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 36.17.

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))