mysql主从复制
MySQL主从复制
目录
1.传统主从复制的原理
- 主库(master)将写操作记录到binlog日志中并生成一个log dump线程，将binlog日志传给binlog日志传给从库(slave)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，来实现主从操作的一致，最终达成数据一致的目的
2.主从复制的配置
主从复制配置步骤：
- 确保从数据库与主数据库里的数据一样
- 在主数据库里创建一个同步账号授权给从数据库使用
- 配置主数据库（修改配置文件）
- 配置从数据库（修改配置文件)
环境准备
| 角色 | IP | 系统版本/mysql版本 |
|---|---|---|
| master | 192.168.169.139 | centos8/mysql-5.7 |
| slave | 192.168.169.140 | centos8/mysql-5.7 |
2.1 安装mysql
分别在主从两台服务器上安装mysql-5.7版本，过程请参考《mysql基础》与《mysql进阶》。
2.2 mysql主从配置
2.2.1 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
//关闭防火墙(两台都需要关闭)
systemctl stop firewalld
//先查看主库有哪些数据库
[root@master ~]# mysql -e 'show databases;'
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| zzd |
+--------------------+
//查看从库有哪些数据库
[root@slave ~]# mysql -e 'show databases;'
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
//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)
//备份主库并将备份文件传送到从库
[root@master ~]# mysqldump --all-databases > all-$(date +'%Y%m%d%H%M%S').sql
[root@master ~]# scp all-20220802003132.sql root@192.168.169.140:/root
The authenticity of host '192.168.169.140 (192.168.169.140)' can't be established.
ECDSA key fingerprint is SHA256:h0JBqfyD7nmBvCwBazGyK6b50D/gE11IG/dW6E3J1Ug.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.169.140' (ECDSA) to the list of known hosts.
root@192.168.169.140's password:
all-20220802003132.sql 100% 857KB 97.9MB/s 00:00
//解除数据库锁定状态
mysql> exit
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@slave ~]# ls
all-20220802003132.sql anaconda-ks.cfg pass
[root@slave ~]# mysql < all-20220802003132.sql
[root@slave ~]# mysql -e 'show databases;'
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| zzd |
+--------------------+
2.2.2 在主数据库里创建一个同步账号授权给从数据库使用
mysql> grant replication slave on *.* to repl@'192.168.169.140' identified by 'repl140!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
2.2.3 配置主数据库
[root@master ~]# vim /etc/my.cnf
//在[mysqld]这段的后面加上如下内容
log-bin = mysql_bin #开启binlog日志
server-id = 10 #数据库服务器唯一标识符，从库的server-id值必须比主库的大
symbolic-links = 0
//重启mysql服务
[root@master ~]# systemctl restart mysqld.service
//查看主库的状态
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql_bin.000021 | 154 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
2.2.4 配置从数据库
[root@slave ~]# vim /etc/my.cnf
//在[mysqld]这段的后面加上如下内容
server-id = 20 #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
//重启mysql服务
[root@slave ~]# systemctl restart mysqld.service
//配置并启动主从复制
mysql> change master to
-> master_host='192.168.169.139',
-> master_user='repl',
-> master_password='repl140!',
-> master_log_file='mysql_bin.000021',
-> 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;
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.169.139
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql_bin.000022
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-relay-bin.000003
Relay_Log_Pos: 367
Relay_Master_Log_File: mysql_bin.000022
Slave_IO_Running: Yes #必须为yes
Slave_SQL_Running: Yes #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: 740
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: 10
Master_UUID: c8900af2-0d8b-11ed-b3bc-000c29f177ce
Master_Info_File: /opt/mysql/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)
2.2.5 进行测试
在主数据库上进行创建数据库操作
//创建数据库
mysql> create database zic;
Query OK, 1 row affected (0.00 sec)
mysql> use zic
Database changed
//创建表
mysql> create table test1(id int not null,name varchar(50));
Query OK, 0 rows affected (0.00 sec)
在从数据库上面进行验证
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| zic |
| zzd |
+--------------------+
6 rows in set (0.00 sec)
mysql> use zic;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> show tables;
+---------------+
| Tables_in_zic |
+---------------+
| test1 |
+---------------+
1 row in set (0.00 sec)
mysql> desc test1;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(11) | NO | | NULL | |
| name | varchar(50) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
3.GTID主从
3.1 GTID工作原理
- master更新数据时，会在事务前产生GTID，一同记录到binlog日志中。
- slave端的i/o 线程将变更的binlog，写入到本地的relay log中。
- sql线程从relay log中获取GTID，然后对比slave端的binlog是否有记录。
- 如果有记录，说明该GTID的事务已经执行，slave会忽略。
- 如果没有记录，slave就会从relay log中执行该GTID的事务，并记录到binlog。
- 在解析过程中会判断是否有主键，如果没有就用二级索引，如果没有就用全部扫描。
3.2 GTID主从配置
环境准备
| 角色 | IP | 系统版本/mysql版本 |
|---|---|---|
| master | 192.168.169.139 | centos8/mysql-5.7 |
| slave | 192.168.169.140 | centos8/mysql-5.7 |
主库配置
//编辑my.cnf文件
[root@master ~]# vim /etc/my.cnf
//添加以下内容
server-id = 10
log-bin = mysql_bin
gtid_mode = on
enforce-gtid-consistency = true
log-slave-updates = on
//重启mysql服务
[root@master ~]# systemctl restart mysqld.service
从库配置
//编辑my.cnf文件
[root@slave ~]# vim /etc/my.cnf
//添加以下内容
server-id = 20
relay-log = myrelay
gtid_mode = on
enforce-gtid-consistency = true
log-slave-updates = on
read_only = on
master-info-repository = TABLE
relay-log-info-repository = TABLE
//重启mysql服务
[root@slave ~]# systemctl restart mysqld.service
主库授权复制用户
mysql> grant replication slave on *.* to repl@'%' identified by 'repl123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
从库设置要同步的主库信息，并开启同步。
mysql> change master to
-> master_host='192.168.169.139',
-> master_port=3306,
-> master_user='repl',
-> master_password='repl123!',
-> master_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
//查看从库状态
mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.169.139
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql_bin.000011
Read_Master_Log_Pos: 437
Relay_Log_File: myrelay.000002
Relay_Log_Pos: 650
Relay_Master_Log_File: mysql_bin.000011
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: 437
Relay_Log_Space: 849
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: 10
Master_UUID: c8900af2-0d8b-11ed-b3bc-000c29f177ce
Master_Info_File: mysql.slave_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: c8900af2-0d8b-11ed-b3bc-000c29f177ce:1
Executed_Gtid_Set: c8900af2-0d8b-11ed-b3bc-000c29f177ce:1
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
