===== Structure Concepts ======


==== Dimensional model ====

A dimesional model typically contains the same information as an E/R model but packages the data differently to that of  an normal transactional system (e.g. SAP, Oracle Financials).  The data structure in a dimensional model are normally modelled to allow using three key principles:

  * Ease of user understanding
  * Query Performance
  * Ease of adaption to change without major impact

The dimensional model has a number of key components, some of which are listed below.

=== Dimensions ===

Dimensions are used to describe attributes of the main information table (also known as the fact tables).

=== Facts ===

Fact tables hold the main information in each dimensional model. The information in the fact table relates to the measurements that are useful / required by the business.  A fact is usually of one of three types:

  * Numeric
  * Addative