Mysql RR隔离更新列没有索引 会锁全表

<pre name="code" class="html">mysql> show variables like '%tx_isolation%';
+---------------+-----------------+
| Variable_name | Value           |
+---------------+-----------------+
| tx_isolation  | REPEATABLE-READ |
+---------------+-----------------+
1 row in set (0.00 sec)

Session 1:
mysql> show index from test;
Empty set (0.00 sec)

mysql> update test set name='xxxx' where id=2;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 0

Session 2:
mysql> select * from test;
+------+------+
| id   | name |
+------+------+
|    1 | b    |
|   11 | aa   |
|    2 | xxxx |
|   10 | a    |
+------+------+
4 rows in set (0.00 sec)

mysql>  update test set name='xxxx' where id=10;
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction

没有索引的情况 ,RR隔离级别 是锁全表

//*********************************************************************

Session 1:
mysql> update test set id=99 where id=1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Session 2:
mysql> update test set id=100 where id=2; --HANG

//测试有主键的情况下:

mysql> CREATE TABLE `s100` (
    ->   `sn` int(11) NOT NULL AUTO_INCREMENT,
    ->   `id` int,
    ->   `info` varchar(40) DEFAULT NULL,
    ->   PRIMARY KEY (`sn`)
    -> ) ENGINE=InnoDB AUTO_INCREMENT=225 DEFAULT CHARSET=utf8 ;
Query OK, 0 rows affected (0.04 sec)

mysql> show index from s100;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| s100  |          0 | PRIMARY  |            1 | sn          | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
1 row in set (0.00 sec)

Session 1：

mysql> update s100 set id=100 where id=1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

Session 2:

mysql> update s100 set id=200 where id=2;---Hang

//测试更新是否锁全表:

mysql> explain update Product set
    ->                 status = '3'
    ->                 where status = '2' and buyToTime < '2016-05-10 12:54:00';
+----+-------------+---------+-------+---------------+---------+---------+------+------+-------------+
| id | select_type | table   | type  | possible_keys | key     | key_len | ref  | rows | Extra       |
+----+-------------+---------+-------+---------------+---------+---------+------+------+-------------+
|  1 | SIMPLE      | Product | index | NULL          | PRIMARY | 4       | NULL |  506 | Using where |
+----+-------------+---------+-------+---------------+---------+---------+------+------+-------------+
1 row in set (0.00 sec)

从possible_keys中所选择使用的索引

正常走索引的更新是:

mysql> explain update test set id=100 where id=1;
+----+-------------+-------+-------+---------------+-----------+---------+-------+------+------------------------------+
| id | select_type | table | type  | possible_keys | key       | key_len | ref   | rows | Extra                        |
+----+-------------+-------+-------+---------------+-----------+---------+-------+------+------------------------------+
|  1 | SIMPLE      | test  | range | test_idx1     | test_idx1 | 5       | const |    1 | Using where; Using temporary |
+----+-------------+-------+-------+---------------+-----------+---------+-------+------+------------------------------+
1 row in set (0.00 sec)