; $w_1(x)$ ; $r_3(x)$ ; $w_2(x)$ ;

(B)

$r_2(x)$ ; $r_1(x)$ ; $w_2(x)$ ; $r_3(x)$ ; $w_1(x)$ ;

(C)

$r_3(x)$ ; $r_2(x)$ ; $r_1(x)$ ; $w_2(x)$ ; $w_1(x)$ ;

(D)

$r_2(x)$ ; $w_2(x)$ ; $r_3(x)$ ; $r_1(x)$ ; $w_1(x)$ ;

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