Troubleshooting Query Transformations
Stelios Charalambides · Apress eBooks · 2013
The Oracle query optimizer is an amazing piece of code, developed and improved over the years (with perhaps a few blind alleys along the way) to generate execution plans that are both easy to generate and that run fast. The optimizer uses a number of “tricks” along the way to improve the speed of execution and implements the execution plan in a way that gives the same results as your unmodified SQL. These “tricks” (or heuristics) sometimes include query transformations.