Dimensions provide the “who, what, where, when, why, and how” context surrounding a business process event. Dimension tables contain the descriptive attributes used by BI applications for ﬁltering and grouping the facts. With the grain of a fact table ﬁrmly in mind, all the possible dimensions can be identiﬁed. Whenever possible, a dimension should be single valued when associated with a given fact row.
Dimension tables are sometimes called the “soul” of the data warehouse because they contain the entry points and descriptive labels that enable the DW/BI system to be leveraged for business analysis. A disproportionate amount of effort is put into the data governance and development of dimension tables because they are the drivers of the user’s BI experience.