Columns: Data identifiers and values

Columns are fields in the warehouse that contain attribute and fact data. The types of columns are:

ID columns contain attribute element identification codes. These codes are typically numeric because computers can process numbers much more rapidly than text. All attributes must have an ID column.
Description columns contain descriptions (text or numeric) of attribute elements. Description columns are optional.
An ID column can serve a dual purpose as both an ID and description. Date is one example of an attribute that usually does not have a description column.
The majority of attributes typically have an ID column and at least one description column. If an attribute has many attribute forms—additional descriptive information about a given attribute—they are represented by additional description columns.