Slowly Changing Dimensions Type 4
Usually, we use SCD-type-4 when a dimension(SCD Type 2) grows rapidly due to the frequently changing of its attributes. These frequently changing attributes will be removed from the main dimension and added in to a new one known as Mini-Dimension.

==> Mini Dimension do not store the historical attributes, but the fact table preserved the history of dimension attribute assignment

A good example is illustrated here : link-SCD4