Suppose that a data warehouse for Big-University consists of the following four dimensions: student, course, semester, and instructor, and two measures count and avg grade. When at the lowest conceptual level (e. g., for a given student, course, semester, and instructor combination), the avg grade measure stores the actual course grade of the student. At higher conceptual levels, avg grade stores the average grade for the given combination.
(a) Draw a snowflake schema diagram for the data warehouse.
(b) Starting with the base cuboid [student, course, semester, instructor], what specific OLAP operations (e. g., roll-up from semester to year) should one perform in order to list the average grade of CS courses for each Big-University student.