The implementation strategy for predicate realignment can drop non-column equi join predicates and predicates involving the same column reused multiple times.

i.e.
create local temporary table x (e1 string, e2 integer, primary key (e1));
create local temporary table x1 (e1 string, e2 integer)
...
select x.e1 from x inner join x1 on x.e1 = x1.e1 and upper(x.e1) = x1.e2

May end up not applying the upper predicate.