pg_user_mappings

The pg_user_mappings view provides access to information about user mappings. This view is essentially a public-readble view of the pg_user_mapping system catalog table that omits the options field if the user does not have access rights to view it.

column	type	references	description
umid	oid	pg_user_mapping.oid	OID of the user mapping.
srvid	oid	pg_foreign_server.oid	OID of the foreign server that contains this mapping.
srvname	text	pg_foreign_server.srvname	Name of the foreign server.
umuser	oid	pg_authid.oid	OID of the local role being mapped, 0 if the user mapping is public.
usename	name		Name of the local user to be mapped.
umoptions	text[]		User mapping-specific options, as “keyword=value” strings.