why caused LOCK by select query in mysql cluster?

[Lee Wonseok]

hello.

I am using Mysql Cluster 5.1.23.rc.

I firstly runned below select query.
(of course, none transaction)

SELECT t.id, s.id FROM t, s
WHERE t.obj_id = s.obj_id AND
login = '[e-mail]';

(this query takes time 2 min.)

then, i immediately runned below update query.

update t set status=5 where obj_id=33333;

then, update query is locked.
below is show processlist result.

mysql> show processlist;

| 663 | user1 | host-10.10.internal:2841 | test | Query | 35 | Sending data | SELECT t.id, s.id FROM t, s WHERE t.obj_id = s.obj_id AND login = '[e-mail]'; |
| 664 | user2 | host-10.10.internal:2842 | test | Query | 5 | Locked | update t set status=5 where obj_id=33333; |

this is normal operation of mysql cluster???