Gate2020 cs Q61

61Consider a schedule of transactions T₁ and T₂:

T₁	RA			RC		WD		WB	Commit
T₂		RB	WB		RD		WC			Commit

Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one following schedules is conflict equivalent to the above schedule?

Option : D
Explanation :
R₂(B) is conflicting with W₁(B) so, W₁(B) should always come after R₂(B)
W₂(B) is conflicting with W₁(B) similarly, W₁(B) should always come after W₂(B)
R₂(D) is conflicting with W₁(D), so, W₁(D) should always come after R₂(D)
R₁(C) is conflicting with W₂(C) so, W₂(C) should always come after R₁(C)
Therefore the transaction will be:
T1 T2
R(B)
W(B)
R(D)
R(A)
R(C)
W(D)
W(B)
W(C)
Commit
Commit

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