![[str_idx_brin.png|256]] - **Description**: "Block Range INdex". Instead of indexing every row, it stores a tiny summary (like min/max values) for each range of blocks (typically 1MB). - **Supported Operators**: `<`, `<=`, `=`, `>=`, `>`. - **Special Features**: - Extremely small footprint (can be 1000x smaller than B-Tree). - Only effective if the data is physically ordered on disk (e.g., a `timestamp` column in an append-only log). - **Metaphor**: Summary labels on a long row of massive warehouse boxes. You don't open the box to see every widget; the label just says "Widgets 100-200 are in here."