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.