Consider the relation R(P, Q, S, T, X, Y, Z, W) with the following functional dependencies.
PQ → X; P → YX; Q → Y; Y → ZW
Consider the decomposition of the relation R into the constituent relations according to the following two decomposition schemes.
D1 : R = [(P, Q, S, T); (P, T, X); (Q, Y); (Y, Z, W)]
D2 : R = [(P, Q, S); (T, X); (Q, Y); (Y, Z, W)]
Which one of the following options is correct?
Let ri(z) and wi(z) denote read and write operations respectively on a data item z by a transaction Ti. Consider the following two schedules.
S1 : r1(x) r1(y) r2(x) r2(y) w2(y) w1(x)
S2 : r1(x) r2(x) r2(y) w2(y) r1(y) w1(x)
Which one of the following options is correct?
Assume that a 12-bit Hamming codeword consisting of 8-bit data and 4 check bits is d8d7d6d5c8d4d3d2c4d1c2c1, where the data bits and the check bits are given in the following tables:
Data bits |
|||||||
d8 |
d7 |
d6 |
d5 |
d4 |
d3 |
d2 |
d1 |
1 |
1 |
0 |
x |
0 |
1 |
0 |
1 |
c8 |
c4 |
c2 |
c1 |
Y |
0 |
1 |
0 |
Which one of the following choices gives the correct values of x and y?