- "Bushy" and shallow.
- Index can be sparse or dense.
- Record are stored in key order.
Operations
- Scan: Scan the leaf layer, where the records are.
- Equality search: Search index, landing on page containing record.
- Range search: Search index for lo, landing on page containingn first record
of interest. Scan forward until hi is reached.
- Insert: Search index, update page, add index entry.
- Update: Search index, update page.
- Delete: Search index, update page, delete index entry.