MySQL Bugs: #108374: simple float type sum calculations produce unexpected results

Bug #108374	simple float type sum calculations produce unexpected results
Submitted:	3 Sep 2022 6:38	Modified:	3 Sep 2022 7:04
Reporter:	Eimar Koort	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: General	Severity:	S3 (Non-critical)
Version:	8.0.26	OS:	Other (Rocky 9)
Assigned to:		CPU Architecture:	x86

Description:
Taking sum from float type produces unexptected answers. 

How to repeat:
mysql> create table bla(mycol float);
mysql> desc bla;
+-------+-------+------+-----+---------+-------+
| Field | Type  | Null | Key | Default | Extra |
+-------+-------+------+-----+---------+-------+
| mycol | float | YES  |     | NULL    |       |
+-------+-------+------+-----+---------+-------+

Insert two numbers into this table and select sum from them. Combination of '0' and '0' produces '0', '0' and '1' produces '1', '0' and '1.0' produces '1' as expected.

Now it goes weird.

mysql> insert into  bla values ('1.01');
mysql> insert into  bla values ('1');

mysql> select * from bla;
+-------+
| mycol |
+-------+
|  1.01 |
|     1 |
+-------+
mysql> select sum(mycol) from bla ;
+-------------------+
| sum(mycol)        |
+-------------------+
| 2.009999990463257 |
+-------------------+

I would expect it to return "2.01" as an answer.

After reading (!) documentation i'll close this bug.

https://dev.mysql.com/doc/refman/8.0/en/problems-with-float.html

Thanks.