Data Modeling

A data model in software engineering is an abstract model that try to represent the reality and describes how data are represented and accessed. Data models formally define data elements and relationships among data elements for a domain of interest.

Data modeling is the foundation of most database-centered transaction processing systems and data warehouse systems.

There are two basic types of physical models :

• Data Modeling - Entity-Relationship (E-R) (E-R) and

E-R models are designed to minimize data storage redundancy and optimize data updates.

• Dimensional Modeling - Dimensional Schemas

Dimensional models are designed to enhance understandability and to optimize query performance.

• Data Vault

The Data Vault consists of three primary entity types:

• Hubs,
• Links,
• and Satellites.

The Hubs are core business keys, the Links form all relationships, and the Satellites provide all descriptive information.

• Dimensional Modeling - Dimensional Schemas
  • Data Warehousing - Snowflake schema
  • Data Warehousing - Star Schema

Complex schemas rarely scale well.

• Dimensional Modeling - Fact Table
  • Dimensional Modeling - Degenerate Dimension of Fact dimension (i.e. event/header entity)
  • Dimensional Modeling - Measures / Facts
• Dimensional Modeling - Dimension
  • Dimensional Modeling - Hierarchy
  • Dimensional Modeling - Level
  • Data Modeling - Attribute
• Dimensional Modeling - Cube (Olap Cube)

The terms dimension and fact come from a joint research conducted by General Mills and Darmouth Univeristy in the 1960s.

• Data Modeling - Entity (Object, Table) and Instance (Row)
• Data Modeling - Attribute
• Data Modeling - Key (Identifier)
• Data Modeling - Relationships
• Data Modeling - Normalization
• Data Modeling - Denormalization
  • Data Modeling - Denormalization Methods (Changing the Database Design to Reduce the Number of Joins)
• Data Modeling - Referential Integrity
• Data Modeling - Cardinality
• Data Modeling - Degree
• Data Modeling - Data dictionary
• Data Modeling - Metadata

Data modeling is a sort of ontology.

Ontology is the philosophical study of the nature of being, existence or reality in general which deals with questions concerning what entities exist or can be said to exist, and how such entities can be grouped, related within a hierarchy, and subdivided according to similarities and differences.

• Power Architect
• Oracle Sql Developer Data Modeler
• CA ERwin Data Modeler
• Sybase PowerDesigner
• IBM Rational Data Architect
• Embarcadero ER/Studio
• Quest Toad Data Modeler
• Microsoft Visio

• Data_model