2 In fact, based on my extensive data collection tool experience, Oracle does not always collect and report background CPU consumption through the v$sysstat or v$sesstat views. While this can present a problem when gathering detailed data used during predictive analysis, for firefighting performance analysis, the background CPU time is not likely to be significant enough to cause a misdiagnosis.

3 Some of you reading this may feel I'm getting uncomfortably close to performance ratio analysis. I understand your concern, but considering the resulting ratios are only one small part of a solid ORTA, a complete 3-circle analysis, and no action will be taken unless your ORTA directs it, I'm not concerned, and I hope you're not either. Don't, as they say, throw the baby out with the bathwater. Percentages are a fantastic way for us to relate raw numerics from one situation to another. Don't let any disdain for ratio analysis cloud their usefulness when properly used.

4 If you really want to learn about Oracle internals, especially the internals that practical performance analysts don't care about, then become an Oracle kernel developer. But if you want to learn about internals that actually affect a DBAs work, you may be surprised to find a lot of useful information by reading Oracle patents. Yes, that is correct; patents. Now, I realize this is a little strange. But that's how I find out about how Oracle works without getting my hands on illegal proprietary information. Go to http://patft.uspto.gov/netahtml/PTO/search-bool.html and do a search with the assignee as Oracle. That will get you started! Patent information is publically available and free. Keep in mind that just because Oracle has a patent does not mean it must implement the invention in its kernel code.