private boolean isStructuralDataColumn(final Column column) {
        return hasFilter(column) || (column.getGroup() != null && column.getGroup() >= 0);
    }
A column affects the structure of the stored data by either filtering the incoming data with include/exclude
rules or by grouping the data.

@param column The column to test to see if it is structural.
@return True if the column is structural, false otherwise.
stroom-query/stroom-query-common/src/main/java/stroom/query/common/v2/ColumnMap.java