Chapter 16, Problem 5PE

Explanation of Solution

To estimate the size of the r1 |><| r2 |><| r3:

• The given relations are,
  • r1(A,B,C)
  • r2(C,D,E)
  • r3(E,F)
• The above relations r1, r2, and r3 having the primary keys “A”, “C” and “E” respectively.
• In relational algebra, the associative and communicative properties are exhibited using joins.
• Hence, joining thee relations produce the same result.
• The required size is computed as follows,
  • Perform the join of relation r1 with r2, and this result will contain 1000 records as “C” is the primary key or relation r2 and is common in two relations r1, and r2.
  • Next, perform the join operation of relation r3 with the above result and this result will contain 1000 records as “E” is the primary key for the relation r3 and is common in two relations...