PostgreSQL is a robust open-source object-relational database management system (ORDBMS) which is based on Postgres version 4.2. It is an open source software/project which means that everyone has the permission to use, modify, improve and redistribute PostgreSQL and nobody has to pay for it.
Some of its features are :-
1. Object-Relational DBMS - Database is simply a collection of data which is stored in a computer. PostgreSQL approaches data stored in the database with an object-relational model.
2. PostgreSQL includes SQL support - It supports the core SQL99 specification and also includes some of the SQL92 standards.
3. Supports internal procedural languages.
4. PostgreSQL has a flexible API.
5. PostgreSQL supports data types, functions, index methods and operators which are user-defined.
Advantages of PostgreSQL are :-
1. Incorporation of various procedural languages.
2. Highly compliant with SQL standards.
3. Nice Java Database Connectivity(JDBC) and PHP support.
Disadvantages of PostgreSQL :-
1. Slower than MySQL.
2. Does not supports entire SQL92 standards.
3. Less open source applications support than MySQL.