ITWissen.info - Tech know how online

dimension

In the context of ITWissen.info, the term dimension stands for a type of data storage. In Online Analytical Processing (OLAP) and today generally also in Business Intelligence Systems (BI), the data that embody properties are often stored as so-called dimensions. They stand in contrast to facts

, which embody key figures.The term dimension is derived from the conceptual representation of data as a multidimensional cube, also called

anOLAP c

ube.Leading the way in the development of OLAP concepts was Ralph Kimball.

OLAP

cube with different dimensions

cube with different dimensions

In an OLAP cube, the data structure consists of properties and key figures that are stored as facts. The properties are understood as attributes on an imaginary dimensional axis, analogous to

the axes of a three-dimensional cube. In contrast to the spatial model, the dimensional axes of the OLAP cube are not necessarily directed. Properties of the type 1, 2, 3, ... (directed) as well as of the type Hamburg, Cologne, Munich, ...The key figures that are evaluated are set in context with the properties. Each key figure is always assigned to a node of characteristics of all dimensions within an OLAP cube. For example, the key figure "Sales" can be assigned to the dimensional characteristics "Cologne", month "May" and product category "Non-Food". In this example, the sales for non-food products in Cologne in the month of May are therefore displayed.

Facts and dimensions can also be managed in fact and dimension tables.

The fact table contains the metrics and key figures, whereas the dimension table, which represents a dimension of an OLAP cube, contains the descriptions.

Informationen zum Artikel
Englisch: dimension
Updated at: 04.02.2014
#Words: 340
Links: