Extensions

This chapter contain information regarding on the optional components found in the share/extension directory of the QHB distribution. These include porting tools, analysis utilities, and plug-in features that are not part of the core QHB 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 qhb-contrib package. You need to install it following description of the installation.

Many components supply new user-defined functions, operators, or types. 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 CREATE EXTENSION 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 each database that you want the extension's facilities to be available in. Alternatively, run it in database template1 so that the extension will be copied into subsequently-created databases by default.

For all extensions, the CREATE EXTENSIONcommand 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, pg_trgm, 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 shared_preload_libraries. See the documentation of each component for details.

Extensions

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