```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_start for a given metric_id and optional segment. The table contains 580 unique readings across 2 metrics (m_5ef7a17b with 24 readings, m_64a39818 with 556 readings) spanning 24 time periods. While period_start exists as a time axis, the dimension classification indicates this table serves as a reference/lookup table rather than a temporal snapshot or event log." } ] } ```