Oracle performance analysis is about solving real-life production performance issues. In all my years of using Oracle's instrumentation, Oracle has not misled me in my analysis. The OraPub 3-circle analysis has confirmed and strengthened what Oracle's instrumentation has indicated. This is why I don't get uptight about unaccounted time. My job is to fix real performance issues, not to find the missing 50 ms!

Sure, it's a lot of fun to figure out the response time to the minutia level, and it definitely is good for your image and makes great cocktail party conversations, but the value of this missing time is highly questionable. During a firefight, it's easy to get distracted from the main overriding goal, and trying to account for every microsecond can cause the technical problem solver to stray from the main objective.

Understanding how Oracle collects time is not only fascinating, but it also gives you a greater appreciation for the Oracle wait interface. You'll have a better idea of how the wait interface works, which provides you with a higher level of confidence during analysis and when presenting your results. You will also begin to use the instrumentation in creative and highly effective ways.