Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t1(a int primary key, b int);
create table t2(a int primary key, b int);
alter table t1 set tiflash replica 1;
alter table t2 set tiflash replica 1;
set tx_isolation="READ-COMMITTED";
begin;
explain select /*+ set_var(tidb_isolation_read_engines='tidb,tiflash'),set_var(tidb_enforce_mpp=on) */ * from t1 join t2 on t1.a=t2.b where t1.a in (1,2);

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

TiFlash plan is shown without error.

3. What did you see instead (Required)

ERROR 1815 (HY000): Internal : No access path for table 't1' is found with 'tidb_isolation_read_engines' = 'tidb,tiflash', valid values can be 'tikv'.

4. What is your TiDB version? (Required)

v8.5.1