A Techno Blog, mainly about Java

OLAP Sandwich

I am learning about OLAP cubes… [concepts] [more]

Cubes are logical, multidimensional models that consist of the following elements:

  • One or more dimensions
  • One or more levels
  • One or more hierarchies
  • Members

Dimension – collection of closely related hierarchies that group data into natural categories (i.e. variables)

Level – level of detail within dimension

Dimensions have top level

Hierarchy – order of levels in a dimension based on parent child relationships

Member – individual value within level

 Star Schema – The set of tables includes a single fact table and one or more dimension tables. ” It is called a star schema because the diagram resembles a star, with points radiating from a center. The center of the star consists of fact table and the points of the star are the dimension tables.”

Fact Table – ” The fact tables contain fields for the individual facts as well as foreign key fields relating the facts to the dimension tables.”

Aggregate Tables – “are special fact tables in a data warehouse that contain new metrics derived from one or more aggregate functions (AVERAGE, COUNT, MIN, MAX, etc..) or from other specialized functions that output totals derived from a grouping of the base data.”

June 7, 2012 - Posted by | Uncategorized

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