mysql主从搭建

环境：ubuntu20.04.1，mysql：8.0.22。
主：192.168.87.3
备：192.168.87.6

安装数据库

sudo apt-get install mysql-server
sudo apt-get install mysql-client
sudo apt-get install libmysqlclient-dev

数据库配置

设置数据库密码

首次安装后，使用sudo mysql -uroot -p直接进入，更改root密码操作如下：

use mysql；
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'root';
FLUSH PRIVILEGES;

主库设置

配置/etc/mysql/mysql.conf.d/mysqld.cnf如下：

[mysqld]

user		= mysql
pid-file	= /var/run/mysqld/mysqld.pid
socket	= /var/run/mysqld/mysqld.sock
port		= 3306
datadir	= /var/lib/mysql


bind-address		= 192.168.87.3 # 本机ip
mysqlx-bind-address	= 127.0.0.1


key_buffer_size		= 16M

myisam-recover-options  = BACKUP

max_connections        = 1000

log_error = /var/log/mysql/error.log

server-id		= 1
log_bin			= /var/log/mysql/mysql-bin.log
max_binlog_size   = 100M
binlog_do_db          = test
binlog_ignore_db      = mysql
binlog_format = row
sync_binlog = 1
innodb_flush_log_at_trx_commit = 1

更改完后重启数据库
```
systemctl restart mysql.service
```

创建同步账号

CREATE USER 'sync'@'192.168.87.6' IDENTIFIED WITH mysql_native_password BY 'sync';
grant replication slave on *.* to 'sync'@'192.168.87.6';

192.168.87.6为从数据库的IP。

查看配置是否生效
创建数据快照
```
mysqldump --all-databases --master-data > dbdump.db
```
–master-data这个选项会自动加上CHANGE_MASTER_TO给从机来开始复制过程。在备份时使用–databases(备份特定的数据库)和–ignore-tables(排除备份特定的表) 选项，各个数据库和表名之间用空格隔开。

设置远程访问

use mysql;
update user set host='%' where user = 'root';
FLUSH PRIVILEGES;
GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;

如果此时仍无法访问，查看防火墙是否关闭。关闭命令：

sudo ufw disable

或者开放3306端口号。

从数据库配置

配置/etc/mysql/mysql.conf.d/mysqld.cnf如下：

[mysqld]

user		= mysql
pid-file	= /var/run/mysqld/mysqld.pid
socket	= /var/run/mysqld/mysqld.sock
port		= 3306
datadir	= /var/lib/mysql

bind-address		= 192.168.87.6
mysqlx-bind-address	= 127.0.0.1
key_buffer_size		= 16M

myisam-recover-options  = BACKUP

log_error = /var/log/mysql/error.log

server-id		= 2
log_bin			= /var/log/mysql/mysql-bin.log
# binlog_expire_logs_seconds	= 2592000
max_binlog_size   = 100M
binlog_do_db		= test
binlog_ignore_db	= mysql

同步数据

在主库上dump的文件scp到从库上，然后登录mysql并执行如下命令：
```
set sql_log_bin=0;
source /home/shitianming/Documents/dbdump.db
```

配置slave

CHANGE MASTER TO
MASTER_HOST='192.168.87.3',
MASTER_USER='sync',
MASTER_PASSWORD='sync',
MASTER_PORT=3306,
MASTER_LOG_FILE='mysql-bin.000003',
MASTER_LOG_POS=730;