Entity

Entities represent business or technical information that is in the atomic repository or data warehouse.

The entities that are provided in the Atomic Warehouse Model (AWM) are the basic building blocks for the information repository that is developed.

Transformation patterns

The physical structure of the fundamental entities is obtained by applying transformation rules, which are driven by the data load, workload, and attributes affinity.

Data load: Data load describes the dynamics of data volumes associated with a data structure, such as the initial number of occurrences, the growth rate, and the deletion rate.
Workload: Workload describes the expected level of access activity associated with the data structure, such as query frequency. If a join operation is expected to be frequently performed on the same two entities, for example, merging the entities into a single table at physical level can significantly enhance performance.

The following transformations can occur:

Rolling up: The fundamental entity is rolled up into its supertype.
Rolling down: The fundamental entity is rolled down into its subtype.
Separate entity: The fundamental entity remains a separate fundamental entity.

The following entity types are used in modeling data in the warehouse:

Fundamental entities represent logical data structures that hold atomic business information.
Associative entities represent logical data structures that hold information related to the association between two fundamental entities.
History entities track the history of an entity instance by defining a subset of the entity attributes whose values are valid for a given duration.
Supportive entities represent common codes, enumeration values, and technical information that is used by other entity types.

Entities are color-coded on the basis of their subject area when shown in subject area diagrams.

All entities in AWM share common properties that are visible when modeling in a combination of diagrams, navigation, or property views.

Name - indicates the purpose of the entity to the modeler and uniquely identifies the entity
Description - explains the purpose of the entity and often includes examples
Package - the name of the parent package of the entity in the model
Attributes - the list of business and technical attributes that make up the entity
Attribute Groups - the list of attribute groups that are defined on the entity
Primary Key - the attribute or attributes that uniquely identify instances of the entity
Relationships - show how entities are related to each other with the use of foreign keys
Model Mappings - show how an entity is mapped to an entity in other data models

Fundamental entity
An Atomic Warehouse Model (AWM) fundamental entity represents a logical data structure that holds a group of atomic business information. A fundamental entity supports one or more business terms and is designed to achieve the objectives of AWM. A fundamental entity is derived from the business terms by applying ER modeling techniques. fundamental entities are organized in a type hierarchy, which classifies them from the more abstract down to the most specific and helps to define common properties.
Associative entity
An Atomic Warehouse Model (AWM) associative entity represents a logical data structure that holds the information related to the association between two fundamental entities. An AWM associative entity supports one or more business terms and is designed to achieve the objectives of AWM. An associative entity is derived from the business terms by applying ER modeling techniques. An associative entity only holds the current values of the association. Associative entities allow the grouping together of associations that have the same left and right parent, avoiding changes when new types of association are defined.
Supportive entity
A supportive entity is used to support the data warehouse and does not always originate directly from business terms. It is usually created to support technical information or enumeration values that can be assigned to various entities. Enumeration values include values, such as code values, for example gender, or type values such as event type. A supportive entity can also be used to handle code values and their translations.
History entity
A history entity tracks the history of an entity instance, by defining a subset of the entity attributes, whose values are valid during a given time. Unlike an associative entity, which stores history of data values that relate to a relationship between two entity instances, a history entity supports the history management of an entity instance in its own right, rather than in its relationship with other entity instances.

Parent topic: Atomic Warehouse Model elements