PostgreSQL is one of the most flexible databases available—for many reasons. On one hand, PostgreSQL can be used for many purposes. On the other hand, PostgreSQL can easily be extended and provides many programming interfaces, which are designed to extend the core features of PostgreSQL.
In this section, you take a closer look at extensibility. As you have already learned, PostgreSQL is one of the most flexible and most extensible database systems available.
Defining new database aggregate functions or operators is an easy task in PostgreSQL. This section is dedicated to all programmers who need additional functionalities, and to those who just want to have a good time hacking PostgreSQL code.