ALTER FOREIGN DATA WRAPPER

Changes the definition of a foreign-data wrapper.

Synopsis

ALTER FOREIGN DATA WRAPPER <name>
    [ HANDLER <handler_function> | NO HANDLER ]
    [ VALIDATOR <validator_function> | NO VALIDATOR ]
    [ OPTIONS ( [ ADD | SET | DROP ] <option> ['<value>'] [, ... ] ) ]

ALTER FOREIGN DATA WRAPPER <name> OWNER TO <new_owner>
ALTER FOREIGN DATA WRAPPER <name> RENAME TO <new_name>

Description

ALTER FOREIGN DATA WRAPPER changes the definition of a foreign-data wrapper. The first form of the command changes the support functions or generic options of the foreign-data wrapper. Greenplum Database requires at least one clause. The second and third forms of the command change the owner or name of the foreign-data wrapper.

Only superusers can alter foreign-data wrappers. Additionally, only superusers can own foreign-data wrappers

Parameters

name

The name of an existing foreign-data wrapper.

HANDLER handler_function

Specifies a new handler function for the foreign-data wrapper.

NO HANDLER

Specifies that the foreign-data wrapper should no longer have a handler function.

Note

You cannot access a foreign table that uses a foreign-data wrapper with no handler.

VALIDATOR validator_function

Specifies a new validator function for the foreign-data wrapper.

Options to the foreign-data wrapper, servers, and user mappings may become invalid when you change the validator function. You must make sure that these options are correct before using the modified foreign-data wrapper. Note that Greenplum Database checks any options specified in this ALTER FOREIGN DATA WRAPPER command using the new validator.

NO VALIDATOR

Specifies that the foreign-data wrapper should no longer have a validator function.

OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ] )

Change the foreign-data wrapper's options. ADD, SET, and DROP specify the action to perform. If no operation is explicitly specified, the default operation is ADD. Option names must be unique. Greenplum Database validates names and values using the foreign-data wrapper's validator function, if any.

OWNER TO new_owner

Specifies the new owner of the foreign-data wrapper. Only superusers can own foreign-data wrappers.

RENAME TO new_name

Specifies the new name of the foreign-data wrapper.

Examples

Change the definition of a foreign-data wrapper named dbi by adding a new option named foo, and removing the option named bar:

ALTER FOREIGN DATA WRAPPER dbi OPTIONS (ADD foo '1', DROP 'bar');

Change the validator function for a foreign-data wrapper named dbi to bob.myvalidator:

ALTER FOREIGN DATA WRAPPER dbi VALIDATOR bob.myvalidator;

Compatibility

ALTER FOREIGN DATA WRAPPER conforms to ISO/IEC 9075-9 (SQL/MED), with the exception that the HANDLER, VALIDATOR, OWNER TO, and RENAME TO clauses are Greenplum Database extensions.

See Also

CREATE FOREIGN DATA WRAPPER, DROP FOREIGN DATA WRAPPER

Parent topic: SQL Commands