What is a natural key?

< 1 min read

A natural key is a unique identifier that comes from the source business system.
It has real business meaning, like customer_email, product_code, or employee_number.
For example, order_number from the ERP uniquely identifies an order.
Unlike surrogate keys, it is not generated by the data warehouse.
We use it during data loading to detect new vs existing records.
But natural keys can change over time, like customer email updates.
That’s why we usually keep it as an attribute in dimension tables.
Fact tables normally link using surrogate keys instead.
So natural key helps identification, but not reliable for long-term relationships.

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