<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Installing Procedural Languages</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.4.8 Documentation" HREF="index.html"><LINK REL="UP" TITLE="Procedural Languages" HREF="xplang.html"><LINK REL="PREVIOUS" TITLE="Procedural Languages" HREF="xplang.html"><LINK REL="NEXT" TITLE="PL/pgSQL - SQL Procedural Language" HREF="plpgsql.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2011-04-15T03:27:09"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.4.8 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="xplang.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="xplang.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 37. Procedural Languages</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="xplang.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="plpgsql.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="XPLANG-INSTALL" >37.1. Installing Procedural Languages</A ></H1 ><P > A procedural language must be <SPAN CLASS="QUOTE" >"installed"</SPAN > into each database where it is to be used. But procedural languages installed in the database <TT CLASS="LITERAL" >template1</TT > are automatically available in all subsequently created databases, since their entries in <TT CLASS="LITERAL" >template1</TT > will be copied by <TT CLASS="COMMAND" >CREATE DATABASE</TT >. So the database administrator can decide which languages are available in which databases and can make some languages available by default if he chooses. </P ><P > For the languages supplied with the standard distribution, it is only necessary to execute <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > <TT CLASS="REPLACEABLE" ><I >language_name</I ></TT > to install the language into the current database. Alternatively, the program <A HREF="app-createlang.html" ><SPAN CLASS="APPLICATION" >createlang</SPAN ></A > can be used to do this from the shell command line. For example, to install the language <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN > into the database <TT CLASS="LITERAL" >template1</TT >, use: </P><PRE CLASS="PROGRAMLISTING" >createlang plpgsql template1</PRE ><P> The manual procedure described below is only recommended for installing custom languages that <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > does not know about. </P ><DIV CLASS="PROCEDURE" ><P ><B > Manual Procedural Language Installation </B ></P ><P > A procedural language is installed in a database in four steps, which must be carried out by a database superuser. (For languages known to <TT CLASS="COMMAND" >CREATE LANGUAGE</TT >, the second and third steps can be omitted, because they will be carried out automatically if needed.) </P ><OL TYPE="1" ><LI CLASS="STEP" ><A NAME="XPLANG-INSTALL-CR1" ></A ><P > The shared object for the language handler must be compiled and installed into an appropriate library directory. This works in the same way as building and installing modules with regular user-defined C functions does; see <A HREF="xfunc-c.html#DFUNC" >Section 34.9.6</A >. Often, the language handler will depend on an external library that provides the actual programming language engine; if so, that must be installed as well. </P ></LI ><LI CLASS="STEP" ><A NAME="XPLANG-INSTALL-CR2" ></A ><P > The handler must be declared with the command </P><PRE CLASS="SYNOPSIS" >CREATE FUNCTION <TT CLASS="REPLACEABLE" ><I >handler_function_name</I ></TT >() RETURNS language_handler AS '<TT CLASS="REPLACEABLE" ><I >path-to-shared-object</I ></TT >' LANGUAGE C;</PRE ><P> The special return type of <TT CLASS="TYPE" >language_handler</TT > tells the database system that this function does not return one of the defined <ACRONYM CLASS="ACRONYM" >SQL</ACRONYM > data types and is not directly usable in <ACRONYM CLASS="ACRONYM" >SQL</ACRONYM > statements. </P ></LI ><LI CLASS="STEP" ><A NAME="XPLANG-INSTALL-CR3" ></A ><P > Optionally, the language handler can provide a <SPAN CLASS="QUOTE" >"validator"</SPAN > function that checks a function definition for correctness without actually executing it. The validator function is called by <TT CLASS="COMMAND" >CREATE FUNCTION</TT > if it exists. If a validator function is provided by the handler, declare it with a command like </P><PRE CLASS="SYNOPSIS" >CREATE FUNCTION <TT CLASS="REPLACEABLE" ><I >validator_function_name</I ></TT >(oid) RETURNS void AS '<TT CLASS="REPLACEABLE" ><I >path-to-shared-object</I ></TT >' LANGUAGE C;</PRE ><P> </P ></LI ><LI CLASS="STEP" ><A NAME="XPLANG-INSTALL-CR4" ></A ><P > The PL must be declared with the command </P><PRE CLASS="SYNOPSIS" >CREATE [<SPAN CLASS="OPTIONAL" >TRUSTED</SPAN >] [<SPAN CLASS="OPTIONAL" >PROCEDURAL</SPAN >] LANGUAGE <TT CLASS="REPLACEABLE" ><I >language-name</I ></TT > HANDLER <TT CLASS="REPLACEABLE" ><I >handler_function_name</I ></TT > [<SPAN CLASS="OPTIONAL" >VALIDATOR <TT CLASS="REPLACEABLE" ><I >validator_function_name</I ></TT ></SPAN >] ;</PRE ><P> The optional key word <TT CLASS="LITERAL" >TRUSTED</TT > specifies that ordinary database users that have no superuser privileges should be allowed to use this language to create functions and trigger procedures. Since PL functions are executed inside the database server, the <TT CLASS="LITERAL" >TRUSTED</TT > flag should only be given for languages that do not allow access to database server internals or the file system. The languages <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN >, <SPAN CLASS="APPLICATION" >PL/Tcl</SPAN >, and <SPAN CLASS="APPLICATION" >PL/Perl</SPAN > are considered trusted; the languages <SPAN CLASS="APPLICATION" >PL/TclU</SPAN >, <SPAN CLASS="APPLICATION" >PL/PerlU</SPAN >, and <SPAN CLASS="APPLICATION" >PL/PythonU</SPAN > are designed to provide unlimited functionality and should <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >not</I ></SPAN > be marked trusted. </P ></LI ></OL ></DIV ><P > <A HREF="xplang-install.html#XPLANG-INSTALL-EXAMPLE" >Example 37-1</A > shows how the manual installation procedure would work with the language <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN >. </P ><DIV CLASS="EXAMPLE" ><A NAME="XPLANG-INSTALL-EXAMPLE" ></A ><P ><B >Example 37-1. Manual Installation of <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN ></B ></P ><P > The following command tells the database server where to find the shared object for the <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN > language's call handler function. </P><PRE CLASS="PROGRAMLISTING" >CREATE FUNCTION plpgsql_call_handler() RETURNS language_handler AS '$libdir/plpgsql' LANGUAGE C;</PRE ><P> </P ><P > <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN > has a validator function, so we declare that too: </P><PRE CLASS="PROGRAMLISTING" >CREATE FUNCTION plpgsql_validator(oid) RETURNS void AS '$libdir/plpgsql' LANGUAGE C;</PRE ><P> </P ><P > The command: </P><PRE CLASS="PROGRAMLISTING" >CREATE TRUSTED PROCEDURAL LANGUAGE plpgsql HANDLER plpgsql_call_handler VALIDATOR plpgsql_validator;</PRE ><P> then defines that the previously declared functions should be invoked for functions and trigger procedures where the language attribute is <TT CLASS="LITERAL" >plpgsql</TT >. </P ></DIV ><P > In a default <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > installation, the handler for the <SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN > language is built and installed into the <SPAN CLASS="QUOTE" >"library"</SPAN > directory. If <SPAN CLASS="APPLICATION" >Tcl</SPAN > support is configured in, the handlers for <SPAN CLASS="APPLICATION" >PL/Tcl</SPAN > and <SPAN CLASS="APPLICATION" >PL/TclU</SPAN > are also built and installed in the same location. Likewise, the <SPAN CLASS="APPLICATION" >PL/Perl</SPAN > and <SPAN CLASS="APPLICATION" >PL/PerlU</SPAN > handlers are built and installed if Perl support is configured, and the <SPAN CLASS="APPLICATION" >PL/PythonU</SPAN > handler is installed if Python support is configured. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="xplang.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="plpgsql.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Procedural Languages</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="xplang.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><SPAN CLASS="APPLICATION" >PL/pgSQL</SPAN > - <ACRONYM CLASS="ACRONYM" >SQL</ACRONYM > Procedural Language</TD ></TR ></TABLE ></DIV ></BODY ></HTML >