Identify the Logical Dimension Tables

Dimension tables contain attributes that describe business entities such as Customer Name, Region, Address and Country.

A business uses facts to measure performance by established dimensions such as by time, product, and market. Every dimension has a set of descriptive attributes. Dimension tables contain primary keys that identify each member.

Dimension table attributes provide context to numeric data, for example, by providing the ability to categorize Service Requests. Attributes stored in a service requests dimension table could include Service Request Owner, Area, Account, and Priority.

Dimensions in the business model are conformed dimensions. For example, if a specific data source has five different instances of a specific Customer table, the business model should only have one Customer table. To achieve conformance, all five physical source instances of Customer are mapped to a single Customer logical table, with transformations in the logical table source as necessary. Conformed dimensions hide the complexity of the physical layer from users, and enable combining data from multiple fact sources at different grains. Conformed dimensions enable combining multiple data sources.

The business model uses business keys for a dimension and level keys instead of generated surrogate keys. For example, you would use Customer Name with values like Oracle instead of Customer Key with values like 1076823. Using business keys in the business model ensures that all sources for that dimension can conform to the same logical dimension table with the same logical key and level key.

Generated surrogate keys can exist in the physical layer where the keys are useful for their query performance advantages on joins. The logical layer doesn't have surrogate key columns.