A typical enterprise database is usually very large, consisting hundreds of tables. Some of the tables may be very huge, having millions of rows. It is critical to have optimum performance for any enterprise database. Our discussion this week focus on the technique how to improve access speed of the database.

Questions:

1)Why disk I/O is always a bottleneck for database performance?

2)Why do we use index to improve the table access performance?

3)If there is a small table containing only a list of 50 states, is it necessary to use index? If we do use index, will it improve or hinder the access speed?

4)A large table contains customer information from 50 states. It is decided to use index according to the states. Which type of index would be the most efficient for such application?