Types of Dimention table in DWH

We know Dimension tables contain descriptive information about a subject or matter. Here "ID" column in each dimention table is very important.
Because "Id" has used inside Fact table to express full Information of Each row in Dimention table. That is way the name of "ID" column is Primary Key Column.

There are many more types of dimention table exists in DWH.
Among them the main 5 types are:

1. Conformed Dimention
2. Degenerate Dimention
3. Junk Dimention
4. Role Playing Dimention
5. Slowly Chenging Dimention

Now we will discuss each topic one by one.

Conformed Dimention

It is dimension table that relates to multiple fact tables within the same data warehouse.
It has the same meaning to every fact with which it relates.

Example :
For HR Core (Employee management) DWH, the Employee Dimention table is a conformed dimension because it have the same meaning when joined to any fact table in a HR Core DWH.
and similar to this Dimention_Date table is also a conformed dimension (day, week, month, quarter, year, etc.) because it have the same meaning when joined to any fact table in a DWH.


Degenerate Dimention

A degenerate dimension is a attribute, which stored as part of fact table, but donot have separate dimension table.It is standalone attribute.

Example: For sales related DWH, the "Invoice Number" attribute is degenerate dimension
because there are no dimention table for that. But it plays vital role in fact table.

Junk Dimention

It is a dimension that exists in fact table and measures to answer business questions.
It is just a collection of random transnational codes, Identifiers, flags or text attributes.

Example: For sales related DWH, "Is_Food" & "Is_offer" is the Junk Dimention.