We have discussed the use of junk dimensions in data modelling and in this post we are going to explore Degenerate dimension. Lets start with the definition.
A high cardinality attribute column in the fact table which does not have any other content except its natural key and is required as a dimension for analysis or drill-down purpose, is called a degenerate dimension. As this degenerate dimension is constructed from a fact table item and is placed in the fact table, it is also known as fact dimension. It helps to reduce duplicate data by placing high cardinality dimension key in the fact table.
Degenerate dimension keys are significantly unique and are nearly as large as fact table. Moving this attribute in a single column dimension table requires a considerably large dimension table, and you would also need to join the surrogate key of the fact … More