A Logical Data Model has 3 components
Facts: Facts are measures, which exists as columns in fact tables. Facts can be from different fact tables, and can from different source systems
Attributes : Attributes are descriptive data. Without attributes, facts are meaningless. They provide context for analysing the fact data. Attributes can exists in dimensions tables, lookup , relationship and fact tables.
Attributes forms(Attribute forms are microstrategy specific concepts) are different individual properties that forms a single attribute. Eg : Employee ID, Emp SSN , EmpName are attribute forms for Employee attribute. In Logical data models, attribute forms are usually not included.
Attribute elements are values of an attribute. Eg: 2001,2002 etc are attribute elements for year attribute.
Attribute relationship is the logical association between the attributes based on business rules.
Direct – a Parent child relationship using lookup table or distinct relation table
Indirect – related only through a fact. Eg relation between customer and date attributes are through the sales fact
Direct relationship can be on-to-one relation or one-to-many relation or many-to-many relation
Hierarchies : Hierarchies are grouping of directly related attributes ordered to reflect their relationship. Hierarchies are grouped based on logical business areas. All the hierarchies we include in the logical data model forms the system hierarchy and user hierarchy may not need to follow the logical data model.