Consider a very different situation. Johnny has grown up and is now an adult, John. John is not feeling well, so he visits his doctor. The doctor asks John where it hurts, and John responds by moving his elbow and saying, "It hurts when I do this!" The doctor then responds by telling John to stop moving his elbow and escorts him out of her office. No, just joking. Because John told the doctor specifically about the pain, the doctor runs a few very isolated tests. She then will say something like, "Based on what you told me, the few isolated tests I ran, my years of experience, and my in-depth knowledge of the human body, this is the problem and this is what you need to do."

What a difference a few years can make, eh? The key difference is that John can tell the doctor where the pain is. This is just like Oracle's wait interface telling you where the pain is, where the contention is, and where too much time is being spent. Ratio analysis is like diagnosing Johnny, whereas wait-event analysis is like working with John-a much faster, more precise, and more confident diagnosis.

* First, the doctor must know John's language and be able to listen to him. This is just like a firefighter knowing how to listen to Oracle, through Oracle's wait interface. This book will teach you how to listen to Oracle. But this is just the start.