NAME

       CREATE_EXTENSION - install an extension

SYNOPSIS

       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.

       The extensions currently available for loading can be identified from the pg_available_extensions or
       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 Section 38.17.

EXAMPLES

       Install the 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

       ALTER EXTENSION (ALTER_EXTENSION(7)), DROP EXTENSION (DROP_EXTENSION(7))