Data engineering·Modelling for analysis
the dimension row has a meaningless integer id of your own invention, which is why the source renumbering its customers did not break anything.
Surrogate key
Also calledwarehouse key, synthetic key
A key generated by the warehouse, carrying no business meaning, used to join facts to dimensions. It insulates you from the source changing its identifiers, it lets one logical entity have several rows over time, and it is short, which matters when it is repeated across a billion fact rows. It is the enabling trick for type-2 history: without it, there is no way for a fact to point at the version of the customer that existed when the fact occurred.