@MrSylar 文档看的很细致，点赞👍
这个参数在 7.5 引入，在 6.5.10 里没有。
MySQL [(none)]> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v6.5.10
Edition: Community
Git Commit Hash: ff2feb6653846b0decd8b1d7cc0a665e128ccf26
Git Branch: heads/refs/tags/v6.5.10
UTC Build Time: 2024-06-18 15:07:37
GoVersion: go1.19.13
Race Enabled: false
TiKV Min Version: 6.2.0-alpha
Check Table Before Drop: false
Store: tikv
1 row in set (0.001 sec)
MySQL [(none)]> select @@tidb_enable_async_merge_global_stats;
ERROR 1193 (HY000): Unknown system variable 'tidb_enable_async_merge_global_stats'
MySQL [(none)]>
MySQL [(none)]> select tidb_version()\G
*************************** 1. row ***************************
tidb_version(): Release Version: v7.5.0
Edition: Community
Git Commit Hash: 069631e2ecfedc000ffb92c67207bea81380f020
Git Branch: heads/refs/tags/v7.5.0
UTC Build Time: 2023-11-24 08:50:14
GoVersion: go1.21.3
Race Enabled: false
Check Table Before Drop: false
Store: tikv
1 row in set (0.029 sec)
MySQL [(none)]> select @@tidb_enable_async_merge_global_stats;
+----------------------------------------+
| @@tidb_enable_async_merge_global_stats |
+----------------------------------------+
| 1 |
+----------------------------------------+
1 row in set (0.003 sec)
所以 6.5.10 的 RN 有点问题。
