Functions
A PostgreSQL function is used to provide a distinct service, and is often composed of a set of declarations, expressions, and statements. PostgreSQL has very rich built-in functions for almost all the existing data types. In this chapter, we will focus on user-defined functions. However, details about the syntax and function parameters will be covered in the following chapters.
PostgreSQL native programming languages
PostgreSQL supports out-of-the-box user-defined functions to be written in C, SQL and PL/pgSQL. There are also three other procedural languages that come with the standard PostgreSQL distribution: PL/Tcl, PL/Python, and PL/Perl. However, one needs to create the language in order to use them via the CREATE EXTENSION PostgreSQL command or via the createlang utility tool.
The simplest way to create a language and make it accessible to all the databases is to create it in template1, directly after the PostgreSQL cluster installation. Note that one does not need to perform...
