MadeEasy Subject Test: Databases - Timestamp Ordering

Question

Answer 1

In above problem TS(t2) < TS(t3) < TS(t1) 

So, According to time stamp protocol if any type of conflict occurs, it should be from t2 to t3 or t3 to t1. But in above there is an conflict $r1(x) \rightarrow w3(x)$ which is not allowed by Time stamp protocol.

But if there is a Write---Write conflict, it can still be allowed by changing writing order according to Thomas Write Rule.

But In above question there is a Read - Write Conflict from T1 to T3. So, even Thomas write Rule doesn't allow this.

So, answer should be option C

Comments

TS(t2) < TS(t3) < TS(t1)

since it is given (30, 10 ,20)

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sorry:) Updated:)

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I am not sure about the selected answer, can anybody please verify?
It would be allowed by TWR and correct option is B.

The equivalent serial schedule would be as below:

T1	T2	T3
	R(Y)
	R(Z)
		R(Y)
		W(X)
R(X)
W(X)
W(X)