通常应用需要对表中的数据进行翻页，如果数据量很大，往往会带来性能上的问题：
root@sns 07:16:25>select count(*) from reply_0004 where thread_id = 5616385 and deleted = 0;
+———-+
| count(*) |
+———-+
| 1236795 |
+———-+
1 row in set (0.44 sec)
root@sns 07:16:30>select id
from reply_0004 where thread_id = 5616385 and deleted = 0
order by id
