One-pass size is when the size of the work area is below optimal size and an extra pass is performed over part of the input data. This is the ideal size for the work area. Optimal size is when the size of a work area is large enough that it can accommodate the input data and auxiliary memory structures allocated by its associated SQL operator. Generally, bigger work areas can significantly improve the performance of a particular operator at the cost of higher memory consumption. Oracle Database enables you to control and tune the sizes of work areas.
