In Turbocharge Your Warehouse, Dan Lindstedt says:

 

“A Hub must have at least 1 business key

A Hub should not contain a composite set of business keys. ** exception below”

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A Hub Business Key MAY also be composite because the key is utilized as a composite key within the business

Hub’s business key must stand-alone in the environment: either be a system created key, or a true business key that is the single basis for “finding” information in the source system.

A True business key is often referred to as a NATURAL KEY

Linstedt, Dan (2012-05-20). Super Charge Your Data Warehouse: Invaluable Data Modeling Rules to Implement Your Data Vault (Data Warehouse Architecture Book 1) ”

 

ODE caters for One or more Business Keys, held in discrete columns.

This means that, when joining to a Hub, a query can use either part of the key without having to interpret a concatenated column.

Keys could be concatenated in the Business Rules phase of any load and passed to ODE as a unique key.

However, this may restrict the generation of Data Heritage information in future releases of ODE.