How many times have you been asked, "So what kind of performance improvement can we expect?" It's an honest and painfully practical question, which deserves an honest answer. Unfortunately, while Oracle professionals are proficient in many areas, one area where there is a glaring gap is in understanding the impact of their proposed performance solutions. The skill required to answer this question requires deep Oracle performance analysis proficiency.

This chapter's coverage borders on predictive performance analysis and some serious mathematics, yet I'll keep focused on simplicity, practicality, and value (for example, I will limit the number of Greek symbols and mathematical formulas to the absolute bare minimum). Furthermore, I will always tie the analysis back to the fundamentals: an Oracle response-time analysis, OraPub's 3-circle analysis, and solid Oracle internals knowledge. I do not intend to explain how to plan IT architectures. My goal is to provide substance, conviction, and useful information, and to motivate change toward scientifically ranking the many possible performance-enhancing solutions.

All anticipatory performance questions require a solid grasp of response-time analysis, which is the first topic of this chapter. The good news is that if you have a solid understanding of the topics covered in the first few chapters, you are adequately prepared. (If you just opened this book, I highly recommend you review those first few chapters, as they set the foundation for this chapter.) Next, I'll present a fundamental and surprisingly flexible concept commonly called utilization. Response-time analysis combined with a solid grasp of utilization will prepare you for the next topic, which is understanding the various ways our solutions influence performance. Finally, we'll dive into anticipating our solution's impact in terms of time and utilization. To ensure you can do everything presented in this chapter, I will provide a number of examples. That's a tall order for a single chapter, so let's get started!