woensdag 27 oktober 2010

SSAS: Dimension, hierarchies, levels, members, children, parents, etc

Currently i'm studying for my MCITP SQL BI developer 2008 certification and i thought i should dive into the mystics of MDX and at first glance the terminology sounds fuzzy: dimensions, members, hierarchies, levels, children, descendents, etc. So what are those terms?

A dimension is a familiar term: this is information about an object. A dimension could have multiple hierarchies and hierarchies consists of different levels. Hierarchies can have members and levels can have members. Members have children, children have parents....Okay... Let's try visualize this. The diagram below is my interpretation of the different terminology of MDX.

  • Hierarchy : Dimensions are defined as structural attributes of a cube made up of levels arranged in hierarchies.
  • Member : Members are the occurences of a dimension
  • Level : A level is a set of members of a dimension organized such that all members of the set are at an equal distance from the root of the hierarchy
  • First child/last child :
  • Children : On level down in the hierarchy
  • Parent: The member next level up in the hierarchy.
  • Grandparent : Two levels up in the hierarchy (2x .parent)
  • Great grand parent : Three levels up in the hierarchy (3x .parent)
  • Ancestor : Same as the parent.
So these are some explanations about some MDX terminology.


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