mysql source code learning

问题探索

一条SQL的生命周期

参考文章

mysql插件化架构

mysql8.0取消查询缓存

官方说明

网络IO模型

参考文章

其他

mysql8.0.24源码编译安装

主要是参考这篇文章，操作过程中根据报错进行fix，特别是修改my.cnf配置文件。

编译安装问题

OpenSSL 版本不兼容
不兼容1.1版本，需要openssl1.0.2，通过yum install openssl-devel。
磁盘空间不足
60g磁盘满了，导致make 终止，/data目录删掉即可。

fatal error: error writing to /tmp/ccFtecZv.s: No space left on device

内存不足
需要开启swap分区

g++: internal compiler error: Killed (program cc1plus)

太吃内存，make巨慢
没找到解决方案…
缺少依赖组件
可能是缺少ncurses-devel

yum install ncurses-devel libaio bison zlib-devel openssl openssl-devel patch

mysqld启动问题

磁盘空间不足

注意my.cnf配置文件，特别innodb参数配置，可能因系统内存或磁盘容量导致启动失败

查看系统磁盘: df -h
[InnoDB] Error number 28 means ‘No space left on device’

vscode本地调试mysql8.0.24

先在云服务器上执行以下命令：

./mysqld --initialize --user=mysql --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data

launch.json配置文件如下：

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{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "debug mysql",
            "type": "cppdbg",
            "request": "launch",
            "program": "/usr/local/mysql/bin/mysqld",
            "args": ["--defaults-file=/usr/local/mysql/etc/my.cnf"],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}",
            "environment": [],
            "externalConsole": false
        }
    ]
}

源码结构

安装tree工具，执行tree -d -L 1命令：

|-- build
|-- client
|-- cmake
|-- components
|-- Docs
|-- doxygen_resources
|-- extra
|-- include
|-- libbinlogevents
|-- libbinlogstandalone
|-- libmysql
|-- libservices
|-- man
|-- mysql-test
|-- mysys
|-- packaging
|-- plugin
|-- router
|-- scripts
|-- share
|-- source_downloads
|-- sql
|-- sql-common
|-- storage
|-- strings
|-- support-files
|-- testclients
|-- unittest
|-- utilities
`-- vio

语雀代码画时序图： https://www.bookstack.cn/read/yuque/34.md

Mysql线程的基本设置

mysql> show variables like 'thread%';
+-------------------+---------------------------+
| Variable_name     | Value                     |
+-------------------+---------------------------+
| thread_cache_size | 1536                      |
| thread_handling   | one-thread-per-connection |
| thread_stack      | 524288                    |
+-------------------+---------------------------+
3 rows in set (0.05 sec)
mysql> show global status like 'Thread%';
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| Threads_cached    | 0     |
| Threads_connected | 1     |
| Threads_created   | 1     |
| Threads_running   | 1     |
+-------------------+-------+
4 rows in set (0.07 sec)

远程连接

root忘记密码

--- mysqld模块下增加skip-grant-tables配置,免密登录后执行以下命令：
update user set authentication_string = '' where user ='root';
--- 注释掉skip-grant-tables配置,重新登录，设置新密码：
ALTER USER 'root'@'localhost' IDENTIFIED BY 'root123456';

允许外部访问

use mysql;
update user set host='%' where user ='root';
FLUSH PRIVILEGES;