QUESTIONS

1. Describe the following disk concepts or components.
a. Platter and recording surface.
b. Track.
c. Cylinder.
d. Read/write head.
e. Access-arm mechanism.

2. Why is it important to store files on a cylinder-by-cylinder basis?

3. Describe the four steps in the transfer of data from disk to primary memory.

4. What is a file organization? What is an access method? What do they accomplish?

5. What is an index? Compare the concept of the index in a book to an index in an information system.

6. Describe the idea of the simple linear index. What are its shortcomings?

7. What is an indexed-sequential file?

8. Describe the idea of the B+-tree index. What are its advantages over the simple linear index?

9. Describe how a direct search works using a B+-tree index.

10. Describe what happens to the index tree when you insert new records into a file with a B+-tree index.

11. Answer the following general questions about indexes:

a. Can an index be built over a non-unique field?
b. Can an index be built over a field if the file is not stored in sequence by that field?
c. Can an index be built over a combination of fields as well as over a single field?
d. Is there a limit to the number of indexes that can be built for a file?
e. How is an index affected when a change is made to a file? Does every change to a file affect every one of its indexes?
f. Can an index be used to achieve sequential access? Explain.

12. Describe the idea of the hashed file. What are its advantages and disadvantages in comparison to indexes?

13. Describe how a direct search works in a hashed file using the division-remainder method of hashing.

14. What is a collision in a hashed file? Why do collisions occur? Why are they of concern in the application environment?

15. What is physical database design?

16. Describe why physical database design is necessary.

17. Explain why the need to perform joins is an important factor affecting application and database performance.

18. Why does the degree to which data is dispersed over a disk affect application and database performance?

19. Explain why the volume of data access operations can adversely affect application and database performance.

20. Which "input" is the starting point for physical database design?