Consider the following schedules involving two transactions: 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 statements is correct?
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Correct answer: D. S₁ is not conflict serializable and S₂ is
Explanation
S₁: r₁(Y) before w₂(Y) gives T1 → T2, and r₂(X) before w₁(X) gives T2 → T1, a cycle. S₂: every conflict (r₂(X)–w₁(X), w₂(Y)–r₁(Y)) gives T2 → T1, so it is equivalent to T2, T1.
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