KohanaPHP » Kohana v3.x

Currently ORM __set method checks the previous value to see if it was truly changed before marking the column. This means save_all() method calls will not work for values that are set to their default state (i.e. the column is initially 0 and you try updating all to 0), and will prevent save() method calls from updating columns which remain the same.

The only downside to changing this functionality is having an UPDATE on records that sets the value to what it was previously. I see this drawback as relatively minor compared to the problems experienced.