Group by not work for negative

[BohuTANG]

Summary

create table t(tiny TINYINT);
insert into t values(-1);
select sum(tiny) from t group by tiny; -- no result here

This is works:

create table t2(a tinyint);
insert into t2 values(1);
mysql> select sum(a) from t2 group by a;
+--------+
| sum(a) |
+--------+
|      1 |
+--------+

[BohuTANG]

I have add a new data type stateless category: #4892

We should do some checks for each data type(4892 is just an outline draft, there is still a lot of work to do, I will first merge it):

• Bound check
• Conversion check(Explicit Conversion and Implicit Conversion)
• Group by check
• Others?

[sundy-li]

Bugs to u8/u16 keys in hashmap.

MySQL [(none)]> select b::Int64 as b ,count(1)  from t2 group by b;
+------+---------+
| b    | count() |
+------+---------+
|   -1 |       1 |
|    4 |       1 |
|   -3 |       1 |
|    2 |       1 |
+------+---------+
4 rows in set (0.033 sec)

MySQL [(none)]> select b::Int16 as b ,count(1)  from t2 group by b;
+------+---------+
| b    | count() |
+------+---------+
|    2 |       1 |
|    4 |       1 |
|   -3 |       1 |
+------+---------+
3 rows in set (0.033 sec)

[sundy-li]

 fn aggregate_state(&self) -> Self::State {
        Self::State::create(u8::MAX as usize)
    }

Seems related to u8::MAX, should be u8::MAX as usize + 1