| ERROR | MV with UNION ALL in a view is too complex |
| CAUSE | If a materialized view has a view whose definition involves a UNION ALL query, then the materialized views 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. |
| ACTION | Remove any clauses besides SELECT and FROM from the materialized views defining query. |