Oracle Internal Arch. (contd.)
- Bit-map index : There is a bit-vector for each key. One bit is stored for each row.
- index based on computed values (e.g. salary + bonus); can be constructed without storing result (available only to cost-based optimizer ).
- index-organized tables : can be constructed on one or more fields. Data is stored in B* tree itself. No extra storage is required for key and pointer (ROWID). In fact, no ROWIDs are assigned. This is efficient when large number of accesses specify this key. Additional indexes using the key as logical key are also possible.