Provided by: postgresql-client-8.0_8.0.7-2build1_i386
CREATE LANGUAGE - define a new procedural language
CREATE [ TRUSTED ] [ PROCEDURAL ] LANGUAGE name
HANDLER call_handler [ VALIDATOR valfunction ]
Using CREATE LANGUAGE, a PostgreSQL user can register a new procedural
language with a PostgreSQL database. Subsequently, functions and
trigger procedures can be defined in this new language. The user must
have the PostgreSQL superuser privilege to register a new language.
CREATE LANGUAGE effectively associates the language name with a call
handler that is responsible for executing functions written in the
language. Refer to the documentation for more information about
language call handlers.
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 template1 database.
TRUSTED 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
PostgreSQL superuser privilege can use this language to create
This is a noise word.
name The name of the new procedural language. The language name is
case insensitive. The name must be unique among the languages in
For backward compatibility, the name may be enclosed by single
call_handler 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 PostgreSQL as a function taking
no arguments and returning the language_handler type, a
placeholder type that is simply used to identify the function as
a call handler.
valfunction 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
oid, which will be the OID of the to-be-created function, and
will typically return void.
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 ereport() function. The return value of
the function is ignored.
This command normally should not be executed directly by users. For
the procedural languages supplied in the PostgreSQL distribution, the
createlang(1) program should be used, which will also install the
correct call handler. (createlang will call CREATE LANGUAGE
In PostgreSQL versions before 7.3, it was necessary to declare handler
functions as returning the placeholder type opaque, rather than
language_handler. To support loading of old dump files, CREATE
LANGUAGE will accept a function declared as returning opaque, but it
will issue a notice and change the function’s declared return type to
Use the CREATE FUNCTION [create_function(7)] command to create a new
Use DROP LANGUAGE [drop_language(7)], or better yet the droplang(1)
program, to drop procedural languages.
The system catalog pg_language (see the documentation) records
information about the currently installed languages. Also createlang
has an option to list the installed languages.
To be able to use a procedural language, a user must be granted the
USAGE privilege. The createlang program automatically grants
permissions to everyone if the language is known to be trusted.
The following two commands executed in sequence will register a new
procedural language and the associated call handler.
CREATE FUNCTION plsample_call_handler() RETURNS language_handler
CREATE LANGUAGE plsample
CREATE LANGUAGE is a PostgreSQL extension.
ALTER LANGUAGE [alter_language(7)], CREATE FUNCTION
[create_function(l)], DROP LANGUAGE [drop_language(l)], GRANT
[grant(l)], REVOKE [revoke(l)], createlang [createlang(1)], droplang