pg_user_mapping
   The catalog pg_user_mapping stores
   the mappings from local user to remote.  Access to this catalog is
   restricted from normal users, use the view
   pg_user_mappings
   instead.
  
Table 52.64. pg_user_mapping Columns
| Name | Type | References | Description | 
|---|---|---|---|
| oid | oid | Row identifier (hidden attribute; must be explicitly selected) | |
| umuser | oid |  | OID of the local role being mapped, 0 if the user mapping is public | 
| umserver | oid |  | The OID of the foreign server that contains this mapping | 
| umoptions | text[] | User mapping specific options, as “keyword=value” strings |