Interesting yet not useful Oracle internals are simply not covered. Just how deep do we go into Oracle internals? This is a question I grapple with daily. Everyone involved with Oracle, from the kernel architect to the businessperson, abstracts Oracle internals in some way. Since each of us has limited time and specific responsibilities, it behooves us to go only as deep as we must and abstract wherever we can. So, I only go as deep into the internals as necessary to clearly diagnose the problem, arrive at solutions, and communicate my work to others (both the technical and the nontechnical). This means I miss out on certain cocktail party conversations, but I can cover a much larger breadth of technology and get the job done.

One of the frustrating parts of my work is when people (and sometimes students) want nothing but Oracle internals knowledge. Without exception, they are the ones who, when faced with a case study or a real Oracle system, stare at the screen wondering where to start, spend time on nonproductive analysis, and have extreme difficulty communicating to others what they are doing and why they are doing it. Therefore, in this book, I will take the liberty to abstract where I feel it is best for real-life production Oracle database system performance analysis.

In this book, references to methodology, performance diagnosis, and communication apply to all Oracle versions since Oracle 6. They are not affected by Oracle version changes. This is great news, because it allows a consistent and proven approach that spans time. And we'll use that to our advantage!