V. Server Programming
This part is about extending the server functionality with
user-defined functions, data types, triggers, etc. These are
advanced topics which should probably be approached only after all
the other user documentation about PostgreSQL has
been understood. This part also describes the server-side
programming languages available in the
PostgreSQL distribution as well as
general issues concerning server-side programming languages. This
information is only useful to readers that have read at least the
first few chapters of this part.