Database Systems 6th Edition by Ramez Elmasri, Shamkant B. Navathe

Exercise 9

Consider the three transactions T₁(X), T₂(X), and T₃(X), and the schedules S1 and S2 given below. Draw the serializibility (precedence) graphs for S1 and S2 and state whether each schedule is serializable or not. If a schedule is serializable, write down the equivalent serial schedule(s).
T₁(X): r₁(X); r1(z); w₁(X)
T₂(X): r2(z); r₂(y); w2(z); w₂(y)
T₃(X): r₃(X); r₃(y); w₃(y)
S1: r₁(X); r2(z); r₁(X); r₃(X); r₃(y); w₁(X); w₃(y); r₂(y); w2(z); w₂(y)
S2: r₁(X); r2(z); r₃(X); r1(z); r₂(y); r₃(y); w₁(X); w2(z); w₃(y); w₂(y)