Range Locking: individual rows are locked when scanning PK

create table ten(a int primary key);

insert into ten values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table one_k(a int primary key);

insert into one_k select A.a + B.a* 10 + C.a * 100 from ten A, ten B, ten C;

create table t1 (

  pk int primary key,

  a int

);

insert into t1 select a,a from one_k;

begin;

update t1 set a=a+10 where pk between 10 and 20;

select * from information_schema.rocksdb_locks;

+------------------+----------------+-----------------------------------------+------+                                                       

| COLUMN_FAMILY_ID | TRANSACTION_ID | KEY                                     | MODE |                                                       

+------------------+----------------+-----------------------------------------+------+                                                       

|                0 |              6 | 000000010680000015                      | X    |                                                       

|                0 |              6 | 000000010680000014                      | X    |                                                       

|                0 |              6 | 000000010680000014                      | X    |                                                       

|                0 |              6 | 000000010680000013                      | X    |                                                       

|                0 |              6 | 000000010680000013                      | X    |                                                       

|                0 |              6 | 000000010680000012                      | X    |                                                       

|                0 |              6 | 000000010680000012                      | X    |                                                       

|                0 |              6 | 000000010680000011                      | X    |                                                       

|                0 |              6 | 000000010680000011                      | X    |                                                       

|                0 |              6 | 000000010680000010                      | X    |                                                       

|                0 |              6 | 000000010680000010                      | X    |                                                       

|                0 |              6 | 00000001068000000f                      | X    |                                                       

|                0 |              6 | 00000001068000000f                      | X    |                                                       

|                0 |              6 | 00000001068000000e                      | X    |                                                       

|                0 |              6 | 00000001068000000e                      | X    |                                                       

|                0 |              6 | 00000001068000000d                      | X    |

|                0 |              6 | 00000001068000000d                      | X    |

|                0 |              6 | 00000001068000000c                      | X    |

|                0 |              6 | 00000001068000000c                      | X    |

|                0 |              6 | 00000001068000000b                      | X    |

|                0 |              6 | 00000001068000000b                      | X    |

|                0 |              6 | 00000001068000000a                      | X    |

|                0 |              6 | 00000001068000000a                      | X    |

|                0 |              6 | 00000001068000000a - 010000010680000014 | X    |

+------------------+----------------+-----------------------------------------+------+