> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/internals/catalogs/catalog-pg-foreign-data-wrapper.md).
# 52.23. 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 52.23. `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 5.8 for details
|
| fdwoptions text\[]
Foreign-data wrapper specific options, as “keyword=value” strings
|
***
原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/catalog-pg-foreign-data-wrapper.html)（英文原文，待翻譯）
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