Andyblg's Blog

September 22, 2009

Database and cube dimensions

Filed under: OLAP — andyblg @ 11:42
Tags: ,

Very interesting note from Microsoft (Sql Server BOL or Designing Dimensions):

“… A database dimension is a collection of related objects, called attributes, which can be used to provide information about fact data in one or more cubes. For example, typical attributes in a product dimension might be product name, product category, product line, product size, and product price. These objects are bound to one or more columns in one or more tables in a data source view. By default, these attributes are visible as attribute hierarchies and can be used to understand the fact data in a cube. Attributes can be organized into user-defined hierarchies that provide navigational paths to assist users when browsing the data in a cube.

Cubes contain all the dimensions on which users base their analyses of fact data. An instance of a database dimension in a cube is called a cube dimension and relates to one or more measure groups in the cube. A database dimension can be used multiple times in a cube. For example, a fact table can have multiple time-related facts, and a separate cube dimension can be defined to assist in analyzing each time-related fact. However, only one time-related database dimension needs to exist, which also means that only one time-related relational database table needs to exist to support multiple cube dimensions based on time…”

Thus:
– during designing DW we define database dimensions (concept of dw level)
– during designing Cube we have deal with cube dimensions (concept of cube level)

hm…

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