Name

CREATE EXTENSION — install an extension

Synopsis

CREATE EXTENSION [ IF NOT EXISTS ] extension_name
    [ WITH ] [ SCHEMA schema_name ]
             [ VERSION version ]
             [ FROM old_version ]

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.

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.

old_version

FROM old_version must be specified when, and only when, you are attempting to install an extension that replaces an old style module that is just a collection of objects 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. Be careful that SCHEMA specifies the schema containing these pre-existing objects.

The value to use for old_version is determined by the extension's author, and might vary if there is more than one version of the old-style module that can be upgraded into an extension. For the standard additional modules supplied with pre-9.1 PostgreSQL™, use unpackaged for old_version when updating a module to extension style.

Examples

Install the hstore extension into the current database:

CREATE EXTENSION hstore;

Update a pre-9.1 installation of hstore into extension style:

CREATE EXTENSION hstore SCHEMA public FROM unpackaged;

Be careful to specify the schema in which you installed the existing hstore objects.