PostgreSQL is very rich in built-in data types and external extensions. It can be easily extended using the C and C++ languages. In fact, PostgreSQL provides an extension-building infrastructure, called PGXS, so that extensions can be built against an installed server. Some PostgreSQL extensions, such as PostGIS, require complete chapters of their own so that they can be discussed.
PostgreSQL provides a very rich set of data types, such as XML, hstore, JSON, and array. These data types can be used to ease the developer's life by not reinventing the wheel and utilizing their very rich set of functions and operators. Also, several PostgreSQL data types, such as hstore and JSON, can increase the developer's agility because the database's physical design isn't often amended.
PostgreSQL arrays are very mature; they have a rich set of operators and functions...