The system catalog table pg_foreign_table contains auxiliary information about foreign tables. A foreign table is primarily represented by a pg_class entry, just like a regular table. Its pg_foreign_table entry contains the information that is pertinent only to foreign tables and not any other kind of relation.
|ftrelid||oid||pg_class.oid||OID of the pg_class entry for this foreign table.|
|ftserver||oid||pg_foreign_server.oid||OID of the foreign server for this foreign table.|
|ftoptions||text||Foreign table options, as "keyword=value" strings.|