pg_foreign_data_wrapper

The system catalog table pg_foreign_data_wrapper stores foreign-data wrapper definitions. A foreign-data wrapper is a mechanism by which you access external data residing on foreign servers.

column	type	references	description
oid	oid		The object ID
fdwname	name		Name of the foreign-data wrapper
fdwowner	oid	pg_authid.oid	Owner of the foreign-data wrapper
fdwhandler	oid	pg_proc.oid	A reference to a handler function that is responsible for supplying execution routines for the foreign-data wrapper. Zero if no handler is provided
fdwvalidator	oid	pg_proc.oid	A reference to a validator function that is responsible for checking the validity of the options provided to the foreign-data wrapper. This function also checks the options for foreign servers and user mappings using the foreign-data wrapper. Zero if no validator is provided
fdwacl	aclitem[]		Access privileges; see GRANT and REVOKE for details
fdwoptions	text[]		Foreign-data wrapper-specific options, as “keyword=value” strings