Q33

MCQ2 marks, −0.67

Consider the relation $R(P,Q,S,T,X,Y,Z,W)$ with the following functional dependencies.

PQ\rightarrow X;\quad P\rightarrow YX;\quad Q\rightarrow Y; \quad Y\rightarrow ZW

Consider the decomposition of the relation $R$ into the constituent relations according to the following two decomposition schemes. $D_1:\quad R=[(P,Q,S,T);\;(P,T,X);\;(Q,Y);\;(Y,Z,W)]$ $D_2:\quad R=[(P,Q,S);\;(T,X);\;(Q,Y);\;(Y,Z,W)]$ Which one of the following options is correct?

(A)

$D_1$ is a lossless decomposition, but $D_2$ is a lossy decomposition

(B)

$D_1$ is a lossy decomposition, but $D_2$ is a lossless decomposition

(C)

Both $D_1$ and $D_2$ are lossless decompositions

(D)

Both $D_1$ and $D_2$ are lossy decompositions

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