The kind of Oracle internals information I’ve included in this book is not readily available to customers. Because I have never been an Oracle insider, the material in this book has had to be compiled the hard way. I began by studying the structure and contents of the X$ tables, and poring over trace files. I then formulated hypotheses and tested them. Because of this approach, it is likely that some of my conclusions about how things work are wrong, and that some of my suggestions are misguided, or applicable only under limited conditions. So, the onus is on you to test everything for yourself. If you find any errors, please email me so that they can be corrected (see “Comments and Questions”).
You should also note that this book goes boldly where Oracle Support fears to tread. I explain and at times recommend the use of various undocumented features that I find essential to advanced performance tuning. However, Oracle has chosen to leave those same features undocumented—presumably with valid reasons. So please don’t expect Oracle to assist you in their use. Try them by all means, but if you have a problem, quit. Don’t bother Oracle Support about it.
Finally, please note that this book is oriented towards Oracle8i, release 8.1. Although most of the material is applicable to earlier releases as well, some of it is not. In particular, there have been major changes in Oracle Parallel Server in both the 8.0 and 8.1 releases, and a number of the parameters have been hidden in release 8.1.