TiFlash result is wrong

[lilinghai]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

prepare some data
do random dml and check select count(*) using tiflash and tikv
upgrade from 6.17 to master, when one tiflash version is 6.1.7 and another is master, query from tiflash is wrong

mysql> begin;
Query OK, 0 rows affected (0.04 sec)

mysql> set tidb_isolation_read_engines='tiflash';
Query OK, 0 rows affected (0.03 sec)

mysql> select count(*) from t;
+----------+
| count(*) |
+----------+
| 15284754 |
+----------+
1 row in set (0.17 sec)

mysql> set tidb_isolation_read_engines='tikv';
Query OK, 0 rows affected (0.03 sec)

mysql> select count(*) from t;
+----------+
| count(*) |
+----------+
| 16117328 |
+----------+
1 row in set (0.15 sec)

mysql> commit;
Query OK, 0 rows affected (0.04 sec)

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

3. What did you see instead (Required)

4. What is your TiFlash version? (Required)

[JaySon-Huang]

Confirm it is introduced by #8854. Has been revert in the master/release-8.1 branch