```json { "table_name": "metric_readings", "primary_key": "reading_id", "candidates": [ { "rank": 0, "partition_key": "reading_id", "partition_key_label": "primary_identifier", "partition_key_reasoning": "reading_id is the unique identifier with RPUV=1.00, uniqueness=1.000, and 0% null rate. As a dimension table, the primary identifier serves as the natural partition key for lookups and joins.", "clustering_key": null, "clustering_key_label": null, "clustering_key_reasoning": "Dimension tables typically do not require clustering keys as they are accessed by primary key lookups rather than range scans.", "world_line": null, "session_column": null, "confidence": "HIGH", "notes": "This is a dimension table storing metric reading records. Each reading_id uniquely identifies a metric measurement at a specific period for a specific segment. The table is classified as dimension with reading_id as the entity column. While period_start exists as a time axis, dimension tables are organized by their primary identifier rather than temporal ordering." } ] } ```