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//创建语句如下:
CREATE TABLE `t_test2` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
`addr` varchar(30) DEFAULT NULL,
`email` varchar(30) DEFAULT NULL,
`note` varchar(3000) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `id` (`id`),
KEY `name_index` (`name`)
)ENGINE=InnoDB AUTO_INCREMENT=1094469 DEFAULT CHARSET=utf8
mysql> select count(id) from t_test;
+-----------+
| count(id) |
+-----------+
| 1013432 |
+-----------+
1 row in set (53.38 sec)
mysql> select count(name) from t_test;
+-------------+
| count(name) |
+-------------+
| 1013432 |
+-------------+
1 row in set (11.67 sec)
CREATE TABLE `t_test` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(30) DEFAULT NULL,
`addr` varchar(30) DEFAULT NULL,
`email` varchar(30) DEFAULT NULL,
`note` varchar(3000) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `name_index` (`name`)
) ENGINE=InnoDB AUTO_INCREMENT=1094469 DEFAULT CHARSET=utf8
mysql> SELECT SQL_NO_CACHE count(id) from t_test;
+-----------+
| count(id) |
+-----------+
| 1013432 |
+-----------+
1 row in set (46.73 sec)
mysql> SELECT SQL_NO_CACHE count(name) from t_test;
+-------------+
| count(name) |
+-------------+
| 1013432 |
+-------------+
1 row in set (11.56 sec)
mysql> select count(name) from t_test;
+-------------+
| count(name) |
+-------------+
| 1013432 |
+-------------+
1 row in set (35.84 sec)
mysql> select count(id) from t_test;
+-----------+
| count(id) |
+-----------+
| 1013432 |
+-----------+
1 row in set (56.22 sec)
mysql> select count(name) from t_test;
+-------------+
| count(name) |
+-------------+
| 1013432 |
+-------------+
1 row in set (13.67 sec)
mysql> select count(id) from t_test;
+-----------+
| count(id) |
+-----------+
| 1013432 |
+-----------+
1 row in set (56.70 sec)
mysql> SELECT SQL_NO_CACHE count(name) from t_test;
+-------------+
| count(name) |
+-------------+
| 1013432 |
+-------------+
1 row in set (1.84 sec)
mysql> SELECT SQL_NO_CACHE count(id) from t_test;
+-----------+
| count(id) |
+-----------+
| 1013432 |
+-----------+
1 row in set (0.00 sec)