The SQL statement that broke the limit of ‘only_full_gropy_by’ did not trigger the error normally

[rebelice]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a int, b int, c int);
select @@sql_mode; /* check SQL mode */
select case when a=1 then max(b) end as max_b from (select * from t union all select * from t) x group by c;

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

ERROR 1055 (42000): Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'x.a' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

3. What did you see instead (Required)

no error

4. What is your TiDB version? (Required)

MySQL [test]> select tidb_version();
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| tidb_version() |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Release Version: v5.2.0-alpha-720-gd9bf3bf2d
Edition: Community
Git Commit Hash: d9bf3bf
Git Branch: HEAD
UTC Build Time: 2021-08-24 06:11:04
GoVersion: go1.16.6
Race Enabled: false
TiKV Min Version: v3.0.0-60965b006877ca7234adaced7890d7b029ed1306
Check Table Before Drop: false |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.001 sec)

[tiancaiamao]

@kennytm OK, maybe I'm wrong ... or maybe I'm using some other wrong version ...
Now that I can't reproduce it neither, let's ignore it.

[AilinKid]

FD in logical union hasn't been considered