Submitted by wolf on Jan 26, 2021

Description

Dimensional modeling (DM) is part of the Business Dimensional Lifecycle methodology developed by Ralph Kimball which includes a set of methods, techniques and concepts for use in data warehouse design. The approach focuses on identifying the key business processes within a business and modelling and implementing these first before adding additional business processes, a bottom-up approach.

The business process model consists of different object types that link together using primary key that is meaningless and has not business content.

  • Dimension - A dimension is a satellite entity that captures attribute information about a data class and typically contains slowly changing values. Attributes that are fast changing or measure observations should not be stored in a dimension and should be stored in a Fact. Some dimension capture history of attribute changes and some do not. Dimension can can be Type 0 - 7.
  • Junk Dimension - These minimize the number of Foreign Keys (FK) in a Fact table and separate reusable and non-additive information from the Fact table.
  • Fact - The hold the relationships between Dimension tables and business information at a particular point in time. The information stored in the fact table is specific to the measures associated with the class of events. The business drives the definition of the Fact table.
  • Fact-less Fact - These manage the relationships between Dimensions, at a specific point in time, but do not contain any measures.
  • Bridge - A Bridge table connects two objects and resolves a many-to-may relationship. A Bridge table is not a Dimension nor is it a Fact table. It can have Type-1 or Type-2 tendencies.

Helpful Links

Type 1 Dimension example

Type 2 Dimension example

Fact Table example

Fact-less Fact Table

Bridge Table

Use Case Example

Click this Link to open a document detailing the steps needed to create a Type 1 Dimension.

Click this Link to open a document detailing the steps needed to create a Type 2 Dimension.

Click this Link to open a document detailing the steps needed to create a Fact Table. {TW will update this link}