```json { "table_name": "neal_reading_groups", "primary_key": "reading_id,rank", "candidates": [ { "rank": 0, "partition_key": "reading_id", "partition_key_label": "primary_identifier", "partition_key_reasoning": "RPUV=3.67 indicates ~4 rows per reading_id (rank 1-4 breakdown). Top 3 coverage 5.45% is well-distributed. Semantically, reading_id is the primary entity being decomposed into ranked groups/categories.", "clustering_key": "rank", "clustering_key_label": null, "clustering_key_reasoning": "Rank orders the breakdown rows (1-4) within each reading_id. Monotonicity 0.731 confirms natural ordering. This is a structural ordering column for the dimension breakdown, not a temporal axis.", "world_line": null, "session_column": null, "confidence": "HIGH", "notes": "This is a dimension table storing ranked breakdowns (top-N groups) for each reading_id. Each reading has 3-4 ranked entries (label/value pairs) plus a remainder row. The composite key (reading_id, rank) uniquely identifies each breakdown row. Clustering by rank ensures the top groups appear first within each reading's partition." } ] } ```