The principle of orthogonal design (abbreviated POOD) was developed by database researchers David McGoveran and Christopher J. Date in the early 1990s, and first published "A New Database Design Principle" in the July 1994 issue of Database Programming and Design and reprinted several times. It is the second of the two principles of database design, which seek to prevent databases from being too complicated or redundant, the first principle being the principle of full normalization (POFN).
David McGoveran is an American computer scientist and physicist, software industry analyst, and inventor. In computer science, he is recognized as one of the pioneers of relational database theory. In the field of physics, his most notable work is in discrete and bit-string physics, in which he derived fundamental dimensionless constants from first principles.
Chris Date is an independent author, lecturer, researcher, and consultant, specializing in relational database theory.
Database design is the organisation of data according to a database model. The designer determines what data must be stored and how the data elements interrelate. With this information, they can begin to fit the data to the database model.
Simply put, it says that no two relations in a relational database should be defined in such a way that they can represent the same facts. As with database normalization, POOD serves to eliminate uncontrolled storage redundancy and expressive ambiguity, especially useful for applying updates to virtual relations (e.g., view (database)). Although simple in concept, POOD is frequently misunderstood and the formal expression of POOD continues to be refined.
A relational database is a digital database based on the relational model of data, as proposed by E. F. Codd in 1970. A software system used to maintain relational databases is a relational database management system (RDBMS). Virtually all relational database systems use SQL for querying and maintaining the database.
Database normalization is the process of structuring a relational database in accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It was first proposed by Edgar F. Codd as an integral part of his relational model.
The principle is a restatement of the requirement that a database is a minimum cover set of the relational algebra. The relational algebra allows data duplication in the relations that are the elements of the algebra. One of the efficiency requirements of a database is that there be no data duplication. This requirement is met by the minimum cover set of the relational algebra.
Sources
Database Debunkings: The Principle of Orthogonal Design, Part I, by D. McGoveran and C. J. Date
Database Debunkings: The Principle of Orthogonal Design, Part II, by D. McGoveran and C. J. Date
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
Related Research Articles
The relational model (RM) for database management is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.
A data model is an abstract model that organizes elements of data and standardizes how they relate to one another and to properties of the real world entities. For instance, a data model may specify that the data element representing a car be composed of a number of other elements which, in turn, represent the color and size of the car and define its owner.
Fabian Pascal is a consultant to large software vendors such as IBM, Oracle Corporation, and Borland, but is better known as an author and seminar speaker. Born in Romania, Pascal lives in the San Francisco, CA area of the US, and works in association with Christopher J. Date.
Edgar Frank "Ted" Codd was an English computer scientist who, while working for IBM, invented the relational model for database management, the theoretical basis for relational databases and relational database management systems. He made other valuable contributions to computer science, but the relational model, a very influential general theory of data management, remains his most mentioned, analyzed and celebrated achievement.
Relational algebra, first created by Edgar F. Codd while at IBM, is a family of algebras with a well-founded semantics used for modelling the data stored in relational databases, and defining queries on it.
First normal form (1NF) is a property of a relation in a relational database. A relation is in first normal form if and only if the domain of each attribute contains only atomic (indivisible) values, and the value of each attribute contains only a single value from that domain. The first definition of the term, in a 1971 conference paper by Edgar Codd, defined a relation to be in first normal form when none of its domains have any sets as elements.
Second normal form (2NF) is a normal form used in database normalization. 2NF was originally defined by E.F. Codd in 1971.
Third normal form (3NF) is a normal form that is used in normalizing a database design to reduce the duplication of data and ensure referential integrity by ensuring that:
In relational databases, relvar is a term introduced by C. J. Date and Hugh Darwen as an abbreviation for relation variable in their 1995 paper The Third Manifesto, to avoid the confusion sometimes arising from the use of the term relation, by the inventor of the relational model, E. F. Codd, for a variable to which a relation is assigned as well as for the relation itself. The term is used in Date's well-known database textbook An Introduction to Database Systems and in various other books authored or coauthored by him.
The object-relational impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management system (RDBMS) is being served by an application program written in an object-oriented programming language or style, particularly because objects or class definitions must be mapped to database tables defined by a relational schema.
D is a set of prescriptions for what Christopher J. Date and Hugh Darwen believe a relational database management system ought to be like. It is proposed in their paper The Third Manifesto, first published in 1994 and elaborated on in several books since then.
Boyce–Codd normal form is a normal form used in database normalization. It is a slightly stronger version of the third normal form (3NF). BCNF was developed in 1975 by Raymond F. Boyce and Edgar F. Codd to address certain types of anomalies not dealt with by 3NF as originally defined.
Sixth normal form (6NF) is a term in relational database theory, used in two different ways.
Relational Model/Tasmania (RM/T) was published by Edgar F. Codd in 1979 and is the name given to a number of extensions to his original relational model (RM) published in 1970. The overall goal of the RM/T was to define some fundamental semantic units, at "atomic" and "molecular" levels, for data modelling. Codd writes: "the result is a model with a richer variety of objects than the original relational model, additional insert-update-delete rules and some additional operators that make the algebra more powerful."
In relational database theory, a relation, as originally defined by E. F. Codd, is a set of tuples (d1, d2, ..., dn), where each element dj is a member of Dj, a data domain. Codd's original definition notwithstanding, and contrary to the usual definition in mathematics, there is no ordering to the elements of the tuples of a relation. Instead, each element is termed an attribute value. An attribute is a name paired with a domain. An attribute value is an attribute name paired with an element of that attribute's domain, and a tuple is a set of attribute values in which no two distinct elements have the same name. Thus, in some accounts, a tuple is described as a function, mapping names to values.
An Imieliński-Lipski algebras is an extension of relational algebra onto tables with different types of null values. It is used to operate on relations with incomplete information.
