{{primary sources, date=March 2014
The principle of orthogonal design (abbreviated POOD) was developed by database researchers
David McGoveran
David McGoveran (born 1952) 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.
Education
David McGoveran majored ...
and
Christopher J. Date
Chris Date (born 1941) is an independent author, lecturer, researcher, and consultant, specializing in relational database theory.
Biography
Chris Date attended High Wycombe Royal Grammar School (U.K.) from 1951 to 1958 and received his BA i ...
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
Database design is the organization 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.Teorey, ...
, which seek to prevent databases from being too complicated or redundant, the first principle being the principle of full normalization ( POFN).
Simply put, it says that no two relations in a
relational database
A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relatio ...
should be defined in such a way that they can represent the same facts. As with
database normalization
Database normalization or database normalisation (see spelling differences) 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. ...
, POOD serves to eliminate uncontrolled storage redundancy and expressive ambiguity, especially useful for applying updates to virtual relations (e.g.,
view (database)
In a database, a view is the result set of a ''stored'' query on the data, which the database users can query just as they would in a persistent database collection object. This pre-established query command is kept in the database dictionary. Unl ...
). Although simple in concept, POOD is frequently misunderstood and the formal expression of POOD continues to be refined.
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. Dat * Database Debunkings: The Principle of Orthogonal Design, Part II, by D. McGoveran and C. J. Dat Database theory