Msyql 主从同步

文章目录

• 前言
• 搭建
• • 主库
  • 从库
• 测试
• • 主库
  • 从库
• 问题
• • 是推还是拉
  • 链接断了怎么办
  • 复制策略有哪些

前言

为什么要进行主从复制呢？

• 数据备份
• 读写分离，减轻主库压力

搭建

主库

• 准备mysql安装包

    mysql-8.0.26.tar.gz

• 解压安装包

  tar -zxvf mysql-8.0.26.tar.gz

• 添加环境变量

  编辑环境变量文件

  sudo vim /etc/profile

  #在末尾添加内容
  export MYSQL_HOME=/softwares/mysql-8.0.26/
  export PATH=PATH:MYSQL_HOME/bin

  #将环境变量生效
  source /etc/profile

• 创建文件夹

  sudo mkdir -p /softwares/mysql-8.0.26/data
  sudo mkdir -p /softwares/mysql-8.0.26/binlog

• 创建用户

  sudo groupadd mysql
  sudo useradd -g mysql mysql
  sudo chown -R mysql:mysql /softwares/mysql-8.0.26

• 修改my.cnf 配置文件

  [mysqld]
  basedir=/softwares/mysql-8.0.26
  datadir=/softwares/mysql-8.0.26/data
  socket=/softwares/mysql-8.0.26/mysql.sock
  log-error=/softwares/mysql-8.0.26/mysqld.log
  symbolic-links=0
  secure_file_priv=''
  server-id=2 # 服务id，必填，且跟从库不一样
  log-bin=/softwares/mysql-8.0.26/binlog/mysql-bin
  binlog-ignore-db=mysql # 忽略需要记录的数据库
  binlog-do-db=test_db # 指定需要记录的数据库

  [mysqld_safe]
  log-error=/softwares/mysql-8.0.26/mysqld.log
  pid-file=/softwares/mysql-8.0.26/mysqld.pid

  [client]
  port=3306
  socket=/softwares/mysql-8.0.26/mysql.sock

• 初始化数据库

  sudo su - root -c '/softwares/mysql-8.0.26/bin/mysqld --initialize --user=mysql --basedir=/softwares/mysql-8.0.26/ --datadir=/softwares/mysql-8.0.26/data/'

• 启动服务

  sudo su - mysql -c '/softwares/mysql-8.0.26/bin/mysqld_safe --user=mysql &'

• 查看并修改初始密码

  查看初始密码

  sudo cat /softwares/mysql-8.0.26/mysqld.log |grep "temporary password" |awk -F "root@localhost: " '{print $2}'

  登录，输入上一步获取的密码

  mysql -uroot -p

  修改密码

  mysql> alter user root@localhost identified by 'Bigdata_123';
  mysql> create user 'root'@'%' identified by 'Bigdata_123';
  mysql> GRANT ALL PRIVILEGES on . to 'root'@'%';
  mysql> GRANT ALL PRIVILEGES on . to 'root'@'localhost';
  mysql> flush privileges;

从库

与主库基本一致，主要在my.cnf 上有一点不一样

[mysqld]
basedir=/softwares/mysql-8.0.26
datadir=/softwares/mysql-8.0.26/data
socket=/softwares/mysql-8.0.26/mysql.sock
log-error=/softwares/mysql-8.0.26/mysqld.log
symbolic-links=0 
secure_file_priv=''
server-id=9 # 与主库不一致
replicate-do-db=test_db # 需要同步的数据库
replicate-ignore-db=mysql # 不需要同步的数据库
sync_binlog=1
slave-net-timeout=60 # 当收不到master数据时，重新发起连接，时间默认是60s


[mysqld_safe]
log-error=/softwares/mysql-8.0.26/mysqld.log
pid-file=/softwares/mysql-8.0.26/mysqld.pid 


[client]
port=3306
socket=/softwares/mysql-8.0.26/mysql.sock

测试

主库

• 准备数据库

  创建数据库

  create database test_db character set utf8;

  选择数据库

  use test_db;

  创建表

  CREATE TABLE grade(
  gradeid INT(10) PRIMARY KEY AUTO_INCREMENT,
  gradename VARCHAR(50) NOT NULL
  );

  插入数据

  insert into grade (GradeID,GradeName) values (1,'大一'),(2,'大二'),(3,'大三'),(4,'大四');

  查看数据

  select * from grade

• dump数据

  mysqldump -uroot -pBigdata_123 -h127.0.0.1 --all-databases --single-transaction --routines --events --triggers --master-data=2 --hex-blob --default-character-set=utf8mb4 --flush-logs --quick > all.sql

• 查看当前binlog信息

  mysql> show master status\G;
  *************************** 1. row ***************************
  File: mysql-bin.000005
  Position: 156
  Binlog_Do_DB:
  Binlog_Ignore_DB: mysql
  Executed_Gtid_Set:
  1 row in set (0.00 sec)

• 复制all.sql数据到从库，目标文件夹是/tmp

  scp all.sql root@slave:/tmp/

从库

• 恢复dump数据

  登录数据库

  mysql -uroot -pBigdata_!23

  导入sql数据

  source /tmp/all.sql

• 连接主库

  登录客户端，通过该方式可避免复制时的错误

  mysql -uroot -pBigdata_123 -h slave1 -P3306 --get-server-public-key

  错误信息：

  Last_IO_Errno:2061
  Last_IO_Error:error connecting to mater 'root@master:3306' - retry-time:60 retries:1 massage:Authentication plugin 'caching_sha2_password' reported error:Authentication require secure connection.

  停止同步

  stop slave

  连接到主库

  change master to master_host="master",master_user="root",master_password="Bigdata_123",master_log_file="mysql-bin.000005" ,master_log_pos=156;

  开启同步

  start slave

• 查看同步信息

  mysql> show slave status\G;
  *************************** 1. row ***************************
  Slave_IO_State: Waiting for source to send event
  Master_Host: master
  Master_User: root
  Master_Port: 3306
  Connect_Retry: 60
  Master_Log_File: mysql-bin.000005
  Read_Master_Log_Pos: 156
  Relay_Log_File: slave1-relay-bin.000006
  Relay_Log_Pos: 371
  Relay_Master_Log_File: mysql-bin.000005
  Slave_IO_Running: Yes
  Slave_SQL_Running: Yes
  Replicate_Do_DB: test_db
  Replicate_Ignore_DB: mysql
  Replicate_Do_Table:
  Replicate_Ignore_Table:
  Replicate_Wild_Do_Table:
  Replicate_Wild_Ignore_Table:
  Last_Errno: 0
  Last_Error:
  Skip_Counter: 0
  Exec_Master_Log_Pos: 156
  Relay_Log_Space: 628
  Until_Condition: None
  Until_Log_File:
  Until_Log_Pos: 0
  Master_SSL_Allowed: No
  Master_SSL_CA_File:
  Master_SSL_CA_Path:
  Master_SSL_Cert:
  Master_SSL_Cipher:
  Master_SSL_Key:
  Seconds_Behind_Master: 0
  Master_SSL_Verify_Server_Cert: No
  Last_IO_Errno: 0
  Last_IO_Error:
  Last_SQL_Errno: 0
  Last_SQL_Error:
  Replicate_Ignore_Server_Ids:
  Master_Server_Id: 2
  Master_UUID: 7ff3e0e4-584f-11ef-baa2-0242ac110013
  Master_Info_File: mysql.slave_master_info
  SQL_Delay: 0
  SQL_Remaining_Delay: NULL
  Slave_SQL_Running_State: Replica has read all relay log; waiting for more updates
  Master_Retry_Count: 86400
  Master_Bind:
  Last_IO_Error_Timestamp:
  Last_SQL_Error_Timestamp:
  Master_SSL_Crl:
  Master_SSL_Crlpath:
  Retrieved_Gtid_Set:
  Executed_Gtid_Set:
  Auto_Position: 0
  Replicate_Rewrite_DB:
  Channel_Name:
  Master_TLS_Version:
  Master_public_key_path:
  Get_master_public_key: 0
  Network_Namespace:
  1 row in set, 1 warning (0.01 sec)

问题

是推还是拉

slave先主动去拉，发送binlog文件名和pos位置，master推送该位置之后的数据，
同时建立好长链接，当master有数据更新时，推送给slave

链接断了怎么办

slave会主动重新建立连接，超时时间默认60s，可配置

复制策略有哪些

• 异步复制
  效率上相对最高，也是mysql默认方式，master只管写入binlog就返回
• 半同步复制
  等到有一个salve返回同步成功后，master再响应，需要安装插件来实现
• 同步复制
  等全部salve返回成功后，master再响应，需要安装插件来实现