当前位置:网站首页>MySQL数据库索引教程(超详细)
MySQL数据库索引教程(超详细)
2022-07-05 18:33:00 【InfoQ】
索引初步
缺点
索引结构
实验准备(以下实验都在VMware中进行)
1、新建一个数据库
create database test default character set utf8;
2、新建一个数据表
CREATE TABLE testsql (
id int NOT NULL AUTO_INCREMENT PRIMARY KEY comment '自增主键',
dept tinyint not null comment '部门id',
name varchar(30) comment '用户名称',
create_time datetime not null comment '注册时间',
last_login_time datetime comment '最后登录时间'
) comment '测试表';
3、写入数据
insert into testsql values(1,1,'user_1', '2018-01-01 00:00:00', '2018-03-01 12:00:00');
4、赋值
set @i=1;
5、做一个表的倍数增加(不然几千万的数据写一年都写不完)
insert into testsql(dept, name, create_time, last_login_time)
select left(rand()*10,1) as dept, #随机生成1~10的整数
concat('user_',@i:[email protected]+1), #按序列生成不同的name
date_add(create_time,interval [email protected]*cast(rand()*100 as signed) SECOND), #生成有时间大顺序随机注册时间
date_add(date_add(create_time,interval [email protected]*cast(rand()*100 as signed) SECOND), interval + cast(rand()*1000000 as signed) SECOND) #生成有时间大顺序的随机的最后登录时间
from testsql;
6、查看
select count(*) from testsql;
show variables like "%_buffer%";
7、实验
select COUNT(*) from t where name='user_500000';
8、创建索引
9、实验效果
select COUNT(*) from t where name='user_500000';
边栏推荐
- 彻底理解为什么网络 I/O 会被阻塞?
- How to write good code defensive programming
- Whether to take a duplicate subset with duplicate elements [how to take a subset? How to remove duplicates?]
- The easycvr platform reports an error "ID cannot be empty" through the interface editing channel. What is the reason?
- 【pm2详解】
- 开户注册挖财安全吗?有没有风险的?靠谱吗?
- Use of websocket tool
- 中文版Postman?功能真心强大!
- 【Autosar 十四 启动流程详解】
- Copy the linked list with random pointer in the "Li Kou brush question plan"
猜你喜欢
Tupu software digital twin | visual management system based on BIM Technology
Find in MySQL_ in_ Detailed explanation of set() function usage
Thoroughly understand why network i/o is blocked?
Isprs2020/ cloud detection: transferring deep learning models for cloud detection between landsat-8 and proba-v
Share: ZTE Yuanhang 30 Pro root unlock BL magick ZTE 7532n 8040n 9041n brush mask original brush package root method Download
AI金榜题名时,MLPerf榜单的份量究竟有多重?
The 10th global Cloud Computing Conference | Huayun data won the "special contribution award for the 10th anniversary of 2013-2022"
Reading notes of Clickhouse principle analysis and Application Practice (5)
AI表现越差,获得奖金越高?纽约大学博士拿出百万重金,悬赏让大模型表现差劲的任务
Fix vulnerability - mysql, ES
随机推荐
All you want to know about clothing ERP is here
Linear table - abstract data type
关于服装ERP,你想知道的都在这里了
Is it safe for Apple mobile phone to speculate in stocks? Is it a fraud to get new debts?
Trust counts the number of occurrences of words in the file
[use electron to develop desktop on youqilin]
Use QT to traverse JSON documents and search sub objects
IDEA配置npm启动
Sibling components carry out value transfer (there is a sequence displayed)
开户注册挖财安全吗?有没有风险的?靠谱吗?
Simple query cost estimation
The origin of PTS, DTS and duration of audio and video packages
LeetCode 6109. Number of people who know the secret
怎么自动安装pythn三方库
ViewPager + RecyclerView的内存泄漏
The 2022 China Xinchuang Ecological Market Research and model selection evaluation report released that Huayun data was selected as the mainstream manufacturer of Xinchuang IT infrastructure!
文章中的逻辑词
ICML2022 | 长尾识别中分布外检测的部分和非对称对比学习
案例分享|金融业数据运营运维一体化建设
Cronab log: how to record the output of my cron script