- **Description**: Scans an index without needing to access the table. - **Performance**: Efficient if all needed columns are in the index. - **Factors**: Index size, selectivity, CPU costs. - **Cost**: `index cost + cpu_index_tuple_cost * number of index entries` - ![[ex_index_only_scan.svg|200x200]] - **Workloads**: - [[IO]] - [[DataFileRead]] - [[LWLock]] - [[BufferContent]] - [[BufferMapping]] - **Operates on**: [[Math and Computation/Databases/Postgres/Structures/Index|Index]]