a design a query plan for the following

Question

(a) Design a query plan for the following distributed query: An application at site B wants to compute a join of STUDENT ?_Id=StudId TRANSCRIPT where STUDENT (Id,Major) is at site B and TRANSCRIPT (StudId, CrsCode) is at site C. The result should be returned to B. Assume that semijoin is not used. Also assume that

• Value lengths are:

1. Id and StudId are 8 bytes long;
2. Major is 3 bytes long;
3. CrsCode is 6 bytes long.

• STUDENT has 15,000 tuples.
• 6,000 students are registered for at least one course. On the average, each student is registered for 5 courses.

(b)   Estimate the cost of computing σ_Major='CS' (STUDENT) ?_{Id = StudId} TRANSCRIPT using the semijoin strategy. Use the sizes of the STUDENT and TRANSCRIPT relations and of their attributes from the part (a) above. In addition, assume that 10% of the students major in CS. Compare this with the solutions in part (a) above that do not use the semijoin.