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PostgreSQL (/ ˌ p oʊ s t ɡ r ɛ s k j u ˈ ɛ l / POHST-gres-kew-EL) [12] [13] also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance.
Features. Legend. User Interface: Browser based - executes on a computer server and is accessed via a network using a web browser. desktop - executes on a personal computer. Create/alter table: Yes - can create table, alter its definition and data, and add new rows.
PostgreSQL and some other databases have support for foreign schemas, which is the ability to import schemas from other servers as defined in ISO/IEC 9075-9 (published as part of SQL:2008). This appears like any other schema in the database according to the SQL specification while accessing data stored either in a different database or a ...
An entity–attribute–value model (EAV) is a data model optimized for the space-efficient storage of sparse—or ad-hoc —property or data values, intended for situations where runtime usage patterns are arbitrary, subject to user variation, or otherwise unforeseeable using a fixed design. The use-case targets applications which offer a ...
A schema migration is performed on a database whenever it is necessary to update or revert that database's schema to some newer or older version. Migrations are performed programmatically by using a schema migration tool. When invoked with a specified desired schema version, the tool automates the successive application or reversal of an ...
A federated database system (FDBS) is a type of meta- database management system (DBMS), which transparently maps multiple autonomous database systems into a single federated database. The constituent databases are interconnected via a computer network and may be geographically decentralized. Since the constituent database systems remain ...
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database. [citation needed] These integrity constraints ensure compatibility between parts of the schema. All constraints are expressible in the same language. A database can be considered a structure in realization of the ...