1. Query processing (8 points) Suppose we have the following relational schema: Courses(course:string, credits:integer) Enrolled(sid:integer, course:string, semester:string) Also suppose there are hash indexes on Students.sid, Enrolled.sid, and Enrolled.course. Describe how you would compute each operation in the query execution tree below. For each operation, provide an algorithm name or write "on the fly". Indicate whether the results of the operation will be materialized to disk or pipelined to the next operation. Be sure to indicate where indexes are used