Latest News

Monday, December 11, 2017

Types of Dimensions in data warehouse

What is a Dimension Table: 
 A table which consists of the attributes about the facts is called a Dimension Table.
Dimensions store the textual descriptions of the business. It helps to measure the facts.

The different types of dimension tables:

  1. Conformed Dimension: It mean the exact Dimension Table liked with every possible fact table to which they are joined.  Eg: The date dimension table connected to the sales facts is identical to the date dimension connected to the inventory facts.
  2. Junk Dimension: A junk dimension is a collection of random transactional codes flags and/or text attributes that are unrelated to any particular dimension. The junk dimension is simply a structure that provides a convenient place to store the junk attributes. Eg: Assume that we have a gender dimension and marital status dimension. In the fact table we need to maintain two keys referring to these dimensions. Instead of that create a junk dimension which has all the combinations of gender and marital status (cross join gender and marital status table and create a junk table). Now we can maintain only one key in the fact table.
  3. Degenerated Dimension: A degenerate dimension is a dimension which is derived from the fact table and doesn't have its own dimension table.  Eg: A transactional code in a fact table.
  4. Role-playing dimension: Dimensions which are often used for multiple purposes within the same database are called role-playing dimensions. For example, a date dimension can be used for “date of sale", as well as "date of delivery", or "date of hire"
  • Google+
  • Pinterest

No comments

Post a Comment