CREATE FOREIGN DATA 
WRAPPER(7)					   SQL Commands 				    CREATE FOREIGN DATA WRAPPER(7)

NAME

       CREATE FOREIGN DATA WRAPPER - define a new foreign-data wrapper

SYNOPSIS

       CREATE FOREIGN DATA WRAPPER name
	   [ VALIDATOR valfunction | NO VALIDATOR ]
	   [ OPTIONS ( option 'value' [, ... ] ) ]

DESCRIPTION

       CREATE FOREIGN DATA WRAPPER creates a new foreign-data wrapper. The user who defines a foreign-data wrapper becomes its owner.

       The foreign-data wrapper name must be unique within the database.

       Only superusers can create foreign-data wrappers.

PARAMETERS

       name   The name of the foreign-data wrapper to be created.

       VALIDATOR valfunction
	      valfunction  is  the name of a previously registered function that will be called to check the generic options given to the foreign-
	      data wrapper, as well as to foreign servers and user mappings using the foreign-data wrapper. If no validator function or NO VALIDA-
	      TOR  is  specified, then options will not be checked at creation time. (Foreign-data wrappers will possibly ignore or reject invalid
	      option specifications at run time, depending on the implementation.) The validator function must take two  arguments:  one  of  type
	      text[],  which will contain the array of options as stored in the system catalogs, and one of type oid, which will be the OID of the
	      system catalog containing the options. The return type is ignored; the function should indicate invalid options using the  ereport()
	      function.

       OPTIONS ( option 'value' [, ... ] )
	      This  clause  specifies  options for the new foreign-data wrapper.  The allowed option names and values are specific to each foreign
	      data wrapper and are validated using the foreign-data wrapper library. Option names must be unique.

NOTES

       At the moment, the foreign-data wrapper functionality is very rudimentary. The purpose of foreign-data wrappers, foreign servers, and  user
       mappings  is  to  store	this  information in a standard way so that it can be queried by interested applications.  One such application is
       dblink; see in the documentation. The functionality to actually query external data through a foreign-data wrapper library does	not  exist
       yet.

       There  is  currently one foreign-data wrapper validator function provided: postgresql_fdw_validator, which accepts options corresponding to
       libpq connection parameters.

EXAMPLES

       Create a foreign-data wrapper dummy:

       CREATE FOREIGN DATA WRAPPER dummy;

       Create a foreign-data wrapper postgresql with validator function postgresql_fdw_validator:

       CREATE FOREIGN DATA WRAPPER postgresql VALIDATOR postgresql_fdw_validator;

       Create a foreign-data wrapper mywrapper with some options:

       CREATE FOREIGN DATA WRAPPER mywrapper
	   OPTIONS (debug 'true');

COMPATIBILITY

       CREATE FOREIGN DATA WRAPPER conforms to ISO/IEC 9075-9 (SQL/MED), with the exception that the VALIDATOR clause  is  an  extension  and  the
       clauses LIBRARY and LANGUAGE are not yet implemented in PostgreSQL.

       Note, however, that the SQL/MED functionality as a whole is not yet conforming.

SEE ALSO

       ALTER  FOREIGN  DATA WRAPPER [alter_foreign_data_wrapper(7)], DROP FOREIGN DATA WRAPPER [drop_foreign_data_wrapper(7)], CREATE SERVER [cre-
       ate_server(7)], CREATE USER MAPPING [create_user_mapping(7)]

SQL - Language Statements					    2010-05-14					    CREATE FOREIGN DATA WRAPPER(7)