```json { "table_name": "beer_upcs", "primary_key": "upc,beer_id", "candidates": [ { "rank": 0, "partition_key": "beer_id", "partition_key_label": "primary_identifier", "partition_key_reasoning": "beer_id is the natural primary identifier for this dimension table. RPUV=1.20 indicates most beers have 1-2 UPC codes, which is reasonable for product variants. Uniqueness=0.810 and Top 3 Coverage=0.05% shows good distribution. Semantically, this table maps UPCs to beers, making beer_id the organizing entity.", "clustering_key": null, "clustering_key_label": null, "clustering_key_reasoning": "No clustering needed for dimension table. The few UPCs per beer_id don't require internal ordering.", "world_line": null, "session_column": null, "confidence": "HIGH", "notes": "This is a many-to-one mapping table (UPC → beer). The composite key (upc, beer_id) ensures uniqueness, but beer_id is the natural partition key as queries will typically look up all UPCs for a given beer. The 2.9% null rate in beer_id represents unmapped UPCs. user_id appears to be a contributor/editor field and is not suitable as a key (high RPUV=22.64, 3.57% nulls, top value dominates 3.4% of rows)." } ] } ```