create_foreign_data_wrapper(7)

NAME#

CREATE_FOREIGN_DATA_WRAPPER - define a new foreign-data wrapper

SYNOPSIS#

CREATE FOREIGN DATA WRAPPER \nname\n
\n
    [ HANDLER \nhandler_function\n | NO HANDLER ]
\n
    [ VALIDATOR \nvalidator_function\n | NO VALIDATOR ]
\n
    [ OPTIONS ( \noption\n '\nvalue\n' [, ... ] ) ]

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

HANDLER handler_function

It is possible to create a foreign-data wrapper with no handler function, but foreign tables using such a wrapper can only be declared, not accessed.

VALIDATOR validator_function

OPTIONS ( option 'value' [, ... ] )

NOTES#

PostgreSQL's foreign-data functionality is still under active development. Optimization of queries is primitive (and mostly left to the wrapper, too). Thus, there is considerable room for future performance improvements.

EXAMPLES#

Create a useless foreign-data wrapper dummy:

CREATE FOREIGN DATA WRAPPER dummy;

Create a foreign-data wrapper file with handler function file_fdw_handler:

CREATE FOREIGN DATA WRAPPER file HANDLER file_fdw_handler;

Create a foreign-data wrapper mywrapper with some options:

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

COMPATIBILITY#

CREATE FOREIGN DATA WRAPPER conforms to ISO/IEC 9075-9 (SQL/MED), with the exception that the HANDLER and VALIDATOR clauses are extensions and the standard clauses LIBRARY and LANGUAGE are not 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)), CREATE FOREIGN TABLE (CREATE_FOREIGN_TABLE(7))