UGC-NET | UGC-NET CS 2017 Nov – III | Question 7
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 ?
S1: r1(X); r2(X); w1(X); r3(X); w2(X) S2: r2(X); r1(X); w2(X); r3(X); w1(X) S3: r3(X); r2(X); r1(X); w2(X); w1(X) S4: r2(X); w2(X); r3(X); r1(X); w1(X)
(A) S1
(B) S2
(C) S3
(D) S4
Answer: (D)
Explanation: We can draw precedence graph for each schedule and for conflict serializability graph must not contain cycle.
Refer:Gate_CS 2014
So, option (D) is correct.
Quiz of this Question
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