set @@tidb_enable_noop_functions='OFF';
create table t(a int key, b int);
insert into t values (1, 1), (2, 2);
select * from t where a=1 lock in share mode;
select * from t where b=1 lock in share mode;

tidb> select * from t where a=1 lock in share mode;
+---+------+
| a | b    |
+---+------+
| 1 |    1 |
+---+------+
1 row in set (5.80 sec)

tidb> select * from t where b=1 lock in share mode;
ERROR 1235 (42000): function LOCK IN SHARE MODE has only noop implementation in tidb now, use tidb_enable_noop_functions to enable these functions