So it is a "feature. So that means that ALL queries / processes using that table should be updated from 14.3 on. That could be quite some work.
Also, I believe that by doing that to reduce the # of rows hence to enhance the performance of this table, this will force queries to be more complex and thus reducing the performance again.
But OK, nothing we can do about it. So the trick would be to look for the MAX(from_date) of records with overlapping dates.
Thanks for your answer.