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 for‐
eign-data wrapper, as well as to foreign servers and user map‐
pings 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 argu‐
ments: 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 indi‐
cate 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 rudimen‐
tary. 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 pro‐
vided: 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 post‐
gresql_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 FOR‐
EIGN DATA WRAPPER [drop_foreign_data_wrapper(7)], CREATE SERVER [cre‐
ate_server(7)], CREATE USER MAPPING [create_user_mapping(7)]
SQL - Language Statements 2013-04-02 CREATE FOREIGN DATA WRAPPER(7)