ORA-32442
Cannot create the materialized view REFRESH FAST if the query joins one or more external tables with one or more RDBMS tables
Cause
An attempt is being made to create the materialized view REFRESH FAST while joining one or more external tables with one or more RDBMS tables.
Action
Create the materialized view REFRESH FAST while referencing one and only one external table without any joins. Or, create the materialized view REFRESH COMPLETE.