Answer to Question #269965 in Databases | SQL | Oracle | MS Access for Tarurendra Kushwah

Question

Check whether the given schedules are conflict serializable or not

 S1 : R2(B)W2(A)R1(A)R3(A)W1(B)W2(B)W3(B)

S2:R3(Y)W3(Z)R1(X)W1(X)W3(Y)W3(Z)R2(Z)R1(Y)W1(Y)R2(Y)W2(Y)

Answer 1

Precedence Graph is used to tell if the schedules are conflict serializable or not:

Schedule S1:

 S1: R2(B)W2(A)R1(A)R3(A)W1(B)W2(B)W3(B).

Schedule S1 is not conflicted serializable because there is a circle in the precedence graph.

Schedule S2:

S2:R3(Y)W3(Z)R1(X)W1(X)W3(Y)W3(Z)R2(Z)R1(Y)W1(Y)R2(Y)W2(Y)

Schedule S2 is conflicted serializable because there is no circle in the precedence graph.