<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 42. Procedural Languages</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="rules-triggers.html" title="41.7. Rules Versus Triggers" /><link rel="next" href="xplang-install.html" title="42.1. Installing Procedural Languages" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 42. Procedural Languages</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="rules-triggers.html" title="41.7. Rules Versus Triggers">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="server-programming.html" title="Part V. Server Programming">Up</a></td><th width="60%" align="center">Part V. Server Programming</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="xplang-install.html" title="42.1. Installing Procedural Languages">Next</a></td></tr></table><hr></hr></div><div class="chapter" id="XPLANG"><div class="titlepage"><div><div><h2 class="title">Chapter 42. Procedural Languages</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="xplang-install.html">42.1. Installing Procedural Languages</a></span></dt></dl></div><a id="id-1.8.7.2" class="indexterm"></a><p> <span class="productname">PostgreSQL</span> allows user-defined functions to be written in other languages besides SQL and C. These other languages are generically called <em class="firstterm">procedural languages</em> (<acronym class="acronym">PL</acronym>s). For a function written in a procedural language, the database server has no built-in knowledge about how to interpret the function's source text. Instead, the task is passed to a special handler that knows the details of the language. The handler could either do all the work of parsing, syntax analysis, execution, etc. itself, or it could serve as <span class="quote">“<span class="quote">glue</span>”</span> between <span class="productname">PostgreSQL</span> and an existing implementation of a programming language. The handler itself is a C language function compiled into a shared object and loaded on demand, just like any other C function. </p><p> There are currently four procedural languages available in the standard <span class="productname">PostgreSQL</span> distribution: <span class="application">PL/pgSQL</span> (<a class="xref" href="plpgsql.html" title="Chapter 43. PL/pgSQL - SQL Procedural Language">Chapter 43</a>), <span class="application">PL/Tcl</span> (<a class="xref" href="pltcl.html" title="Chapter 44. PL/Tcl - Tcl Procedural Language">Chapter 44</a>), <span class="application">PL/Perl</span> (<a class="xref" href="plperl.html" title="Chapter 45. PL/Perl - Perl Procedural Language">Chapter 45</a>), and <span class="application">PL/Python</span> (<a class="xref" href="plpython.html" title="Chapter 46. PL/Python - Python Procedural Language">Chapter 46</a>). There are additional procedural languages available that are not included in the core distribution. <a class="xref" href="external-projects.html" title="Appendix H. External Projects">Appendix H</a> has information about finding them. In addition other languages can be defined by users; the basics of developing a new procedural language are covered in <a class="xref" href="plhandler.html" title="Chapter 56. Writing A Procedural Language Handler">Chapter 56</a>. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="rules-triggers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="server-programming.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="xplang-install.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">41.7. Rules Versus Triggers </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 42.1. Installing Procedural Languages</td></tr></table></div></body></html>
