<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >CREATE LANGUAGE</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 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="SQL Commands" HREF="sql-commands.html"><LINK REL="PREVIOUS" TITLE="CREATE INDEX" HREF="sql-createindex.html"><LINK REL="NEXT" TITLE="CREATE OPERATOR" HREF="sql-createoperator.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="2007-02-02T03:57:22"></HEAD ><BODY CLASS="REFENTRY" ><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 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="sql-createindex.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="sql-createindex.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="sql-createoperator.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="sql-createoperator.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SQL-CREATELANGUAGE" ></A >CREATE LANGUAGE</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN39592" ></A ><H2 >Name</H2 >CREATE LANGUAGE -- define a new procedural language</DIV ><A NAME="AEN39595" ></A ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN39597" ></A ><H2 >Synopsis</H2 ><PRE CLASS="SYNOPSIS" >CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <TT CLASS="REPLACEABLE" ><I >name</I ></TT > HANDLER <TT CLASS="REPLACEABLE" ><I >call_handler</I ></TT > [ VALIDATOR <TT CLASS="REPLACEABLE" ><I >valfunction</I ></TT > ]</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="SQL-CREATELANGUAGE-DESCRIPTION" ></A ><H2 >Description</H2 ><P > Using <TT CLASS="COMMAND" >CREATE LANGUAGE</TT >, a <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > user can register a new procedural language with a <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > database. Subsequently, functions and trigger procedures can be defined in this new language. The user must have the <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > superuser privilege to register a new language. </P ><P > <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > effectively associates the language name with a call handler that is responsible for executing functions written in the language. Refer to <A HREF="xplang.html" >Chapter 34</A > for more information about language call handlers. </P ><P > Note that procedural languages are local to individual databases. To make a language available in all databases by default, it should be installed into the <TT CLASS="LITERAL" >template1</TT > database. </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="SQL-CREATELANGUAGE-PARAMETERS" ></A ><H2 >Parameters</H2 ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="LITERAL" >TRUSTED</TT ></DT ><DD ><P > <TT CLASS="LITERAL" >TRUSTED</TT > specifies that the call handler for the language is safe, that is, it does not offer an unprivileged user any functionality to bypass access restrictions. If this key word is omitted when registering the language, only users with the <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > superuser privilege can use this language to create new functions. </P ></DD ><DT ><TT CLASS="LITERAL" >PROCEDURAL</TT ></DT ><DD ><P > This is a noise word. </P ></DD ><DT ><TT CLASS="REPLACEABLE" ><I >name</I ></TT ></DT ><DD ><P > The name of the new procedural language. The language name is case insensitive. The name must be unique among the languages in the database. </P ><P > For backward compatibility, the name may be enclosed by single quotes. </P ></DD ><DT ><TT CLASS="LITERAL" >HANDLER</TT > <TT CLASS="REPLACEABLE" ><I >call_handler</I ></TT ></DT ><DD ><P > <TT CLASS="REPLACEABLE" ><I >call_handler</I ></TT > is the name of a previously registered function that will be called to execute the procedural language functions. The call handler for a procedural language must be written in a compiled language such as C with version 1 call convention and registered with <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > as a function taking no arguments and returning the <TT CLASS="TYPE" >language_handler</TT > type, a placeholder type that is simply used to identify the function as a call handler. </P ></DD ><DT ><TT CLASS="LITERAL" >VALIDATOR</TT > <TT CLASS="REPLACEABLE" ><I >valfunction</I ></TT ></DT ><DD ><P > <TT CLASS="REPLACEABLE" ><I >valfunction</I ></TT > is the name of a previously registered function that will be called when a new function in the language is created, to validate the new function. If no validator function is specified, then a new function will not be checked when it is created. The validator function must take one argument of type <TT CLASS="TYPE" >oid</TT >, which will be the OID of the to-be-created function, and will typically return <TT CLASS="TYPE" >void</TT >. </P ><P > A validator function would typically inspect the function body for syntactical correctness, but it can also look at other properties of the function, for example if the language cannot handle certain argument types. To signal an error, the validator function should use the <CODE CLASS="FUNCTION" >ereport()</CODE > function. The return value of the function is ignored. </P ></DD ></DL ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="SQL-CREATELANGUAGE-NOTES" ></A ><H2 >Notes</H2 ><P > This command normally should not be executed directly by users. For the procedural languages supplied in the <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > distribution, the <A HREF="app-createlang.html" ><SPAN CLASS="APPLICATION" >createlang</SPAN ></A > program should be used, which will also install the correct call handler. (<TT CLASS="COMMAND" >createlang</TT > will call <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > internally.) </P ><P > In <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > versions before 7.3, it was necessary to declare handler functions as returning the placeholder type <TT CLASS="TYPE" >opaque</TT >, rather than <TT CLASS="TYPE" >language_handler</TT >. To support loading of old dump files, <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > will accept a function declared as returning <TT CLASS="TYPE" >opaque</TT >, but it will issue a notice and change the function's declared return type to <TT CLASS="TYPE" >language_handler</TT >. </P ><P > Use the <A HREF="sql-createfunction.html" ><I >CREATE FUNCTION</I ></A > command to create a new function. </P ><P > Use <A HREF="sql-droplanguage.html" ><I >DROP LANGUAGE</I ></A >, or better yet the <A HREF="app-droplang.html" ><SPAN CLASS="APPLICATION" >droplang</SPAN ></A > program, to drop procedural languages. </P ><P > The system catalog <CODE CLASS="CLASSNAME" >pg_language</CODE > (see <A HREF="catalog-pg-language.html" >Section 41.18</A >) records information about the currently installed languages. Also <TT CLASS="COMMAND" >createlang</TT > has an option to list the installed languages. </P ><P > To be able to use a procedural language, a user must be granted the <TT CLASS="LITERAL" >USAGE</TT > privilege. The <TT CLASS="COMMAND" >createlang</TT > program automatically grants permissions to everyone if the language is known to be trusted. </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="SQL-CREATELANGUAGE-EXAMPLES" ></A ><H2 >Examples</H2 ><P > The following two commands executed in sequence will register a new procedural language and the associated call handler. </P><PRE CLASS="PROGRAMLISTING" >CREATE FUNCTION plsample_call_handler() RETURNS language_handler AS '$libdir/plsample' LANGUAGE C; CREATE LANGUAGE plsample HANDLER plsample_call_handler;</PRE ><P> </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="SQL-CREATELANGUAGE-COMPAT" ></A ><H2 >Compatibility</H2 ><P > <TT CLASS="COMMAND" >CREATE LANGUAGE</TT > is a <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > extension. </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN39690" ></A ><H2 >See Also</H2 ><A HREF="sql-alterlanguage.html" ><I >ALTER LANGUAGE</I ></A >, <A HREF="sql-createfunction.html" ><I >CREATE FUNCTION</I ></A >, <A HREF="sql-droplanguage.html" ><I >DROP LANGUAGE</I ></A >, <A HREF="sql-grant.html" ><I >GRANT</I ></A >, <A HREF="sql-revoke.html" ><I >REVOKE</I ></A >, <A HREF="app-createlang.html" ><I ><I >createlang</I ></I ></A >, <A HREF="app-droplang.html" ><I ><I >droplang</I ></I ></A ></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="sql-createindex.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="sql-createoperator.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >CREATE INDEX</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="sql-commands.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >CREATE OPERATOR</TD ></TR ></TABLE ></DIV ></BODY ></HTML >