ALTER_USER_MAPPING - change the definition of a user mapping

ALTERUSERMAPPING conforms to ISO/IEC 9075-9 (SQL/MED). There is a subtle syntax issue: The standard
       omits the FOR key word. Since both CREATE USER MAPPING and DROP USER MAPPING use FOR in analogous
       positions, and IBM DB2 (being the other major SQL/MED implementation) also requires it for ALTER USER
       MAPPING, PostgreSQL diverges from the standard here in the interest of consistency and interoperability.

ALTERUSERMAPPING changes the definition of a user mapping.

       The owner of a foreign server can alter user mappings for that server for any user. Also, a user can
       alter a user mapping for their own user name if USAGE privilege on the server has been granted to the
       user.

       Change the password for user mapping bob, server foo:

           ALTER USER MAPPING FOR bob SERVER foo OPTIONS (SET password 'public');

       ALTER_USER_MAPPING - change the definition of a user mapping

user_name
           User name of the mapping.  CURRENT_ROLE, CURRENT_USER, and USER match the name of the current user.
           PUBLIC is used to match all present and future user names in the system.

       server_name
           Server name of the user mapping.

       OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ] )
           Change options for the user mapping. The new options override any previously specified options.  ADD,
           SET, and DROP specify the action to be performed.  ADD is assumed if no operation is explicitly
           specified. Option names must be unique; options are also validated by the server's foreign-data
           wrapper.

       CREATE USER MAPPING (CREATE_USER_MAPPING(7)), DROP USER MAPPING (DROP_USER_MAPPING(7))

PostgreSQL 17.5                                       2025                                 ALTERUSERMAPPING(7)

       ALTER USER MAPPING FOR { user_name | USER | CURRENT_ROLE | CURRENT_USER | SESSION_USER | PUBLIC }
           SERVER server_name
           OPTIONS ( [ ADD | SET | DROP ] option ['value'] [, ... ] )