-SAT is a Link Satellite
, which is connected to the Link
primary key, just as a Hub
-SAT) is connected to a Hub
This is a valid entity in Data Vault
and contains attributes which describe the relationship.
The discussion about validity that I know of is about using attributes within (Transactional) Link
tables, but I never heard about the fact a Link Satellite
would be inappropriate in general.
For example you could have a relationship between a product and a store where it is sold.
would be L_Product_Store.
If you like to store contextual data about this relationship you need to create a satellite
related to the link
. Some attributes specific for this relationship, and therefore stored in the LINK
-SAT could be :
- stock on hand
- local article
- assortment start date
- assortment expiry date
Another example could be, Employee and Function.
Given the link
L_Employee_Function contains all relationships that ever have existed between those 2 entities, there must be a place that can tell when the Function assignment was valid.
This due to the fact that Function assignments within a company can change over time.
That would be the link satellite
, containing the Assignment_Start_Date and Assignment_End_Date attributes for example.
I hope this helps,