CREATE FOREIGN DATA WRAPPER(7)
NAME
CREATE_FOREIGN_DATA_WRAPPER - define a new foreign-data wrapper
SYNOPSIS
CREATE FOREIGN DATA WRAPPER name
[ HANDLER handler_function | NO HANDLER ]
[ VALIDATOR validator_function | 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.
HANDLER handler_function
handler_function is the name of a previously registered function
that will be called to retrieve the execution functions for foreign
tables. The handler function must take no arguments, and its return
type must be fdw_handler.
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
validator_function 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 options for foreign servers, user
mappings and foreign tables 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 report
invalid options using the ereport(ERROR) 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's
validator function. Option names must be unique.
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
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))
PostgreSQL 9.4.15 2017 CREATE FOREIGN DATA WRAPPER(7)
PostgreSQL 9.4.15 - Generated Mon Nov 27 14:44:12 CST 2017