Consider the relations r1(A, B, C), r2(C, D, E) and r3(E, F). Assume that the set of all attributes constitutes the primary keys of these relations, rather than the individual ones. Let V (C, r1) be 500, V (C, r2) be 1000, V (E, r2) be 50, and V (E, r3) be 150, where V (X, r) denotes the number of distinct values that appear in relation r for attribute X . If r1 has 1000 tuples, r2 has 1500 tuples, and r3 has 750 tuples, then give the ordering of the natural join of r1, 2 and r3 for its efficient computation. Justify your answer.
