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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 VALIDATOR is specified, then options  will  not  be
              checked  at creation time. (Foreign-data wrappers will possibly ignore or reject invalid option specifi-
              cations 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 wrap-
       pers, 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 functional-
       ity 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_wrap-
       per(7)], CREATE SERVER [create_server(7)], CREATE USER MAPPING [create_user_mapping(7)]



SQL - Language Statements         2014-02-17    CREATE FOREIGN DATA WRAPPER(7)