workarea_size_policy specifies the memory allocation policy for SQL working areas. workarea_size_policy can be set to: auto | Lets Oracle allocate memory for the working areas. Oracle considers the value of pga_aggregate_target when workarea_size_policy is set to auto. |
manual | The size of the working area is based on the *_area_size values (sort_area_size, hash_area_size, bitmap_merge_area_size and create_bitmap_area_size). |
auto (which is set if the value of pga_aggregate_target is nonzero) workarea_size_policy to manual can lead to «sub-optimal performance and poor PGA memory utilization».