Advanced Databases / Data Distribution System

Use the data distribution scheme for a distributed University example described below.

A University has multiple locations across a wide geographic area (large city?). There are servers located at each of the five campuses (North, South, East, West, and Main campuses).

Each of the campuses is connected to the University network. The servers at each site contain the following tables: Student, Faculty, Class, and Enroll. The primary copy of the Enroll table is on the Main campus server; secondary copies of the Enroll table exist on the North, South, East and West campus servers.

1) Describe two strategies for this query: Find the ClassNumber and the names of all students enrolled in all classes with schedule MWF9.

2) Describe two strategies for this query: Find the ClassNumber, facId of the teacher, and the campus of all classes being taken by RosemaryHughes, who is a student at the North campus.

3) Consider the query "Find the ClassNumber, schedule, and lastName of all enrolled students for all classes being taught by Professor Smith of the North campus." The query is entered at the North campus. Describe a strategy that does not use the semijoin.

4) Consider the query "Find the ClassNumber, schedule, and lastName of all enrolled students for all classes being taught by Professor Smith of the North campus." The query is entered at the North campus. Describe a strategy that does use a semijoin.

North Site StudentNorth Faculty North Enroll North (secondary) Class Network East Site Studentpast FacultyEast Enrollast (secondary) Class West Site StudentWest Faculty West Main Site StudentMain FacultyMairn Class Enroll (primary) EnrollwWest (secondary) Class South Site Studentsouth Facultysouth Enrollsouth (secondary) Class