MySQL 联合索引测试

搭建测试环境

1：创建表

CREATE TABLE tab_index

(id int(5),

age int(3),

dte datetime);

2：插入测试数据

INSERT INTO tab_index

VALUES(1,'2012-05-13',23);

INSERT INTO tab_index

VALUES(2,'2012-05-13',23);

INSERT INTO tab_index

VALUES(3,'2012-05-13',31);

INSERT INTO tab_index

VALUES(4,'2012-05-13',32);

INSERT INTO tab_index

VALUES(5,'2012-05-13',33);

INSERT INTO tab_index

VALUES(6,'2012-06-13',34);

INSERT INTO tab_index

VALUES(7,'2012-07-13',35);

INSERT INTO tab_index

VALUES(8,'2012-08-13',36);

INSERT INTO tab_index

VALUES(9,'2012-09-13',37);

INSERT INTO tab_index

VALUES(10,'2012-05-17',38);

INSERT INTO tab_index

VALUES(11,'2012-05-19',39);

INSERT INTO tab_index

VALUES(1,'2012-05-13',23);

INSERT INTO tab_index

VALUES(2,'2012-05-13',23);

INSERT INTO tab_index

VALUES(3,'2012-05-13',31);

INSERT INTO tab_index

VALUES(4,'2012-05-13',32);

INSERT INTO tab_index

VALUES(5,'2012-05-13',33);

INSERT INTO tab_index

VALUES(6,'2012-06-13',34);

INSERT INTO tab_index

VALUES(7,'2012-07-13',35);

INSERT INTO tab_index

VALUES(8,'2012-08-13',36);

INSERT INTO tab_index

VALUES(9,'2012-09-13',37);

INSERT INTO tab_index

VALUES(10,'2012-05-17',38);

INSERT INTO tab_index

VALUES(11,'2012-05-19',39);

INSERT INTO tab_index

VALUES(1,'2012-05-13',23);

INSERT INTO tab_index

VALUES(2,'2015-05-13',23);

INSERT INTO tab_index

VALUES(3,'2012-05-13',31);

INSERT INTO tab_index

VALUES(4,'2012-05-13',32);

INSERT INTO tab_index

VALUES(5,'2012-05-13',33);

INSERT INTO tab_index

VALUES(6,'2012-06-13',34);

INSERT INTO tab_index

VALUES(7,'2013-07-13',35);

INSERT INTO tab_index

VALUES(8,'2012-08-13',36);

INSERT INTO tab_index

VALUES(9,'2012-09-13',37);

INSERT INTO tab_index

VALUES(10,'2012-05-17',38);

INSERT INTO tab_index

VALUES(11,'2011-05-19',39);

INSERT INTO tab_index

VALUES(1,'2012-05-13',23);

INSERT INTO tab_index

VALUES(2,'2012-05-13',23);

INSERT INTO tab_index

VALUES(3,'2010-05-13',31);

INSERT INTO tab_index

VALUES(4,'2012-05-13',32);

INSERT INTO tab_index

VALUES(5,'2010-05-13',33);

INSERT INTO tab_index

VALUES(6,'2010-06-13',34);

INSERT INTO tab_index

VALUES(7,'2012-07-13',35);

INSERT INTO tab_index

VALUES(8,'2012-08-13',36);

INSERT INTO tab_index

VALUES(9,'2011-09-13',37);

INSERT INTO tab_index

VALUES(10,'2012-05-17',38);

INSERT INTO tab_index

VALUES(11,'2012-05-19',39);

INSERT INTO tab_index

VALUES(1,'2012-05-13',23);

INSERT INTO tab_index

VALUES(2,'2012-05-13',23);

INSERT INTO tab_index

VALUES(3,'2012-05-13',31);

INSERT INTO tab_index

VALUES(4,'2012-05-13',32);

INSERT INTO tab_index

VALUES(5,'2012-05-13',33);

INSERT INTO tab_index

VALUES(6,'2012-06-13',34);

INSERT INTO tab_index

VALUES(7,'2014-07-13',35);

INSERT INTO tab_index

VALUES(8,'2012-08-13',36);

INSERT INTO tab_index

VALUES(9,'2011-09-13',37);

INSERT INTO tab_index

VALUES(10,'2012-05-17',38);

INSERT INTO tab_index

VALUES(11,'2012-05-19',39);

3：创建id和age上的联合索引

CREATE INDEX idx1

ON tab_index(id,age);

4：开始测试

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE id=3;

+----+-------------+-----------+------+---------------+------+---------+-------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref   | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 5       | const |    5 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------+------+-------------+

1 row in set (0.00 sec)

 id=3走索引,age=31不走索引。很容易理解

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE age=31;

+----+-------------+-----------+------+---------------+------+---------+------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref  | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+------+------+-------------+

|  1 | SIMPLE      | tab_index | ALL  | NULL          | NULL | NULL    | NULL |   55 | Using where |

+----+-------------+-----------+------+---------------+------+---------+------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE id=3 AND age=31;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

　id=3 AND age=31 和 age=31 AND id=3都走索引了，但是索引长度跟之前不同

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE age=31 AND id=3 ;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE id=3 AND age=31 AND dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00';

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE id=3 AND dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00' AND age=31;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00' AND id=3 AND age=31;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE age=31 AND id=3 AND dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00';

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE age=31 AND dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00' AND id=3 ;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

mysql> EXPLAIN SELECT id,dte,age

    -> FROM tab_index

    -> WHERE dte BETWEEN '2011-05-13 00:00:00' AND '2013-05-13 00:00:00' AND age=31 AND id=3 ;

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

| id | select_type | table     | type | possible_keys | key  | key_len | ref         | rows | Extra       |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

|  1 | SIMPLE      | tab_index | ref  | idx1          | idx1 | 10      | const,const |    1 | Using where |

+----+-------------+-----------+------+---------------+------+---------+-------------+------+-------------+

1 row in set (0.00 sec)

另外其他几种情况，同学们自己尝试下以加深印象。

总结如下：

(id)走索引，且索引长度最短
(id,dte)走索引，且索引长度最短

(id,age)走索引，且索引长度最长
(id,age,dte)走索引，且索引长度最长
(id,dte,age)走索引，且索引长度最长
(dte,id,age)走索引，且索引长度最长
(dte,age,id)走索引，且索引长度最长
(age,dte,id)走索引，且索引长度最长
(age,id,dte)走索引，且索引长度最长

MySQL 联合索引测试的更多相关文章

MySQL 联合索引测试2
接上一篇文章: http://www.cnblogs.com/xiaoit/p/4430300.html 1:首先删掉上一篇建立的索引,重新建立一个. mysql> DROP INDEX idx ...
MySQL 联合索引测试3
接上一篇文章: http://www.cnblogs.com/xiaoit/p/4430387.html 有时候会出现某字段建立一个索引,但是查看执行计划的时候发现还是全扫了表? 可以强制走下索引看看 ...
SQL Server中的联合主键、聚集索引、非聚集索引、mysql 联合索引
我们都知道在一个表中当需要2列以上才能确定记录的唯一性的时候,就需要用到联合主键,当建立联合主键以后,在查询数据的时候性能就会有很大的提升,不过并不是对联合主键的任何列单独查询的时候性能都会提升,但我 ...
三道MySQL联合索引面试题，淘汰80%的面试者，你能答对几道
众所周知MySQL联合索引遵循最左前缀匹配原则,在少数情况下也会不遵循(有兴趣,可以翻一下上篇文章). 创建联合索引的时候,建议优先把区分度高的字段放在第一列. 至于怎么统计区分度,可以按照下面这种方 ...
MySQL 联合索引详解
MySQL 联合索引详解联合索引又叫复合索引.对于复合索引:Mysql从左到右的使用索引中的字段,一个查询可以只使用索引中的一部份,但只能是最左侧部分.例如索引是key index (a,b,c ...
mysql 联合索引(转)
http://blog.csdn.net/lmh12506/article/details/8879916 mysql 联合索引详解联合索引又叫复合索引.对于复合索引:Mysql从左到右的使用索引中 ...
MySQL联合索引VS单列索引
MySQL联合索引VS单列索引以一个一千万数据量的表格为例 1. 建表建索引 USE foo; DROP TABLE IF EXISTS tmp; CREATE TABLE tmp ( id INT ...
MySQL联合索引最左匹配范例
MySQL联合索引最左匹配范例参考文章:http://blog.jobbole.com/24006/ 创建示例表. 示例表来自MySQL官方文档: https://dev.mysql.com/doc ...
[转]mysql联合索引
mysql联合索引命名规则:表名_字段名1.需要加索引的字段,要在where条件中2.数据量少的字段不需要加索引3.如果where条件中是OR关系,加索引不起作用4.符合最左原则 https:/ ...

随机推荐

WordPress 客户端软件列表
Windows: BlogDesk BlogJet Blog Writer Chrysanth WebStory Deepest Sender (Firefox或SeaMonkey扩展,跨平台- De ...
Go 收藏
Golang 定位解决分布式系统,服务器应用开发,主要竞争对手是 Java.Python 之类:Rust 定位解决单机安全问题,高性能场景偏系统底层开发,主要竞争对手就是 C 和 C++. Golan ...
03把IL编译成可执行文件
1.在记事本中编写IL代码如下: .assembly HelloWorld{} .assembly extern mscorlib{} .method public static void Mai ...
datagrid在MVC中的运用04-同时添加搜索和操作区域
本文介绍在datagrid上同时添加搜索和操作区域. 仅仅是增加操作区域 □ 方法1 $('#dg').datagrid({ toolbar: '#tb' }); <div id="t ...
Windows 8 Metro 应用开发入门(一)：开发环境介绍
摘要 Windows8已经发布,随之而来的基于WinRT的Metro应用也正向我们走来,正像它所宣传的:光滑.快.现代.看习惯了玻璃.立体风格的应用,或许Metro的简洁能给你留下不一样的体验.Vi ...
修改Eclipse/MyEclipse项目的默认编码
应该是中文操作系统的原因,eclipse默认的新项目的编码是GBK,出于对编码支持的考虑,项目组中最好统一要求是UTF-8编码进行开发. 修改eclipse的配置,可以使得eclipse的新建项目的默 ...
利用nginx加速web访问
起因---------- 在最近新系统的设计中对于首页打开速度的问题做了一些考虑,由于页面上还是以动态数据为主,所以简单的静态化数据可能并不行,所以需要从业务和技术结合的角度去考虑这个问题.由于有些数 ...
Linux下安装Oracle的过程和涉及的知识点-系列6
16.一路安装后.会提示下面界面.此时须要用root登录下面文件夹,然后运行这两个脚本. 至此,Oracle软件的安装就已经完毕了,接下来就能够创建数据库了. 17.选择自己定义数据库: 输入数据库名 ...
《逆袭大学：传给IT学子的正能量》
<逆袭大学:传给IT学子的正能量> 基本信息作者: 贺利坚丛书名: 图灵原创出版社:人民邮电出版社 ISBN:9787115347473 上架时间:2014-3-3 出版日期:201 ...
C语言条件编译
使用与平台有关的C语言函数,可能会使得程序不具有可移植性.比如Socket编程.多线程编程等是与平台有关的. 若想将程序做成平台无关的就需要用到与平台相关的条件编译. 下面转自:http://blog ...

MySQL 联合索引测试

MySQL 联合索引测试的更多相关文章

随机推荐

热门专题