1. What Is PostgreSQL?
PostgreSQL is an object-relational database management system ( ORDBMS ) based on POSTGRES, Version 4.2 , developed at the University of California at Berkeley Computer Science Department. POSTGRES pioneered many concepts that only became available in some commercial database systems much later.
PostgreSQL is an open-source descendant of this original Berkeley code. It supports a large part of the SQL standard and offers many modern features:
- complex queries
- foreign keys
- triggers
- updatable views
- transactional integrity
- multiversion concurrency control
Also, PostgreSQL can be extended by the user in many ways, for example by adding new
- data types
- functions
- operators
- aggregate functions
- index methods
- procedural languages
And because of the liberal license, PostgreSQL can be used, modified, and distributed by anyone free of charge for any purpose, be it private, commercial, or academic.