## 51.23. `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` | ``pg_authid`.oid` | Owner of the foreign-data wrapper
`fdwhandler` | `oid` | ``pg_proc`.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` | ``pg_proc`.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