Dimensions overview

A dimension unifies (or conforms) similar attributes from one or various source systems into a single table under a common unique identifier known as a business key. A single surrogate key can also be used in place of multi-column business or primary keys. The unique key of a dimension table plays a critical role in identifying dimension records and allows the database team to track and maintain changes over time. A dimension table can be structured in predetermined ways to allow for different types of change tracking depending on the business requirement.

SCD types

Attributes within a dimension have differing requirements for durability and change tracking. Some attributes are updated directly, while others require historical snapshots, yet others cannot change at all. This section will cover the types of SCDs, or update profiles, that a given attribute in a dimension can have.

It’s important to note that the dimension type may not necessarily apply...