```json { "classifications": [ { "column": "id", "label": "primary_key", "confidence": 1.0, "reason": "100% distinct (10/10), zero nulls, BIGINT type typical for primary keys" }, { "column": "dataset_id", "label": "foreign_key", "confidence": 0.95, "reason": "References dataset table; 3 distinct values across 10 rows shows repetition typical of foreign keys" }, { "column": "component", "label": "none", "confidence": 0.9, "reason": "Categorical attribute with 4 distinct values; describes component type, not a key" }, { "column": "reason", "label": "none", "confidence": 1.0, "reason": "Descriptive text field with only 2 distinct values; clearly an attribute, not a key" }, { "column": "flagged_at", "label": "none", "confidence": 0.95, "reason": "Timestamp field; 100% distinct but represents event time, not an identifier" } ] } ```