The Most Common Database Design Mistakes - Too Much, Too Little, Too Late
Experts say that developers often use too many or too few indexes, both of which are bad for performance. The trick is to measure your performance: A simple query analysis often can tell you what you need to know to decide how many indexes are needed; other times, you may have to examine the overall server performance and how it's affected by the locking of specific indexes under load.
The job of developing a database is not easy, which is why more people don't/can't do it. That said, even the experts make mistakes in the process. After soliciting input from analysts and some professionals in the field, eWEEK has compiled a list of some of the more common database design mistakes and a few general tips for avoiding them.