This chapter provides general information about writing trigger functions. Trigger functions can be written in most of the available procedural languages, including PL/pgSQL ( Chapter 40 ), PL/Tcl ( Chapter 41 ), PL/Perl ( Chapter 42 ), and PL/Python ( Chapter 43 ). After reading this chapter, you should consult the chapter for your favorite procedural language to find out the language-specific details of writing a trigger in it.
It is also possible to write a trigger function in C, although most people find it easier to use one of the procedural languages. It is not currently possible to write a trigger function in the plain SQL function language.