NULL elements aren't dealed properly

[neumyor]

In TPCH situation, executing SQL below:

select c.c_custkey, max(o.o_totalprice) from orders o left join customer c on o.o_orderkey = c.c_custkey group by c.c_custkey ;

will throw Cannot invoke "Object.equals(Object)" because the return value of "com.hufudb.onedb.data.storage.ArrayRow.get(int)" is null

However, executing SQL like :

select c.c_custkey, max(o.o_totalprice) from orders o join customer c on o.o_orderkey = c.c_custkey group by c.c_custkey ;

is totally ok.

[neumyor]

null element is not dealed properly when using ORDER BY

select c.c_custkey, max(o.o_totalprice) 
from orders o 
left join customer c 
on o.o_orderkey = c.c_custkey 
group by c.c_custkey 
order by c.c_custkey ;