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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 VALIDATOR 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
       [create_server(7)], CREATE USER MAPPING [create_user_mapping(7)]