Every month, beginning next month, The Specialist will present a fresh installment of the Performance Tuning by Example series of case studies created by the Database Specialists team. Here is an introduction to the systematic methodology used in each case study.

1. The first step is to define the problem. This requires patient listening, skillful questioning, and even careful observation. "The database is slow" is an example of a poorly defined problem. "The database is slow between 10 a.m. and 11 a.m. every day" is more precise. "This report now takes twice as long as it used to take only a week ago" is another example of a precisely defined problem.
2. The second step is to investigate the problem and collect as much pertinent evidence as possible. Examples include Statspack reports, "sar" data, and session traces.
3. The third step is to analyze the data collected in the second step and isolate the cause of the performance problem. This is often the most challenging part of the performance tuning exercise.
4. The fourth step is to solve the problem by creating a solution that addresses the root cause. Solutions are not always obvious and, therefore, this part of the exercise might require a great deal of ingenuity and creativity.
5. The fifth step is to implement the solution in a safe and controlled manner. An appropriate level of testing should be conducted. "Before" and "after" measurements should be obtained if possible in order to quantify the performance improvement.

No matter how simple or complex the performance problem, the steps leading to its solution are always the same. The original paper written by Chris Lawson can be downloaded from the Database Specialists website.