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 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 later chapters.

PostgreSQL native programming language

PostgreSQL supports out-of-the-box user-defined functions 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 languages in order to use it, 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 databases is to create it in template1, directly after the PostgreSQL cluster installation. Note that one does not need to perform this step for C, SQL...