奇怪的区间锁问题

Session 1:
mysql> select * from t1;
+-----+------+------+
| sn  | id   | info |
+-----+------+------+
| 235 |    1 | a1   |
| 236 |    2 | a2   |
| 237 |    3 | a3   |
| 238 |    4 | a4   |
| 239 |    5 | a5   |
| 240 |    6 | a6   |
| 241 |    7 | a7   |
| 242 |    8 | a8   |
| 243 |    9 | a9   |
| 244 |   10 | a10  |
| 245 |   15 | a15  |
+-----+------+------+
11 rows in set (0.00 sec)

mysql> show index from t1;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| t1    |          0 | PRIMARY  |            1 | sn          | A         |          11 |     NULL | NULL   |      | BTREE      |         |               |
| t1    |          1 | t1_idx1  |            1 | id          | A         |          11 |     NULL | NULL   | YES  | BTREE      |         |               |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)

Session 2:
Database changed
mysql> update t1 set id=400 where id=4;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> rollback;
Query OK, 0 rows affected (0.01 sec)

mysql> update t1 set id=500 where id=5;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=600 where id=6;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=700 where id=7;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=800 where id=8;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=900 where id=9;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

/******把t1_idx1  换成unique index  继续测试:

Session 1:

mysql> create unique index t1_idx1 on t1(id);
Query OK, 0 rows affected (0.04 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql>
mysql>
mysql> show index from t1;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| t1    |          0 | PRIMARY  |            1 | sn          | A         |          11 |     NULL | NULL   |      | BTREE      |         |               |
| t1    |          0 | t1_idx1  |            1 | id          | A         |          11 |     NULL | NULL   | YES  | BTREE      |         |               |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
2 rows in set (0.00 sec)

mysql>  select * from t1 where id BETWEEN 5 and 7 for update;
+-----+------+------+
| sn  | id   | info |
+-----+------+------+
| 239 |    5 | a5   |
| 240 |    6 | a6   |
| 241 |    7 | a7   |
+-----+------+------+
3 rows in set (0.00 sec)

Session 2:

mysql> update t1 set id=400 where id=4;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> rollback;
Query OK, 0 rows affected (0.01 sec)

mysql> update t1 set id=500 where id=5;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=600 where id=6;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=700 where id=7;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=800 where id=8;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
mysql> update t1 set id=900 where id=9;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

创建唯一锁 仍旧锁住了5，6,7,8 4条记录