Registers an extension in a Greenplum database.
CREATE EXTENSION [ IF NOT EXISTS ] <extension_name>
[ WITH ] [ SCHEMA <schema_name> ]
[ VERSION <version> ]
[ FROM <old_version> ]
[ CASCADE ]
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 script file. The script typically creates new SQL objects such as functions, data types, operators, and index support methods. CREATE EXTENSION
additionally records the identities of all of the created objects, so that they can be dropped again if DROP EXTENSION
is issued.
Loading an extension requires the same privileges that would be required to create its component objects. For most extensions this means superuser or database owner privileges are required. The user who runs CREATE EXTENSION
becomes the owner of the extension for purposes of later privilege checks, as well as the owner of any objects created by the extension script.
SHAREDIR/extension/<extension_name>.control
.
SHAREDIR
is the installation shared-data directory, for example
/usr/local/greenplum-db/share/postgresql
. The command
pg_config --sharedir
displays the directory.
SCHEMA
clause. Normally, an error is 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 is used for installation of any needed extensions that do not a specify schema in their control files.
FROM old_version
only if you are attempting to install an extension that replaces an
old-style module that is a collection of objects that is not packaged into an extension. This option causes
CREATE EXTENSION
to run an alternative installation script that absorbs the existing objects into the extension, instead of creating new objects. Ensure that
SCHEMA
specifies the schema containing these pre-existing objects.
SCHEMA
clause is specified, the schema applies to the extension and all dependent extensions that are installed. Other options that are specified are not applied to the automatically-installed dependent extensions; in particular, their default versions are always selected.
Before you can use CREATE EXTENSION
to load an extension into a database, the extension's supporting files must be installed. The supporting files must be installed in the same location on all Greenplum Database hosts. For information about creating new extensions, see the PostgreSQL Packaging Related Objects into an Extension documentation.
The extensions currently available for loading can be identified from the pg_available_extensions or pg_available_extension_versions system views.
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 Greenplum Database 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.
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;
CREATE EXTENSION
is a Greenplum Database extension.
ALTER EXTENSION, DROP EXTENSION
Parent topic: SQL Commands