CREATE USER MAPPING
Name
CREATE USER MAPPING -- define a new mapping of a user to a foreign server
Synopsis
CREATE USER MAPPING FOR { user_name | USER | CURRENT_USER | PUBLIC }
    SERVER server_name
    [ OPTIONS ( option 'value' [ , ... ] ) ]Description
Note: The following description applies only to Postgres-XC
   USER MAPPING has not been supported
   by Postgres-XC yet.  This command may be supported
   in the future releases.