CREATE EXTENSION

CREATE EXTENSION

7

SQL - Language Statements

CREATE EXTENSION

install an extension

CREATE EXTENSION \[ IF NOT EXISTS \]

extension\_name

\[ WITH \] \[ SCHEMA

schema\_name

\] \[ VERSION

version

\] \[ CASCADE \]

Description
===========

`CREATE EXTENSION` loads a new extension into the current database.
There must not be an extension of the same name already loaded.

Loading an extension essentially amounts to running the extension\'s
script file. The script will typically create new SQL objects such as
functions, data types, operators and index support methods.
`CREATE EXTENSION` additionally records the identities of all the
created objects, so that they can be dropped again if `DROP EXTENSION`
is issued.

The user who runs `CREATE EXTENSION` becomes the owner of the extension
for purposes of later privilege checks, and normally also becomes the
owner of any objects created by the extension\'s script.

Loading an extension ordinarily requires the same privileges that would
be required to create its component objects. For many extensions this
means superuser privileges are needed. However, if the extension is
marked trusted in its control file, then it can be installed by any user
who has `CREATE` privilege on the current database. In this case the
extension object itself will be owned by the calling user, but the
contained objects will be owned by the bootstrap superuser (unless the
extension\'s script explicitly assigns them to the calling user). This
configuration gives the calling user the right to drop the extension,
but not to modify individual objects within it.

Parameters
==========

`IF NOT EXISTS`

:   Do not throw an error if an extension with the same name already
    exists. A notice is issued in this case. Note that there is no
    guarantee that the existing extension is anything like the one that
    would have been created from the currently-available script file.

extension\_name

:   The name of the extension to be installed. PostgreSQL will create
    the extension using details from the file
    `SHAREDIR/extension/`extension\_name`.control`.

schema\_name

:   The name of the schema in which to install the extension\'s objects,
    given that the extension allows its contents to be relocated. The
    named schema must already exist. If not specified, and the
    extension\'s control file does not specify a schema either, the
    current default object creation schema is used.

    If the extension specifies a `schema` parameter in its control file,
    then that schema cannot be overridden with a `SCHEMA` clause.
    Normally, an error will be raised if a `SCHEMA` clause is given and
    it conflicts with the extension\'s `schema` parameter. However, if
    the `CASCADE` clause is also given, then schema\_name is ignored
    when it conflicts. The given schema\_name will be used for
    installation of any needed extensions that do not specify `schema`
    in their control files.

    Remember that the extension itself is not considered to be within
    any schema: extensions have unqualified names that must be unique
    database-wide. But objects belonging to the extension can be within
    schemas.

version

:   The version of the extension to install. This can be written as
    either an identifier or a string literal. The default version is
    whatever is specified in the extension\'s control file.

`CASCADE`

:   Automatically install any extensions that this extension depends on
    that are not already installed. Their dependencies are likewise
    automatically installed, recursively. The `SCHEMA` clause, if given,
    applies to all extensions that get installed this way. Other options
    of the statement are not applied to automatically-installed
    extensions; in particular, their default versions are always
    selected.

Notes
=====

Before you can use `CREATE EXTENSION` to load an extension into a
database, the extension\'s supporting files must be installed.
Information about installing the extensions supplied with PostgreSQL can
be found in [Additional Supplied Modules](#contrib).

The extensions currently available for loading can be identified from
the [pg\_available\_extensions](#view-pg-available-extensions) or
[pg\_available\_extension\_versions](#view-pg-available-extension-versions)
system views.

> **Caution**
>
> Installing an extension as superuser requires trusting that the
> extension\'s author wrote the extension installation script in a
> secure fashion. It is not terribly difficult for a malicious user to
> create trojan-horse objects that will compromise later execution of a
> carelessly-written extension script, allowing that user to acquire
> superuser privileges. However, trojan-horse objects are only hazardous
> if they are in the `search_path` during script execution, meaning that
> they are in the extension\'s installation target schema or in the
> schema of some extension it depends on. Therefore, a good rule of
> thumb when dealing with extensions whose scripts have not been
> carefully vetted is to install them only into schemas for which CREATE
> privilege has not been and will not be granted to any untrusted users.
> Likewise for any extensions they depend on.
>
> The extensions supplied with PostgreSQL are believed to be secure
> against installation-time attacks of this sort, except for a few that
> depend on other extensions. As stated in the documentation for those
> extensions, they should be installed into secure schemas, or installed
> into the same schemas as the extensions they depend on, or both.

For information about writing new extensions, see
[???](#extend-extensions).

Examples
========

Install the [hstore](#hstore) extension into the current database,
placing its objects in schema `addons`:

    CREATE EXTENSION hstore SCHEMA addons;

Another way to accomplish the same thing:

    SET search_path = addons;
    CREATE EXTENSION hstore;

Compatibility
=============

`CREATE EXTENSION` is a PostgreSQL extension.

See Also
========
