For some flattened subqueries, certain join orders are possible only if a sort is later used to remove duplicate results. When one of these join orders is considered, the following message is printed right after the join permutation order is printed:
2 - 0 - 1 - This join order created while converting an exists join to a regular join, which can happen for subqueries, referential integrity, and select distinct.
For more information on subqueries and join orders, see “Flattened subqueries using duplicate elimination”.
