# Additional Supplied Modules and Extensions

This appendix and the next one contain information on the optional components found in the `contrib` directory of the PostgreSQL distribution. These include porting tools, analysis utilities, and plug-in features that are not part of the core PostgreSQL system. They are separate mainly because they address a limited audience or are too experimental to be part of the main source tree. This does not preclude their usefulness.

This appendix covers extensions and other server plug-in module libraries found in `contrib`. contrib-prog covers utility programs.

When building from the source distribution, these optional components are not built automatically, unless you build the "world" target (see build). You can build and install all of them by running:

    make
    make install

in the `contrib` directory of a configured source tree; or to build and install just one selected module, do the same in that module's subdirectory. Many of the modules have regression tests, which can be executed by running:

    make check

before installation or

    make installcheck

once you have a PostgreSQL server running.

If you are using a pre-packaged version of PostgreSQL, these components are typically made available as a separate subpackage, such as `postgresql-contrib`.

Many components supply new user-defined functions, operators, or types, packaged as extensions. To make use of one of these extensions, after you have installed the code you need to register the new SQL objects in the database system. This is done by executing a sql-createextension command. In a fresh database, you can simply do

    CREATE EXTENSION extension_name;

This command registers the new SQL objects in the current database only, so you need to run it in every database in which you want the extension's facilities to be available. Alternatively, run it in database `template1` so that the extension will be copied into subsequently-created databases by default.

For all extensions, the `CREATE EXTENSION` command must be run by a database superuser, unless the extension is considered trusted. Trusted extensions can be run by any user who has `CREATE` privilege on the current database. Extensions that are trusted are identified as such in the sections that follow. Generally, trusted extensions are ones that cannot provide access to outside-the-database functionality.

The following extensions are trusted in a default installation:

- btree-gin
- btree-gist
- citext
- cube
- dict-int
- fuzzystrmatch
- hstore
- intarray
- isn
- lo
- ltree
- pgcrypto
- pgtrgm
- seg
- tablefunc
- tcn
- tsm-system-rows
- tsm-system-time
- unaccent
- uuid-ossp

Many extensions allow you to install their objects in a schema of your choice. To do that, add `SCHEMA `schema_name`` to the `CREATE EXTENSION` command. By default, the objects will be placed in your current creation target schema, which in turn defaults to `public`.

Note, however, that some of these components are not extensions in this sense, but are loaded into the server in some other way, for instance by way of guc-shared-preload-libraries. See the documentation of each component for details.

&amcheck; &auth-delay; &auto-explain; &basebackup-to-shell; &basic-archive; &bloom; &btree-gin; &btree-gist; &citext; &cube; &dblink; &dict-int; &dict-xsyn; &earthdistance; &file-fdw; &fuzzystrmatch; &hstore; &intagg; &intarray; &isn; &lo; <ree; &pageinspect; &passwordcheck; &pgbuffercache; &pgcrypto; &pgfreespacemap; &pglogicalinspect; &pgoverexplain; &pgprewarm; &pgrowlocks; &pgstatstatements; &pgstattuple; &pgsurgery; &pgtrgm; &pgvisibility; &pgwalinspect; &postgres-fdw; &seg; &sepgsql; &contrib-spi; &sslinfo; &tablefunc; &tcn; &test-decoding; &tsm-system-rows; &tsm-system-time; &unaccent; &uuid-ossp; &xml2;

## Additional Supplied Programs

This appendix and the previous one contain information regarding the modules that can be found in the `contrib` directory of the PostgreSQL distribution. See contrib for more information about the `contrib` section in general and server extensions and plug-ins found in `contrib` specifically.

This appendix covers utility programs found in `contrib`. Once installed, either from source or a packaging system, they are found in the `bin` directory of the PostgreSQL installation and can be used like any other program.

## Client Applications

This section covers PostgreSQL client applications in `contrib`. They can be run from anywhere, independent of where the database server resides. See also reference-client for information about client applications that are part of the core PostgreSQL distribution.

&oid2name; &vacuumlo;

## Server Applications

Some applications run on the PostgreSQL server itself. Currently, no such applications are included in the `contrib` directory. See also reference-server for information about server applications that are part of the core PostgreSQL distribution.