Dimension 
Dimension
Definition
The grouping of classification groups (characteristics) that logically belong together as regards content, under one generic term. If the dimension contains a characteristic whose value already uniquely determines the values of all other characteristics from a business-orientated viewpoint, then the dimension is named after this characteristic.
The customer dimension could, for example, be made up of the customer number, the customer group and the levels of the customer hierarchy.
The sales dimension could contain the characteristics ‘sales person’, ‘sales group’ and ‘sales office’.
The time dimension could be given using the characteristics ‘day’ (in the form YYYYMMDD), ‘week’ (in the form YYYY.WW), ‘month’ (in the form YYYY.MM), ‘year’ (in the form YYYY) and ‘period’ (in the form YYYY.PPP).
Use
Definition in the Star Schema
When defining an InfoCube, characteristics for dimensions are grouped together to store them in a table of the star schema (dimension table). The afore-mentioned business-orientated grouping can be the basis for this. With the aid of a simple foreign key dependency, dimensions are linked to one of the key fields of the fact table.
Structure
From a technical viewpoint, several characteristic values are mapped to an abstract dimension key (DIM ID), to which the values in the fact table refer. The characteristics chosen for an InfoCube are divided up among InfoCube-specific dimensions when creating the InfoCube.