mysql主从
目录
1.mysql简介
在现代企业中，数据显得尤为重要，而存储数据的数据库选择又五花八门，但无论是何种数据库，均存在着一种隐患。
想几个问题：
- 用一台数据库存放数据，若此数据库服务器宕机了导致数据丢失怎么办？
- 业务量大了，数据多了，访问的人多了，一台数据库无法保证服务质量了怎么办？
1.1 主从作用
- 实时灾备，用于故障切换
- 读写分离，提供查询服务
- 备份，避免影响业务（这里的备份不是指数据库的备份，而是服务器的备份，相当于一台备用服务器）
1.2 主从形式
- 一主一从
- 主主复制
- 一主多从---扩展系统读取的性能，因为读是在从库读取的
- 多主一从---5.7开始支持
- 联级复制
2. 主从复制原理
主从复制步骤：
- 主库将所有的写操作记录到binlog日志中并生成一个log dump线程，将binlog日志传给从库的I/O线程
- 从库生成两个线程，一个I/O线程，一个SQL线程
- I/O线程去请求主库的binlog，并将得到的binlog日志写到relay log（中继日志） 文件中
- SQL线程，会读取relay log文件中的日志，并解析成具体操作，来实现主从的操作一致，达到最终数据一致的目的
3. 主从复制配置
主从复制配置步骤：
1.确保从数据库与主数据库里的数据一样
2.在主数据库里创建一个同步账号授权给从数据库使用
3.配置主数据库（修改配置文件）
4.配置从数据库（修改配置文件）
需求：
搭建两台MySQL服务器，一台作为主服务器，一台作为从服务器，主服务器进行写操作，从服务器进行读操作
环境说明：
| 数据库角色 | IP | 应用与系统版本 | 有无数据 |
|---|---|---|---|
| 主数据库 | 192.168.153.152 | centos7/redhat7 mysql-5.7 |
无数据到有数据 |
| 从数据库 | 192.168.153.162 | centos7/redhat7 mysql-5.7 |
无数据 |
| 从数据库 | 192.168.153.164 | centos7/redhat7 mysql-5.7 |
无数据 |
3.1 mysql安装
[root@localhost ~]# groupadd -r -g 306 mysql
[root@localhost ~]# useradd -M -s /sbin/nologin -g 306 -u 306 mysql
[root@localhost ~]# tar xf mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz -C /usr/local/
[root@localhost ~]# cd /usr/local/
[root@localhost local]# ln -sv mysql-5.7.22-linux-glibc2.12-x86_64 mysql
"mysql" -> "mysql-5.7.22-linux-glibc2.12-x86_64"
[root@localhost local]# chown -R mysql.mysql /usr/local/mysql*
[root@localhost local]# ll /usr/local/mysql -d
lrwxrwxrwx. 1 mysql mysql 35 5月 15 23:26 /usr/local/mysql -> mysql-5.7.22-linux-glibc2.12-x86_64
[root@localhost local]# ls
bin games lib libexec mysql-5.7.22-linux-glibc2.12-x86_64 share
etc include lib64 mysql sbin src
[root@localhost local]# cd
[root@localhost ~]# echo 'export PATH=/usr/local/mysql/bin:$PATH' > /etc/profile.d/mysql.sh
[root@localhost ~]# . /etc/profile.d/mysql.sh
[root@localhost ~]# mkdir /opt/data
[root@localhost ~]# chown -R mysql.mysql /opt/data/
[root@localhost ~]# /usr/local/mysql/bin/mysqld --initialize --user=mysql --datadir=/opt/data/
2019-05-15T15:33:17.059360Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2019-05-15T15:33:17.309490Z 0 [Warning] InnoDB: New log files created, LSN=45790
2019-05-15T15:33:17.634883Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2019-05-15T15:33:17.910710Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: c33692ba-7726-11e9-8825-000c29c97322.
2019-05-15T15:33:17.911242Z 0 [Warning] Gtid table is not ready to be used. Table 'mysql.gtid_executed' cannot be opened.
2019-05-15T15:33:17.911859Z 1 [Note] A temporary password is generated for root@localhost: %l.lUhAhl4;n
[root@localhost ~]# echo '%l.lUhAhl4;n' > pass
[root@localhost ~]# cp -a /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
[root@localhost ~]# cp -a /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
[root@localhost ~]# sed -ri 's#^(basedir=).*#\1/usr/local/mysql#g' /etc/init.d/mysqld
[root@localhost ~]# sed -ri 's#^(datadir=).*#\1/opt/data#g' /etc/init.d/mysqld
[root@localhost ~]# /etc/init.d/mysqld start
Starting MySQL.Logging to '/opt/data/localhost.localdomain.err'.
SUCCESS!
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
3.2 mysql主从配置
3.2.1 确保从数据库与主数据库里的数据一样(两个里面都无数据)
3.2.2 在主数据库里创建一个同步账号授权给从数据库使用
mysql> set password=password('ly123');
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
mysql> create user 'repl'@'192.168.153.162' identified by 'repl123';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.153.162';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> quit
3.2.3 配置主数据库
[root@localhost ~]# vim /etc/my.cnf
//在[mysqld]这段的后面加上如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-bin=mysql-bin //启用binlog日志
server-id=1 //数据库服务器唯一标识符，主库的server-id值必须比从库的小
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启mysql服务
[root@localhost ~]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//查看主库的状态
[root@localhost ~]# mysql -uroot -ply123
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.22-log MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 154 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
3.2.4 配置从数据库
[root@localhost ~]# vim /etc/my.cnf
//添加如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
server-id=2 //设置从库的唯一标识符，从库的server-id值必须大于主库的该值
relay-log=mysql-relay-bin //启用中继日志relay-log
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启从库的mysql服务
[root@localhost ~]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//配置并启动主从复制
mysql> change master to master_host='192.168.153.152',master_user='repl',mastter_password='repl123',master_log_file='mysql-bin.000001',master_log_pos=154;;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
//查看从服务器状态
mysql> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.153.152
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000004
Slave_IO_Running: Yes //此处必须为Yes
Slave_SQL_Running: Yes //此处必须为Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 154
Relay_Log_Space: 527
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: 1
Master_UUID: eec564cd-7744-11e9-8dfe-000c29c97322
Master_Info_File: /opt/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave 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:
1 row in set (0.00 sec)
3.2.5 测试验证
在主服务器的liucongrong库的student表中插入数据
mysql> create database liucongrong;
Query OK, 1 row affected (0.00 sec)
mysql> use liucongrong;
Database changed
mysql> create table student(name varchar(100),age tinyint);
Query OK, 0 rows affected (0.02 sec)
mysql> insert student values ('tom',29),('jerry',20);
Query OK, 2 rows affected (0.04 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> select * from student;
+-------+------+
| name | age |
+-------+------+
| tom | 29 |
| jerry | 20 |
+-------+------+
2 rows in set (0.00 sec)
在从数据库中查看数据是否同步：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| liucongrong |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> select * from liucongrong.student;
+-------+------+
| name | age |
+-------+------+
| tom | 29 |
| jerry | 20 |
+-------+------+
2 rows in set (0.00 sec)
4.mysql主从配置
4.1确保从数据库与主数据库里的数据一样
为确保从数据库与主数据库里的数据一样，先全备主数据库并还原到从数据库中
//先查看主库有哪些库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| liucongrong |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
//再查看从库有哪些库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
//全备主库
//全备主库时需要另开一个终端，给数据库加上读锁，避免在备份期间有其他人在写入导致数据不一致
mysql> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.00 sec)
//此锁表的终端必须在备份完成以后才能退出
//备份主库并将备份文件传送到从库
[root@localhost ~]# mysqldump -uroot -ply123 --all-databases > /root/all.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# ls
all.sql
anaconda-ks.cfg
mysql-5.7.22-linux-glibc2.12-x86_64.tar.gz
pass
[root@localhost ~]# scp /root/all.sql root@192.168.153.164:/root/
The authenticity of host '192.168.153.164 (192.168.153.164)' can't be established.
ECDSA key fingerprint is SHA256:NoDuGXDlaqriTX1RFynwCDbRXu2QrfUpNwZyglaGUdI.
ECDSA key fingerprint is MD5:10:35:ff:d9:f7:cd:8a:0a:8d:63:72:11:29:28:d3:fa.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.153.164' (ECDSA) to the list of known hosts.
root@192.168.153.164's password:
Permission denied, please try again.
root@192.168.153.164's password:
a 100% 784KB 50.3MB/s 00:00
//解除主库的锁表状态，直接退出交互式界面即可
mysql> quit
Bye
//在从库上恢复主库的备份并查看从库有哪些库，确保与主库一致
[root@localhost ~]# mysql -uroot -ply123 < /root/all.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@localhost ~]# mysql -uroot -ply123
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.22 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> select * from liucongrong.student;
+-------+------+
| name | age |
+-------+------+
| tom | 29 |
| jerry | 20 |
+-------+------+
2 rows in set (0.00 sec)
4.1.2在主数据库里创建一个同步账号授权给从数据库使用
mysql> CREATE USER 'repl'@'192.168.153.164' IDENTIFIED BY 'repl123';
Query OK, 0 rows affected (0.01 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.153.164';
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
4.1.3配置主数据库
[root@localhost ~]# vim /etc/my.cnf
//在[mysqld]这段的后面加上如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-bin=mysql-bin //启用binlog日志
server-id=1 //数据库服务器唯一标识符，主库的server-id值必须比从库的小
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启mysql服务
[root@localhost ~]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//查看主库的状态
[root@localhost ~]# mysql -uroot -ply123
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.22-log MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 154 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
4.1.3 配置从数据库
[root@localhost ~]# vim /etc/my.cnf
//添加如下内容
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
server-id=4 //设置从库的唯一标识符，从库的server-id值必须小于主库的该值
relay-log=mysql-relay-bin //启用中继日志relay-log
symbolic-links=0
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
//重启从库的mysql服务
[root@localhost ~]# systemctl restart mysqld
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
LISTEN 0 80 :::3306 :::*
//配置并启动主从复制
mysql> CHANGE MASTER TO
-> MASTER_HOST='192.168.153.152',
-> MASTER_USER='repl',
-> MASTER_PASSWORD='repl123',
-> MASTER_LOG_FILE='mysql-bin.000004',
-> MASTER_LOG_POS=1443;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.153.152
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 1443
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000004
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 1443
Relay_Log_Space: 527
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: 1
Master_UUID: eec564cd-7744-11e9-8dfe-000c29c97322
Master_Info_File: /opt/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave 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:
1 row in set (0.00 sec)
4.1.4测试验证
在主库插入数据
mysql> insert student values ('zhangsan',20),('lisi',18);
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> select * from student;
+----------+------+
| name | age |
+----------+------+
| tom | 29 |
| jerry | 20 |
| zhangsan | 20 |
| lisi | 18 |
+----------+------+
4 rows in set (0.00 sec)
在从数据库中查看数据是否同步：
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
mysql> select * from liucongrong.student;
+----------+------+
| name | age |
+----------+------+
| tom | 29 |
| jerry | 20 |
| zhangsan | 20 |
| lisi | 18 |
+----------+------+
4 rows in set (0.00 sec)
