The Bitmap Scan icon indicates that the entire bitmap will be scanned and all of the entries that represent selected rows will be processed. Scanning a bitmap can provide large amounts of savings for the table data associated with the temporary bitmap. Since the data structure of the temporary bitmap mirrors the row number layout of the table data, the bitmap can be used to efficiently schedule paging of the table for all of the selected rows.
Also referred to as: Bitmap Scan, Preload; Row Number Bitmap Scan; Row Number Bitmap Scan, Preload