CREATE EXTENSION
Synopsis
CREATE EXTENSION [ IF NOT EXISTS ]extension_name [ WITH ] [ SCHEMAschema_name ] [ VERSIONversion ] [ FROMold_version ]
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 newSQL 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 ifDROP 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 needed. The user who runsCREATE 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's script.
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 fileSHAREDIR/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
FROMold_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 causesCREATE EXTENSION to run an alternative installation script that absorbs the existing objects into the extension, instead of creating new objects. Be careful thatSCHEMA specifies the schema containing these pre-existing objects.
The value to use forold_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-9.1PostgreSQL, useunpackaged forold_version when updating a module to extension style.
Notes
Before you can useCREATE EXTENSION to load an extension into a database, the extension's supporting files must be installed. Information about installing the extensions supplied withPostgreSQL can be found inAdditional Supplied Modules.
The extensions currently available for loading can be identified from thepg_available_extensions orpg_available_extension_versions system views.
For information about writing new extensions, seeSection 35.15.
Examples
Install thehstore extension into the current database:
CREATE EXTENSION hstore;
Update a pre-9.1 installation ofhstore into extension style:
CREATE EXTENSION hstore SCHEMA public FROM unpackaged;
Be careful to specify the schema in which you installed the existinghstore objects.