CREATE EXTENSION — 安裝延伸套件
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's script file. The script will typically create new SQL objects such as functions, data types, operators and index support methods.
CREATE EXTENSIONadditionally records the identities of all 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 needed. 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's script.
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.
The name of the extension to be installed. PostgreSQL will create the extension using details from the file
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.
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 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
old_version when updating a module to extension style.
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.
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.
For information about writing new extensions, see Section 37.15.
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
CREATE EXTENSION 是 PostgreSQL 的延伸功能。