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Bitemporal data in Data Vault
An excellent read on Bitemporal Data: tedamoh.com/en/konferenzen/181-flashback-to-the-data-vault-user-group-in-may-22
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Data Vault Anti-pattern: Using a HASHKEY to generate the LINK HASHKEY
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.
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Data Vault Anti-pattern: Including Business Keys in the SAT HASHDIFF
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
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Data Vault Anti-pattern: Adding column to the middle of the hashdiff
All new columns added to the SAT must be added to the end of the Satellite HASHDIFF. Dan Linstedt describes this as, “Columns that are NULL and at the end of the table are not added to the input of the hash function”[1]. Basically this pattern prevents reloading of the entire dataset when there is … Data Vault Anti-pattern: Adding column to the middle of the hashdiff
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Data Vault Anti-pattern: Using Multi-Active SAT to model data with multiple records for the same Business Key that arrive one Micro-batch
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
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Data Vault Anti-pattern: Having two or more records in a SAT for a Single Business Key with the same LOAD_DATE
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