MySQL Bugs: #113016: sys database can't select when use utf8mb4_general

Bug #113016	sys database can't select when use utf8mb4_general_ci
Submitted:	9 Nov 2023 6:22	Modified:	9 Nov 2023 11:49
Reporter:	chong zhang	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	MySQL Server: SYS Schema	Severity:	S1 (Critical)
Version:	8.0.25	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
The database of sys cannot be queried anything on table because default_COLLATION_FOR_UTf8MB4 is set to UTF8MB4_general_ci.

How to repeat:
please put the Variable_name of default_collation_for_utf8mb4 to utf8mb4_general_ci and try to query anything on tables from database of sys.

Suggested fix:
please fix this bug or Disable parameter modification.

mysql sys database can't select data when use utf8mb4_general_ci,I found that changing the collation rules of sys can solve the problem.

Can I rebuild the collation rules of the sys database?  What would be the impact if I did this？

eg:
1、
$ mysqldump  --user=root  --default-character-set=utf8    --password='xxx' --socket=/opt/mysql3303/mysql.sock  --single-transaction --hex-blob  --set-gtid-purged=off   --skip-tz-utc  --routines --triggers --events --add-drop-database --databases sys > sys_dump.sql

2、
$ sed -i "s#utf8mb4_0900_ai_ci#utf8mb4_general_ci#g" sys_dump.sql

3、
mysql> set session default_collation_for_utf8mb4=utf8mb4_0900_ai_ci;
mysql> source /xxx/sys_dump.sql

Please do not submit the same bug more than once. An existing bug report already describes this very problem. Even if you feel that your issue is somewhat different, the resolution is likely
to be the same. Because of this, we hope you add your comments to the original bug instead.

You have filed the same bug already:

https://bugs.mysql.com/bug.php?id=107538

Thank you for your interest in MySQL.