Exercise 12.1 Briefly answer the following questions: Describe three techniques commonly u...

Exercise 12.1 Briefly answer the following questions:

1. Describe three techniques commonly used when developing algorithms for relational operators. Explain how these techniques can be used to design algorithms for the selection, projection, and join operators.
2. What is an access path? When does an index match an access path? What is a primary conjunct, and why is it important?
3. What information is stored in the system catalogs?
4. What are the benefits of storing the system catalogs as relations?
5. What is the goal of query optimization? Why is optimization important?
6. Describe pipelining and its advantages.
7. Give an example query and plan in which pipelining cannot be used.
8. Describe the iterator interface and explain its advantages.
9. What role do statistics gathered from the database play in query optimization?
10. What were the important design decisions made in the System R optimizer?
11. Why do query optimizers consider only left-deep join trees? Give an example of a query and a plan that would not be considered because of this restriction.