'\" t .\" Title: CREATE EXTENSION .\" Author: The PostgreSQL Global Development Group .\" Generator: DocBook XSL Stylesheets v1.79.1 .\" Date: 2021 .\" Manual: PostgreSQL 11.12 Documentation .\" Source: PostgreSQL 11.12 .\" Language: English .\" .TH "CREATE EXTENSION" "7" "2021" "PostgreSQL 11.12" "PostgreSQL 11.12 Documentation" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" CREATE_EXTENSION \- install an extension .SH "SYNOPSIS" .sp .nf CREATE EXTENSION [ IF NOT EXISTS ] \fIextension_name\fR [ WITH ] [ SCHEMA \fIschema_name\fR ] [ VERSION \fIversion\fR ] [ FROM \fIold_version\fR ] [ CASCADE ] .fi .SH "DESCRIPTION" .PP \fBCREATE EXTENSION\fR loads a new extension into the current database\&. There must not be an extension of the same name already loaded\&. .PP Loading an extension essentially amounts to running the extension\*(Aqs script file\&. The script will typically create new SQL objects such as functions, data types, operators and index support methods\&. \fBCREATE EXTENSION\fR additionally records the identities of all the created objects, so that they can be dropped again if \fBDROP EXTENSION\fR is issued\&. .PP 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 \fBCREATE EXTENSION\fR becomes the owner of the extension for purposes of later privilege checks, as well as the owner of any objects created by the extension\*(Aqs script\&. .SH "PARAMETERS" .PP IF NOT EXISTS .RS 4 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\&. .RE .PP \fIextension_name\fR .RS 4 The name of the extension to be installed\&. PostgreSQL will create the extension using details from the file SHAREDIR/extension/\fIextension_name\fR\&.control\&. .RE .PP \fIschema_name\fR .RS 4 The name of the schema in which to install the extension\*(Aqs objects, given that the extension allows its contents to be relocated\&. The named schema must already exist\&. If not specified, and the extension\*(Aqs control file does not specify a schema either, the current default object creation schema is used\&. .sp 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\*(Aqs schema parameter\&. However, if the CASCADE clause is also given, then \fIschema_name\fR is ignored when it conflicts\&. The given \fIschema_name\fR will be used for installation of any needed extensions that do not specify schema in their control files\&. .sp 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\&. .RE .PP \fIversion\fR .RS 4 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\*(Aqs control file\&. .RE .PP \fIold_version\fR .RS 4 FROM \fIold_version\fR must be specified when, and only when, you are attempting to install an extension that replaces an \(lqold style\(rq module that is just a collection of objects not packaged into an extension\&. This option causes \fBCREATE EXTENSION\fR 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\&. .sp The value to use for \fIold_version\fR is determined by the extension\*(Aqs 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 \fIold_version\fR when updating a module to extension style\&. .RE .PP CASCADE .RS 4 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\&. .RE .SH "NOTES" .PP Before you can use \fBCREATE EXTENSION\fR to load an extension into a database, the extension\*(Aqs supporting files must be installed\&. Information about installing the extensions supplied with PostgreSQL can be found in Additional Supplied Modules\&. .PP The extensions currently available for loading can be identified from the pg_available_extensions or pg_available_extension_versions system views\&. .if n \{\ .sp .\} .RS 4 .it 1 an-trap .nr an-no-space-flag 1 .nr an-break-flag 1 .br .ps +1 \fBCaution\fR .ps -1 .br .PP Installing an extension as superuser requires trusting that the extension\*(Aqs 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 \fIsearch_path\fR during script execution, meaning that they are in the extension\*(Aqs 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\&. .PP 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\&. .sp .5v .RE .PP For information about writing new extensions, see Section\ \&38.16\&. .SH "EXAMPLES" .PP Install the hstore extension into the current database, placing its objects in schema addons: .sp .if n \{\ .RS 4 .\} .nf CREATE EXTENSION hstore SCHEMA addons; .fi .if n \{\ .RE .\} .sp Another way to accomplish the same thing: .sp .if n \{\ .RS 4 .\} .nf SET search_path = addons; CREATE EXTENSION hstore; .fi .if n \{\ .RE .\} .PP Update a pre\-9\&.1 installation of hstore into extension style: .sp .if n \{\ .RS 4 .\} .nf CREATE EXTENSION hstore SCHEMA public FROM unpackaged; .fi .if n \{\ .RE .\} .sp Be careful to specify the schema in which you installed the existing hstore objects\&. .SH "COMPATIBILITY" .PP \fBCREATE EXTENSION\fR is a PostgreSQL extension\&. .SH "SEE ALSO" ALTER EXTENSION (\fBALTER_EXTENSION\fR(7)), DROP EXTENSION (\fBDROP_EXTENSION\fR(7))