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<?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>CREATE LANGUAGE</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="sql-createindex.html" title="CREATE INDEX" /><link rel="next" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE LANGUAGE</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createindex.html" title="CREATE INDEX">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATELANGUAGE"><div class="titlepage"></div><a id="id-1.9.3.70.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE LANGUAGE</span></h2><p>CREATE LANGUAGE — define a new procedural language</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <em class="replaceable"><code>name</code></em>
HANDLER <em class="replaceable"><code>call_handler</code></em> [ INLINE <em class="replaceable"><code>inline_handler</code></em> ] [ VALIDATOR <em class="replaceable"><code>valfunction</code></em> ]
CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <em class="replaceable"><code>name</code></em>
</pre></div><div class="refsect1" id="SQL-CREATELANGUAGE-DESCRIPTION"><h2>Description</h2><p>
<code class="command">CREATE LANGUAGE</code> registers a new
procedural language with a <span class="productname">PostgreSQL</span>
database. Subsequently, functions and procedures can be
defined in this new language.
</p><p>
<code class="command">CREATE LANGUAGE</code> effectively associates the
language name with handler function(s) that are responsible for executing
functions written in the language. Refer to <a class="xref" href="plhandler.html" title="Chapter 58. Writing a Procedural Language Handler">Chapter 58</a>
for more information about language handlers.
</p><p>
<code class="command">CREATE OR REPLACE LANGUAGE</code> will either create a
new language, or replace an existing definition. If the language
already exists, its parameters are updated according to the command,
but the language's ownership and permissions settings do not change,
and any existing functions written in the language are assumed to still
be valid.
</p><p>
One must have the
<span class="productname">PostgreSQL</span> superuser privilege to
register a new language or change an existing language's parameters.
However, once the language is created it is valid to assign ownership of
it to a non-superuser, who may then drop it, change its permissions,
rename it, or assign it to a new owner. (Do not, however, assign
ownership of the underlying C functions to a non-superuser; that would
create a privilege escalation path for that user.)
</p><p>
The form of <code class="command">CREATE LANGUAGE</code> that does not supply
any handler function is obsolete. For backwards compatibility with
old dump files, it is interpreted as <code class="command">CREATE EXTENSION</code>.
That will work if the language has been packaged into an extension of
the same name, which is the conventional way to set up procedural
languages.
</p></div><div class="refsect1" id="SQL-CREATELANGUAGE-PARAMETERS"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">TRUSTED</code></span></dt><dd><p><code class="literal">TRUSTED</code> specifies that the language does
not grant access to data that the user would not otherwise
have. 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><span class="term"><code class="literal">PROCEDURAL</code></span></dt><dd><p>
This is a noise word.
</p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
The name of the new procedural language.
The name must be unique among the languages in the database.
</p></dd><dt><span class="term"><code class="literal">HANDLER</code> <em class="replaceable"><code>call_handler</code></em></span></dt><dd><p><em class="replaceable"><code>call_handler</code></em> is
the name of a previously registered function that will be
called to execute the procedural language's 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
<code class="type">language_handler</code> type, a placeholder type that is
simply used to identify the function as a call handler.
</p></dd><dt><span class="term"><code class="literal">INLINE</code> <em class="replaceable"><code>inline_handler</code></em></span></dt><dd><p><em class="replaceable"><code>inline_handler</code></em> is the
name of a previously registered function that will be called
to execute an anonymous code block
(<a class="link" href="sql-do.html" title="DO"><code class="command">DO</code></a> command)
in this language.
If no <em class="replaceable"><code>inline_handler</code></em>
function is specified, the language does not support anonymous code
blocks.
The handler function must take one argument of
type <code class="type">internal</code>, which will be the <code class="command">DO</code> command's
internal representation, and it will typically return
<code class="type">void</code>. The return value of the handler is ignored.
</p></dd><dt><span class="term"><code class="literal">VALIDATOR</code> <em class="replaceable"><code>valfunction</code></em></span></dt><dd><p><em class="replaceable"><code>valfunction</code></em> 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 <code class="type">oid</code>, which will be the OID of the
to-be-created function, and will typically return <code class="type">void</code>.
</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" id="SQL-CREATELANGUAGE-NOTES"><h2>Notes</h2><p>
Use <a class="link" href="sql-droplanguage.html" title="DROP LANGUAGE"><code class="command">DROP LANGUAGE</code></a> to drop procedural languages.
</p><p>
The system catalog <code class="classname">pg_language</code> (see <a class="xref" href="catalog-pg-language.html" title="53.29. pg_language">Section 53.29</a>) records information about the
currently installed languages. Also, the <span class="application">psql</span>
command <code class="command">\dL</code> lists the installed languages.
</p><p>
To create functions in a procedural language, a user must have the
<code class="literal">USAGE</code> privilege for the language. By default,
<code class="literal">USAGE</code> is granted to <code class="literal">PUBLIC</code> (i.e., everyone)
for trusted languages. This can be revoked if desired.
</p><p>
Procedural languages are local to individual databases.
However, a language can be installed into the <code class="literal">template1</code>
database, which will cause it to be available automatically in
all subsequently-created databases.
</p></div><div class="refsect1" id="SQL-CREATELANGUAGE-EXAMPLES"><h2>Examples</h2><p>
A minimal sequence for creating a new procedural language is:
</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>
Typically that would be written in an extension's creation script,
and users would do this to install the extension:
</p><pre class="programlisting">
CREATE EXTENSION plsample;
</pre></div><div class="refsect1" id="SQL-CREATELANGUAGE-COMPAT"><h2>Compatibility</h2><p>
<code class="command">CREATE LANGUAGE</code> is a
<span class="productname">PostgreSQL</span> extension.
</p></div><div class="refsect1" id="id-1.9.3.70.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alterlanguage.html" title="ALTER LANGUAGE"><span class="refentrytitle">ALTER LANGUAGE</span></a>, <a class="xref" href="sql-createfunction.html" title="CREATE FUNCTION"><span class="refentrytitle">CREATE FUNCTION</span></a>, <a class="xref" href="sql-droplanguage.html" title="DROP LANGUAGE"><span class="refentrytitle">DROP LANGUAGE</span></a>, <a class="xref" href="sql-grant.html" title="GRANT"><span class="refentrytitle">GRANT</span></a>, <a class="xref" href="sql-revoke.html" title="REVOKE"><span class="refentrytitle">REVOKE</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-createindex.html" title="CREATE INDEX">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE INDEX </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="40%" align="right" valign="top"> CREATE MATERIALIZED VIEW</td></tr></table></div></body></html>
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