What is a Junk Dimension in SQL Server Analysis Services? In what scenarios do you use it?

A Junk Dimension is often a collection of Unrelated Attributes like indicators, flags, codes, etc. This Dimension usually contains data which cannot be created as a separate Dimension as they tend to be too small (often) and are not worth having a separate Dimension.

These Dimensions can be used in various scenarios, but one of the common scenarios is when a Fact Table contains a lot of Attributes which are like indicators, flags, etc. Using Junk Dimensions, such Attributes can be removed/cleaned up from a Fact Table.

Example:- 

It contains values like Yes/No, Pending/In Progress/Completed, Open/Resolved/Closed, etc.

Here are some highlights of a Junk Dimension:It is also called as a Garbage Dimension.

Junk Dimensions are usually small in size.

It is a convenient way to consolidate many Smaller Dimensions which are not really worth having as a separate Dimension.