05-18-2017 09:58 PM - edited 05-22-2017 01:28 AM
05-19-2017 02:23 PM
i observed teh exact opposite performance. with the join any attribute that was there was renamed and added as a new attributs so the files size was huge.
when i used union it add teh new example uner teh appropriate atribut if it existed and only create a new atribute when it did not already exist in set it was being joined with.