MAIL-ORDER INDEX

A Virginia-based mail-order company sends out approximately 25 million catalogs each year, using a customer table with 10 million names. Although the primary key of the customer table is customer identification number, the table also contains an index of customer last names. Most people who call to place orders remember their last name, but not their customer identification number, so this index is used frequently. An employee of the company explained that indexes are critical to reasonable response times. A fairly complicated query was written to locate customers by the state in which they lived, and it took over three weeks to return an answer. A customer state index was created, and that same query provided a response in 20 minutes; that's 1512 times faster!

QUESTION:

As an analyst, how can you make sure that the proper indexes have been put in place so that users are not waiting for weeks to receive the answers to their questions?