Oracle Error Message
QSM-02176: MV with UNION ALL in a view is too complex
Reason for the Error
If a materialized view has a view whose definition involves a UNION ALL query, then the materialized view’s defining query cannot have any clauses other than SELECT or FROM. Other clauses such as WHERE, HAVING, CONNECT BY, or GROUP BY are not allowed. Further more, the FROM clause should have only one item.
Solution
Remove any clauses besides SELECT and FROM from the materialized view’s defining query.