pg_foreign_data_wrapper — PostgreSQL system catalog

Summary

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.

(Description quoted from the official PostgreSQL documentation.)

Columns

The pg_foreign_data_wrapper system catalog exposes the following columns (names, types and descriptions are taken verbatim from the PostgreSQL documentation):

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
fdwconnection oid references pg_proc.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 ddl_priv for details
fdwoptions text[]
Foreign-data wrapper specific options, as “keyword=value” strings

Related catalogs

This object references the following other system catalogs:

fdwowner → pg_authid
fdwhandler → pg_proc

Version applicability

Present in PostgreSQL 17, 18, 19 (verified against each release’s documentation). This is a long-standing system object that also exists in earlier PostgreSQL releases.

Related & references

Reference: PostgreSQL documentation — pg_foreign_data_wrapper.