Link Hashkeys should be generated using the Business Keys participating in the Link, and not the Hashkeys of of the Hubs. Hashing a hash is just bad design.
A Satellite contains the descriptive attributes of a Business Key. As such, a Satellite HASHDIFF should be constructed using the only the descriptive attributes of the Business Key. The Business Key, itself, should not be part of the Satellite HASHDIFF. Note: While it is a common practice to include the Business Keys in the SAT … Data Vault Anti-pattern: Including Business Keys in the SAT HASHDIFF
When using a Change Data Capture (CDC) tool it is possible to get multiple records for the same Business Key in a single micro-batch. Loading this data as-is will will result in multiple records for the same Business Key for the same LOAD_DATE. This is the incorrect loading pattern. A regular Satellite should have only … Data Vault Anti-pattern: Using Multi-Active SAT to model data with multiple records for the same Business Key that arrive one Micro-batch
A Satellite, by definition, should have only one record per Business Key per Load Date. The Business Key (or the hash of the Business Key) + LOAD_DATE is the unique key for the record. BK + LOAD_DATE is the Primary of the SatelliteThe exception is a Multi-Active Satellite where a Sequence Number is added to … Data Vault Anti-pattern: Having two or more records in a SAT for a Single Business Key with the same LOAD_DATE
Dependent Children should not have their own Hubs. They are not Business Concepts and as such should not be a Business Key by themselves. They only make sense when associated with a Business concept. One example is Line Items in a Order. The Line Item in Order by itself does not make sense. It needs to … Data Vault Anti-pattern: Creating Hubs for Dependent Children