## 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

Column Type Description
`oid` `oid` Row identifier
`fdwname` `name` Name of the foreign-data wrapper
`fdwowner` `oid` (references `pg_authid`.`oid`) Owner of the foreign-data wrapper
`fdwhandler` `oid` (references `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` (references `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