Glossary
Natural Key
A natural key (or business key) is an identifier that already exists in the business domain: an account number, SKU, email address, or national ID. It arrives with the data, means something to users, and is how source systems refer to the entity.
Natural keys remain essential in the warehouse — they’re how you match incoming records to existing dimension rows — but they make poor primary keys for dimensions: they get recycled, reformatted, and duplicated across systems, and they can’t represent history. Standard practice keeps the natural key as an attribute for lookups and joins to source data, while a generated surrogate key serves as the actual primary key.