---
title: "pg_foreign_data_wrapper"
id: catalog-pg-foreign-data-wrapper
pg_version: "20devel"
---

<a id="catalog-pg-foreign-data-wrapper"></a>

## 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. 

**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](catalog-pg-authid.md).`oid`) | Owner of the foreign-data wrapper |
| `fdwhandler` `oid` (references [pg_proc](catalog-pg-proc.md).`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](catalog-pg-proc.md).`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 |
| `fdwconnection` `oid` (references [pg_proc](catalog-pg-proc.md).`oid`) | References a connection function that is responsible for creating a connection string for a subscription when the subscription uses a server based on this foreign-data wrapper. Zero if this foreign-data wrapper does not support subscription connections. |
| `fdwacl` `aclitem[]` | Access privileges; see [Section 5.9](ddl-priv.md) for details |
| `fdwoptions` `text[]` | Foreign-data wrapper specific options, as "keyword=value" strings |