NIELIT 2017 July Scientist B (IT) - Section B: 56

Question

Consider the join of a relation $R$ with relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples, then the maximum size of join is

• A. $mn$
• B. $m+n$
• C. $(m+n)/2$
• D. $2(m+n)$

Answer 1

First step in join is cross product. As here there is no key constrain we can have all values same for the field we are performing join on. Hence maximum will be mn tuples.

So A is correct.

Answer 2

Answer: A  because there is no constraint  mentioned on the question that is on what attributes it has to apply thus indirectly is saying about the cross product, and we also know that 

                     Join:- Cross Product + Selection