A relational database management system ( RDBMS ) is a database management system (DBMS) based on the relational model found by Edgar F. Codd at IBM's San Jose Research Laboratory. Most widely used databases today are based on their relational database model.
RDBMS has become a common choice for storing information in databases used for financial, manufacturing and logistics information, personnel data, and other applications since the 1980s. Relational databases often replace legacy hierarchical databases and network databases because they are easier to implement and manage. Nevertheless, relational databases received steadily, challenges that were unsuccessful by object database management systems in the 1980s and 1990s, (which were introduced in an attempt to address the so-called object-relational impedance mismatch between relational databases and object-oriented application programs) , as well as by the XML database management system in the 1990s. However, due to a stretch of technology, such as the horizontal scale of computer clusters, the recent NoSQL database is beginning to break the RDBMS market share.
Video Relational database management system
According to DB-Engines, in May 2017, the most widely used systems are Oracle, MySQL (free software), Microsoft SQL Server, PostgreSQL (free software), IBM DB2, Microsoft Access, and SQLite (free software).
According to research firm Gartner, in 2011, five leading relational database software vendors based on revenue were Oracle (48.8%), IBM (20.2%), Microsoft (17.0%), SAP including Sybase (4.6 %), and Teradata (3.7%).
Maps Relational database management system
History
In 1974, IBM began to develop System R, a research project to develop the RDBMS prototype. However, the first commercial RDBMS available was Oracle, released in 1979 by Relational Software, now Oracle Corporation. Other examples of RDBMS include DB2, SAP Sybase ASE, and Informix. In 1984, the first RDBMS for the Macintosh began to be developed, code-named Silver Surfer, was later released in 1987 as the 4th Dimension and is known today as 4D.
Historical use of the term
The term "relational database" was invented by E. F. Codd at IBM in 1970. Codd introduced this term in his research paper "The Relational Data Model for Large Joint Data Banks". In this paper and later papers, he defines what is meant by "relational". One well-known definition of what constitutes a relational database system consists of 12 Codd rules. However, many of the early implementations of relational models do not fit all Codd rules, so this term has gradually come to describe a broader class of database systems, which at least:
- Show the data to the user as a relation (presentation in table form, ie as a collection table with each table consisting of a set of rows and columns);
- Provides relational operators to manipulate data in tabular form.
The first relatively faithful implementation of the relational model comes from:
- University of Michigan - Micro DBMS (1969)
- Massachusetts Institute of Technology (1971)
- IBM UK Scientific Center at Peterlee - IS1 (1970-72) and its successor, PRTV (1973-79)
The first system sold as RDBMS was Multics Relational Data Store (1978). Ingres and IBM BS12 follow.
The most common RDBMS definition is a product that presents the view of data as a collection of rows and columns, though not based on relational theory. By this definition, the RDBMS product usually implements some but not all 12 Codd rules.
A second group of thought holds that if the database does not apply all of Codd's rules (or the current understanding of the relational model, as Christopher J Date, Hugh Darwen and others say), it is not relational. This view, shared by many theorists and other strict adherents to Codd's principles, would disqualify most of the DBMS as being irrational. For clarification, they often refer to some of the RDBMS as a truly relational database management system (TRDBMS), naming others pseudo-relational database management systems (PRDBMS).
As of 2009, most commercial relational DBMSs use SQL as their query language.
Alternative query languages ​​have been proposed and implemented, especially the pre-1996 implementation of Ingres QUEL.
See also
- SQL
- Database object (OODBMS)
- Online analytical processing (OLAP) and ROLAP (Relational Online Analytics Processing)
- Data warehouse Star scheme
- Snowflake Scheme
References
Source of the article : Wikipedia
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