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The PostgreSQL contrib tree---------------------------This subtree contains porting tools, analysis utilities, and plug-infeatures that are not part of the core PostgreSQL system, mainlybecause they address a limited audience or are too experimental to bepart of the main source tree. This does not preclude theirusefulness.User documentation for each module appears in the main SGMLdocumentation.When building from the source distribution, these modules are notbuilt automatically, unless you build the "world" target. You canalso build and install them all by running "gmake all" and "gmakeinstall" in this directory; or to build and install just one selectedmodule, do the same in that module's subdirectory.Some directories supply new user-defined functions, operators, ortypes. To make use of one of these modules, after you have installedthe code you need to register the new SQL objects in the databasesystem by executing a CREATE EXTENSION command. In a fresh database,you can simply do CREATE EXTENSION module_name;See the PostgreSQL documentation for more information about thisprocedure.