Different precision for window funtion when using unparallel hashagg.

[wshwsh12]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

set tidb_hashagg_final_concurrency =1 ;
set tidb_hashagg_partial_concurrency =1 ;
drop table sales;
CREATE TABLE sales(id INT AUTO_INCREMENT PRIMARY KEY, `date` DATE, sale INT);
INSERT INTO sales(`date`, sale) VALUES
('2017-03-01', 200),
('2017-04-01', 300),
('2017-05-01', 400),
('2017-06-01', 200),
('2017-07-01', 600),
('2017-08-01', 100),
('2017-03-01', 400),
('2017-04-01', 300),
('2017-05-01', 500),
('2017-06-01', 400),
('2017-07-01', 600),
('2017-08-01', 150);
set sql_mode='';
SELECT MONTH(date), SUM(sale),
AVG(SUM(sale)) OVER w AS sliding_avg FROM sales GROUP BY MONTH(date)
WINDOW w AS (ORDER BY MONTH(date)
RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING)
ORDER BY AVG(SUM(sale)) OVER (ORDER BY MONTH(date)
RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING),
MONTH(date);

2. What did you expect to see? (Required)

+-------------+-----------+-------------+
| MONTH(date) | SUM(sale) | sliding_avg |
+-------------+-----------+-------------+
|           3 |       600 |    600.0000 |
|           7 |      1200 |    683.3333 |
|           4 |       600 |    700.0000 |
|           5 |       900 |    700.0000 |
|           8 |       250 |    725.0000 |
|           6 |       600 |    900.0000 |
+-------------+-----------+-------------+
6 rows in set (0.001 sec)

3. What did you see instead (Required)

+-------------+-----------+-------------+
| MONTH(date) | SUM(sale) | sliding_avg |
+-------------+-----------+-------------+
|           3 |  600.0000 |    600.0000 |
|           7 | 1200.0000 |    683.3333 |
|           4 |  600.0000 |    700.0000 |
|           5 |  900.0000 |    700.0000 |
|           8 |  250.0000 |    725.0000 |
|           6 |  600.0000 |    900.0000 |
+-------------+-----------+-------------+
6 rows in set (0.002 sec)

4. What is your TiDB version? (Required)

master, v5.0,v5.1,v4.0

[Yisaer]

/assign

[fuzhe1989]

Hi @Yisaer, do you have any progress on this bug?

[zanmato1984]

Adjusting severity to minor.