A domain is the entire set of data for a level of aggregation.
Within a whole universe, measure aggregations can be calculated based on the set of fragments.
When some fragments are missing, the Oracle BI Server assumes that it does not have the whole universe of fragments, it would be incorrect to calculate aggregate rollups and in this case, the server returns NULL as measure aggregates.
- Horizontal fragment missing (For one year but not for an others)
- The set of query columns differ across the fragments