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

BTSync 2.0 Vs. 1.4 Folders
Sync 2.0 supports boths new 2.0 folders and classic 1.4 folders, s o when you upgrade your Sync it w ...
hdu1015 Safecracker (暴力枚举)
http://acm.hdu.edu.cn/showproblem.php?pid=1015 Safecracker Time Limit: 2000/1000 MS (Java/Others) ...
AMD64 Instruction-Level Debugging With dbx
http://www.oracle.com/technetwork/server-storage/solarisstudio/documentation/amd64-dbx-364568.html A ...
java基础学习总结——哈希编码
一.哈希编码
java基础学习总结——网络编程
一.网络基础概念首先理清一个概念:网络编程 != 网站编程,网络编程现在一般称为TCP/IP编程.
Round #169 (Div. 2)C. Little Girl and Maximum Sum
1.用退化的线段树(也就是没有区间查询)做... 2.注意longlong. #include<cstdio> #include<cstring> #include<io ...
javascript级联菜单，数据从数据库中获取
1.html代码: <%@ page contentType="text/html; charset=gb2312" %> <%@ page import=&qu ...
Java Web应用软件保护方法
1 代码混淆概述目前针对Java源文件方法主要有以下几种方法:本地编译技术.数字水印技术.ClassLoader加密技术以及代码混淆技术.Java本地编译是指将Java应用程序编译成本地应用程序,如W ...
numpy转换
csv2npy cccsv=numpy.genfromtxt('/root/c.csv', delimiter = ',') buf2npy imga=numpy.frombuffer(buf,num ...
jenkins error: "no valid crumb was included in the request"
一.问题描述(Problem Description): 在jenkins中创建新任务时候选择“拷贝已存在任务”,点击OK,跳转到下一步时候弹出如下错误信息:"No valid crumb ...

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