Question - What is the junk dimension?
Answer -
A Junk Dimension is a type of dimension table consisting of attributes that do not belong in the fact table or in any of the other existing dimension tables. The characteristics of these attributes are usually text or various flags, e.g., non-generic comments or very simple yes/no or true/false indicators. These sorts of attributes typically remain when all the apparent dimensions within the business process are identified, and thus the designer is faced with the challenge of where to place these attributes that don’t belong within the other dimensions.
In some scenarios where data might not be appropriate to store within the schema. The info or attributes are often stored during a junk dimension; the character of the junk during this particular dimension is typically Boolean or flag values. A single dimension is formed by lumping a small number of dimensions. This is called a junk dimension adjunct dimension has unrelated attributes the process of grouping these random flags and text attributes in a dimension by transmitting them to a distinguished sub-dimension is related to junk dimension, so essentially any data that need not be stored in the data warehouse because it is unnecessary is stored in the junk dimension.