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Data model

technology Maturity 11-13 Next article →

A data model is an abstract plan used to organize information.

Data modeling context
Data modeling context

It standardizes how data elements relate to one another. It also defines how they relate to real-world entities. For example, a model for a car might specify its color and size. It might also define who the owner is. This process is known as data modeling or database design. Experts like data scientists or data librarians create these models. They often use specific languages and graphical diagrams to show the structure.

B 5 1 IDEF1X Diagram
B 5 1 IDEF1X Diagram

Data models serve two closely related purposes. Sometimes, a model refers to the formalization of objects in a specific area. This might include customers, products, and orders in a factory. At other times, the term refers to the set of concepts used to build those formalizations. These concepts include entities, attributes, relations, or tables. For instance, a banking application might use an entity-relationship model. This model helps describe the structure, manipulation, and integrity of stored data. It can even describe data with looser structures, like emails or digital videos.

Effective data modeling is vital for building information systems. The main goal is to provide a clear definition and format for data. When data structures are consistent, different applications can share information easily. However, poor quality models cause significant problems. If entity types are identified incorrectly, data might be duplicated. This leads to extra costs in development and maintenance. Furthermore, different systems often use arbitrary structures. This requires complex interfaces to connect them. These interfaces can account for 25% to 70% of the cost of current systems.

4-3 Data Modelling Today
4-3 Data Modelling Today

To manage complexity, experts often use the ANSI/SPARC three-level architecture.

4-2 ANSI-SPARC three level architecture
4-2 ANSI-SPARC three level architecture

This approach provides three distinct perspectives. The first is the conceptual data model. This describes the semantics, or the meaning, of a specific domain. It consists of entity classes and the relationships between them. The second is the logical data model. This describes how data is represented by specific technology, such as tables, columns, or XML tags. The third is the physical data model. This describes the actual physical means of storage, including things like CPUs and partitions.

This three-level approach is significant because it allows the layers to remain independent. You can change the storage technology without affecting the conceptual model. You can also change the table structure without changing the conceptual model. In software development, engineers often start with a conceptual model. They then detail it into a logical model. Finally, they translate that into a physical model for the computer to use. This layered method ensures that the system remains consistent even as technology evolves.

The history of data modeling is filled with important breakthroughs. In 1958, Young and Kent sought an abstract way to specify data problems. They wanted a notation that worked regardless of the hardware used. In 1959, the CODASYL consortium worked toward a machine-independent language. The 1960s saw the rise of management information systems. Charles Bachman designed the Integrated Data Store, the first generation of database systems. During this time, the network and hierarchical models were proposed. In 1969, Edgar F. Codd proposed the relational model based on logic. This changed how we arrange data forever.

In the 1970s, new methods emerged to handle complex information. Peter Chen formalized entity-relationship modeling in 1976. This helped designers describe information needs during the early stages of a project. This technique can describe any ontology, which is a classification of concepts and their relationships. Later, researchers like G.M. Nijssen and Terry Halpin developed Object-Role Modeling. Bill Kent, in his 1978 book, offered a famous comparison. He said a data model is like a map of a territory. A map does not show every tiny detail, like red paint on a highway. Similarly, a model creates order out of the messiness of the real world.

A2 4 Semantic Data Models
A2 4 Semantic Data Models

Modern data modeling continues to evolve through different paradigms. In the 1980s, the object-oriented paradigm changed how we view data. Traditionally, data and procedures were stored separately. Object orientation combined an entity's data with its procedures. In the 1990s, mathematicians like Guido Bakema and Harm van der Lek focused on communication. They worked on the semantics of how information is shared. In 1997, they formalized the Fully Communication Oriented Information Modeling method. These advancements ensure that data remains a powerful tool for modern technology.

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🖼️ Images & Media (10)
File:Data modeling context.svg
Data modeling context.svg
File:4-2 ANSI-SPARC three level architecture.svg
4-2 ANSI-SPARC three level architecture.svg
File:Aggregate Data Structure Diagram.jpg
Aggregate Data Structure Diagram.jpg
File:B 5 1 IDEF1X Diagram.jpg
B 5 1 IDEF1X Diagram.jpg
File:A2 4 Semantic Data Models.svg
A2 4 Semantic Data Models.svg
File:4-3 Data Modelling Today.svg
4-3 Data Modelling Today.svg
File:3-2 Properties of data.svg
3-2 Properties of data.svg
File:Binary tree.svg
Binary tree.svg
File:A 01 Audio compact disc collection.svg
A 01 Audio compact disc collection.svg
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JKDOM.SVG
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