RIGHT JOINs will not produce a correct data structure
RIGHT JOINs cannot produce correct results with the current implementation. RIGHT JOINs mean that the "main" table may have empty records related to the JOINed tables. But Data Query requires every record to have a uid. So it cannot work. Perhaps it is possible to work around that by having empty records of the main table have uid = 0.
This is not critical IMO because RIGHT JOINs are rather rare.