# Basic math operations with SUM() - unexpected values

we had this problem: updated version of **MariaDB Columnstore** from **1.2.2** to **1.2.4** and nonsense started.

We have these columns `col1, col2`

both are `DECIMAL(15,3)`

there was already working query to calculate these two columns (see alias `A`

) and this wasn't calculating right when `col2`

had zero sum - after db update. Alias `B`

was first approach which didn't help. And `C`

was solution for proper working.

I want to know explanation why this happened and what caused this behaviour.

```
SELECT
id,
SUM(col1) AS c1,
SUM(col2) AS c2,
SUM(col1 - col2) AS A,
SUM(CAST(col1 AS DOUBLE) - CAST(col2 AS DOUBLE)) AS B,
SUM(CAST(col1 AS DECIMAL(15,3)) - CAST(col2 AS DECIMAL(15,3))) AS C
FROM table GROUP BY id
```

1.2.2:

```
+----+----------+--------+-----------+
| id | c1 | c2 | A |
+----+----------+--------+-----------+
| 1 | 1199.940 | 0.000 | 1199.940 |
| 2 | 979.860 | 69.990 | 909.870 |
+----+----------+--------+-----------+
```

1.2.4 with extra SUMs

```
+----+----------+--------+-----------------------+---------+-----------+
| id | c1 | c2 | A | B | C |
+----+----------+--------+-----------------------+---------+-----------+
| 1 | 1199.940 | 0.000 | -9223372036853575.868 | 0 | 1199.940 |
| 2 | 979.860 | 69.990 | 909.870 | 909.87 | 909.870 |
+----+----------+--------+-----------------------+---------+-----------+
```