pg_foreign_data_wrapper
   The catalog pg_foreign_data_wrapper stores
   foreign-data wrapper definitions.  A foreign-data wrapper is the
   mechanism by which external data, residing on foreign servers, is
   accessed.
  
Table 51.23. pg_foreign_data_wrapper Columns
| Name | Type | References | Description | 
|---|---|---|---|
| oid | oid | Row identifier | |
| fdwname | name | Name of the foreign-data wrapper | |
| fdwowner | oid |  | Owner of the foreign-data wrapper | 
| fdwhandler | oid |  | References a handler function that is responsible for supplying execution routines for the foreign-data wrapper. Zero if no handler is provided | 
| fdwvalidator | oid |  | References a validator function that is responsible for checking the validity of the options given to the foreign-data wrapper, as well as options for foreign servers and user mappings using the foreign-data wrapper. Zero if no validator is provided | 
| fdwacl | aclitem[] | Access privileges; see Section 5.7 for details | |
| fdwoptions | text[] | Foreign-data wrapper specific options, as “keyword=value” strings |