Triggers

This chapter provides general information about writing trigger functions. Trigger functions can be written in most of the available procedural languages, including PL/pgSQL (PL/pgSQL — SQL Procedural Language), PL/Tcl (PL/Tcl — Tcl Procedural Language), PL/Perl (PL/Perl — Perl Procedural Language), and PL/Python (PL/Python — Python Procedural Language). 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.

• Overview of Trigger Behavior
• Visibility of Data Changes
• Writing Trigger Functions in C
• A Complete Trigger Example