Some sample exam 2 questions: 1. Briefly define the following terms: Bulk Loading of a B+ Tree 3NF (Third Normal Form) BCNF (Boyce-Codd Normal Form) Functional dependency Lossless join decomposition Dependency preserving decomposition 2. For each of the following index methods describe (1) How the index is represented (2) Where data is stored in the index (3) How the following operations are executed searching the index for a key value insert a key value in the index deleting a key value from the index Also discuss the advantages and disadvantages of each method. The methods: ISAM B+ Trees Static Hashing Extendible Hashing Linear Hashing 3. Give an algorithm for a two-way external merge sort. How many passes would your algorithm need for a file consisting of 87 pages? 4. Give an algorithm for a n-way external merge sort. How many passes would your algorithm need for a file consisting of 87 pages when you have 15 buffers? 5. If you have a selection operator SELECT equality condition ( relation ) how would you perform the operation under the following conditions, and what would be the estimated cost of your approach in disk I/Os. - There is no index, data is unsorted - There is a clustered tree index - There is a hash index How would your answer change if the condition were not an equality condition? If there is more than one index available, how do you choose which mechanism(s) to use? 6. How is the projection operator implemented with sorting? How about hashing? What are the expected costs for these operations in terms of disk I/Os? 7. Give pseudo-code for the following join operations (you may assume the join is performed on a single attribute with an equality condition). Also give the expected cost for each operation. Simple Nested Loops Join Index Nested Loops Join Block Nested Loops Join Sort-Merge Join Hash-Join 8. What is meant by the term reduction factor? How does it apply in query evaluation? Give at least two examples of reduction factors and how they might affect a particular query. 9. System R only considers left deep plans. Why is this? Give an example of a plan that is left deep and one that is not. 10. Give an example of an optimization that might be performed on a query plan. What is the advantage of your optimization? 11. What are Armstrong's Axioms for reasoning with a set of functional dependencies? What is the closure of a set of FDs? What is the attribute closure of a set of attributes with respect to a set of FDs? 12. What do functional dependencies relate to the concept of redundancy in a database? What is our main mechanism for combatting redundancy? Give an example. 13. What is the most important thing to consider when determining whether to include an index in a database schema? Discuss some issues that should be considered for choosing to include a particular index? 14. Under what situation would you not decompose a relation that is in 3NF into a set of relations in BCNF? Discuss the factors that influence these types of decisions. 15. What is discretionary access control? Explain how discretionary access control is implemented using GRANT and REVOKE commands. 16. What is mandatory access control? How does it differ from discretionary access control? 17. Define the term transaction. What are some of the important characteristics of transactions?