transactions

Question

schedule

R(A)
	R(B)
R(B)
W(A)
COMMIT
		R(C)
		R(B)
		W(C)
	W(B)
	R(A)
	R(C)
	COMMIT
		COMMIT

The above scedule is -:

a)conflict serializable

b)recoverable

c)cascadeless

d)all of these

according to me a)&b)

answer given -:a)

Answer 1

it is Conflict Serial as T₁ ---> T₃ ---> T2 or T₃ ---> T₁ ---> T₂ .
But Schedule is Irrecoverable bcoz of Dirty Read :  W₃(C) and R₂(C) and T₂ commit before T_3.

Comments

T2 is reading C written by T3 so T3 must commit before T2 so its not recoverable ..isn't it?

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yes !!!