Insights that Jonathan provides into the workings of cost-based optimizer will make a DBA a better designer, and developer of a better SQL programmer. With this information at your fingertips, you will save a large amount of time designing and troubleshooting your SQL. The cost-based optimizer is only a piece of code that contains a model of how Oracle databases work. By applying this model to the statistics about your data, the optimizer tries to efficiently convert your query into the execution plan. Unfortunately, these models can not be perfect, your statistics can not be perfect, and the resulting execution plan may be far from perfect. In Cost-Based Oracle Fundamentals, the first book in the series of three, Jonathan Lewis, one of the leading authorities in this field, explains the most common use of the model, what the optimizer to do with your stats, and why things go wrong.