The Dimensional Fact Model

The Dimensional Fact Model is an ad hoc and graphical formalism specifically devised to support the conceptual modeling phase in a Data Warehouse project. The Dimensional Fact Model, or DFM,  is extremely intuitive and can be used by analysts and non-technical users as well. A short-term working is sufficient to realize a clear and exhaustive representation of multidimensional concepts (e.g., attributes, measures and hierarchies). It can be used from the initial DW life-cycle steps, to rapidly devise a conceptual model to share with customers. To this purpose, indyco Builder represents the first tool to further accelerate the design of the conceptual model by using DFM, while indyco Explorer is its counterpart that can be used by any business user to understand the Data Mode. 

The goals of the Dimensional Fact Model are to:
– lend effective support to conceptual design;
– create an environment in which user queries may be formulated intuitively;
– make communication possible between designers and end users with the goal of formalizing requirement specifications;
– enable early testing and verification of user requirements;
– build a stable platform for logical design;
– provide clear and expressive design documentation.

(figure) A fact is represented by a box that displays the fact name along with the measure names. Small circles represent the dimensions, which are linked to the fact by straight lines.

A fact is a concept relevant to decision-making processes. It typically models a set of events taking place within a company. Examples of facts in the commercial domain are sales, shipments, purchases, and complaints.

A measure is a numerical property of a fact and describes a quantitative attribute that is relevant to analysis. For example, each sale is measured by the number of units sold, the unit price, and the total receipts.

A dimension is a property, with a finite domain, that describes an analysis coordinate of the fact. A fact generally has multiple dimensions that define its minimum representation granularity. Typical dimensions for the sales fact are products, stores, and dates; in which case, the basic information that can be represented is product sales in one store in one day.

A dimensional attribute is a property, with a finite domain, of a dimension. Like dimensions, a dimensional attribute is represented by a circle. For instance, a product may be described by its type, category, and brand; a customer may be represented by city and nation. The relationships among the dimensional attributes are expressed by hierarchies.

A hierarchy is a directed tree whose nodes are dimensional attributes and whose arcs model many-to-one associations between dimensional attribute pairs. A hierarchy includes a dimension, positioned at the tree’s root, and all of the dimensional attributes that describe it. Arcs are graphically represented by straight lines that connect dimensional attributes. Hierarchies define the way elemental business events can be selected and aggregated for decision-making processes.

What is indyco? Drawing on an innovative graphical representation of requirements, indyco enables the co-creation of an enterprise data warehouse, automatically validated by the Dimensional Fact Model.