跟踪紧密地遵循实际执行路径；对于每个连接，都有一个连接准备对象、一个连接优化对象和一个连接执行对象。查询转换（IN 到 EXISTS，外连接到内连接，等等）、简化（消除子句）以及等值传播都显示在子对象中。调用范围优化器、成本评估、选择某个访问路径而非另一个的原因，或选择某种排序方法而非另一种的方法也会显示出来。A trace follows the actual execution path very closely; for each join, there is a join preparation object, a join optimization object, and a join execution object. Query transformations (IN to EXISTS, outer join to inner join, and so on), simplifications (elimination of clauses), and equality propagation are shown in subobjects. Calls to the range optimizer, cost evaluations, reasons why an access path is chosen over another one, or why a sorting method is chosen over another one, are shown as well.