'\" t
.\"     Title: CREATE EXTENSION
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 2016
.\"    Manual: PostgreSQL 9.5.2 Documentation
.\"    Source: PostgreSQL 9.5.2
.\"  Language: English
.\"
.TH "CREATE EXTENSION" "5sql" "2016" "PostgreSQL 9.5.2" "PostgreSQL 9.5.2 Documentation"
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.nh
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.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 ]
.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
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
.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\&.
.PP
For information about writing new extensions, see
Section 35.15, \(lqPackaging Related Objects into an Extension\(rq, in the documentation\&.
.SH "EXAMPLES"
.PP
Install the
hstore
extension into the current database:
.sp
.if n \{\
.RS 4
.\}
.nf
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(5)), DROP EXTENSION (\fBDROP_EXTENSION\fR(5))