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The Dimensional Fact Model (DFM)〔 is an ad hoc and graphical formalism specifically devised to support the conceptual modeling phase in a DW project. 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. Data Warehouses (DWs) are databases used by decision makers to analyze the status and the development of an organization. DWs are based on large amounts of data integrated from heterogeneous sources into multidimensional databases, and they are optimized for accessing data in a way that comes naturally to human analysts (e.g., OLAP applications). Data in a DW are organized according to the multidimensional model, that hinges on the concepts of fact (a focus of interest for the decision-making process, such as sales and orders) and dimension (a coordinate for analyzing a fact, such as time, customer, and product). Each fact is quantified through a set of numerical measures, such as the quantity of product sold, the price of products, etc. DW design and development require ad hoc methodologies and an appropriate life-cycle.〔Matteo Golfarelli and Stefano Rizzi. (''Data Warehouse Design - Modern Principles and Methodologies'' ). McGrawHill, 2009.〕〔Ralph Kimball, et al. (''The Data Warehouse Lifecycle Toolkit'' ). Wiley, 2008.〕〔Oscar Romero, Alberto Abelló. "A Survey of Multidimensional Modeling Methodologies". In ''Int. Journal on Data Warehousing and Mining'' (IJDWM), volume 5, number 2. Idea Group 2009. Pages 1-23. ISSN: 1548-3924〕 == Overview == The DFM is a graphical conceptual model, specifically devised for multidimensional design, in order 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 * build a stable platform for logical design * provide clear and expressive design documentation. The conceptual representation generated by the DFM consists of a set of fact schemata. Fact schemata model facts, measures, dimensions, and hierarchies (see Figure 1). Besides these basic elements, the DFM includes a large set of constructs for expressing the multitude of conceptual nuances that characterize actual modeling scenarios in projects of small to large complexity. A multidimensional schema modeled with the DFM can easily (i.e., semi-automatically) be implemented on both ROLAP and MOLAP platforms. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dimensional Fact Model」の詳細全文を読む スポンサード リンク
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