Rapidly Changing Dimension is also known as Fast Changing Dimension. We usually implement the Slowly Changing Dimension using type 2 to keep history. However, it would be an issue to implement a rapidly changing dimension using type 2. Type 2 implementation would be a disaster to grow the dimension table rapidly (dimension becomes huge number of rows). Instead, we use type 4 to manage rapidly changing dimension.
We identify, separate and split the frequently changing attributes from master dimension into one or more mini-dimension. We usually further reclass their values by band ranges to reduce the values combination (number of rows) in the mini-dimension. Both the master dimension and mini-dimension will be associated with the fact table separately. In this approach, we keep the change history and greatly reduce the size of dimension tables. As a drawback, we can't simply list the change history by effective date fields from a dimension table alone.
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| Figure: Rapidly Changing Dimension |
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