原理:
传统的mysql复制就是主-从复制,它会有一个主,一个或多个从,在主节点提交与执行完事物之后,通过日志文件,将其(异步的)发送到从节点上, 以重新执行(在基于语句的复制中),或应用(在基于行的复制中),默认情况下所有的server成员都有一个完整的数据库副本
当从节点连上主节点后,会向主节点发送上次同步的位置,主节点将日志文件发给从节点
主从复制分两种,异步复制与半同步复制,mysql默认异步复制
mysql主从复制 (二进制方式)
mysql-community-client.x86_64 0:5.7.17-1.el6 mysql-community-common.x86_64 0:5.7.17-1.el6 mysql-community-libs.x86_64 0:5.7.17-1.el6
mysql-community-libs-compat.x86_64 0:5.7.17-1.el6 mysql-community-server.x86_64 0:5.7.17-1.el6 /etc/init.d/mysqld start
set global validate_password_policy=0;
set global validate_password_length=4; #可以更改数据库密码限制的等级mysql_secure_installation
ALTER USER root@localhost identified by 'redhat'; #进入数据库修改密码master
修改/etc/my.cnf
最后添加
server-id=1
log-bin=mysql-bin #开启二进制slave
server-id=2进入数据库
master
1：创建共享用户
mysql> grant replication slave on *.* to mysql@'172.25.12.2' identified by 'redhat';
Query OK, 0 rows affected, 1 warning (0.44 sec)
2：刷新
mysql> flush privileges;
Query OK, 0 rows affected (0.17 sec)
3：查看
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000001 | 599 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
4：创建 共享目录
mysql> create database westos;
Query OK, 1 row affected (0.13 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| westos |
+--------------------+
5 rows in set (0.00 sec)
#创建table；
mysql> use westos;
Database changed
mysql> create table usertb (
-> username varchar(20) not null,
-> password varchar(30) not null);
Query OK, 0 rows affected (1.41 sec)
mysql> desc usertb;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(20) | NO | | NULL | |
| password | varchar(30) | NO | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
#插入数据
mysql> insert into usertb values ('user1','123');
Query OK, 1 row affected (0.31 sec)slave
连接
mysql> change master to master_host='172.25.12.1',master_user='mysql',master_password='redhat',master_log_file='mysql-bin.000001',master_log_pos=599;
Query OK, 0 rows affected, 2 warnings (1.70 sec)
mysql> start slave;
Query OK, 0 rows affected (0.17 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 172.25.12.1
Master_User: mysql
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 599
Relay_Log_File: server2-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000001
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: 599
Relay_Log_Space: 529
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: db2b6e93-0498-11e8-9b4d-525400f2a3c0
Master_Info_File: /var/lib/mysql/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)
ERROR:
No query specified
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| westos |
+--------------------+
5 rows in set (0.00 sec)
mysql> use westos;
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_westos |
+------------------+
| usertb |
+------------------+
1 row in set (0.00 sec)
mysql> desc usertb;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| username | varchar(20) | NO | | NULL | |
| password | varchar(30) | NO | | NULL | |
+----------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> select * from usertb;
+----------+----------+
| username | password |
+----------+----------+
| user1 | 123 |
+----------+----------+
1 row in set (0.00 sec)半同步复制配置
mysql默认异步复制,在设置成半同步之后,如果节点出了问题(master收不到slave的ack返回值),一定的等待时间之后,系统就会自动切换回异步复制.
配置
主节点(master):
mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';
mysql> set global rpl_semi_sync_master_enabled=ON;
mysql> show global variables like '%semi%';
+-------------------------------------------+------------+
| Variable_name | Value |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled | ON |
| rpl_semi_sync_master_timeout | 10000 |
| rpl_semi_sync_master_trace_level | 32 |
| rpl_semi_sync_master_wait_for_slave_count | 1 |
| rpl_semi_sync_master_wait_no_slave | ON |
| rpl_semi_sync_master_wait_point | AFTER_SYNC |
+-------------------------------------------+------------+从节点配置
mysql> install plugin rpl_semi_sync_slave soname 'semisync_slave.so';
mysql> set global rpl_semi_sync_slave_enabled=ON;
mysql> stop slave io_thread;
mysql> start slave io_thread;
mysql> show global variables like '%semi%';
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled | ON |
| rpl_semi_sync_slave_trace_level | 32 |
+---------------------------------+-------+插入检测:
#往test库的test表里插入一条数据
mysql> insert into test.test value ('user3');
Query OK, 1 row affected (0.11 sec)
mysql> show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 1 | #半同步连接数
| Rpl_semi_sync_master_net_avg_wait_time | 0 |
| Rpl_semi_sync_master_net_wait_time | 0 |
| Rpl_semi_sync_master_net_waits | 1 |
| Rpl_semi_sync_master_no_times | 0 |
| Rpl_semi_sync_master_no_tx | 0 | #失败次数
| Rpl_semi_sync_master_status | ON | #连接状态
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 415 |
| Rpl_semi_sync_master_tx_wait_time | 415 |
| Rpl_semi_sync_master_tx_waits | 1 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 1 | #成功次数
+--------------------------------------------+-------+
将slave的半同步关掉,进行插入测试:
slave:
mysql> set global rpl_semi_sync_slave_enabled=OFF;
mysql> stop slave io_thread;
mysql> start slave io_thread;
mysql> show global variables like '%semi%';
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| rpl_semi_sync_slave_enabled | OFF |
| rpl_semi_sync_slave_trace_level | 32 |
+---------------------------------+-------+master:
mysql> insert into test.test value ('user4');
Query OK, 1 row affected (10.08 sec)
#本次插入花费了十秒,因为异步复制有十秒等待slave发送ack的时间.
mysql> show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients | 0 |
| Rpl_semi_sync_master_net_avg_wait_time | 0 |
| Rpl_semi_sync_master_net_wait_time | 0 |
| Rpl_semi_sync_master_net_waits | 2 |
| Rpl_semi_sync_master_no_times | 1 |
| Rpl_semi_sync_master_no_tx | 1 |
| Rpl_semi_sync_master_status | OFF |
| Rpl_semi_sync_master_timefunc_failures | 0 |
| Rpl_semi_sync_master_tx_avg_wait_time | 458 |
| Rpl_semi_sync_master_tx_wait_time | 917 |
| Rpl_semi_sync_master_tx_waits | 2 |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0 |
| Rpl_semi_sync_master_wait_sessions | 0 |
| Rpl_semi_sync_master_yes_tx | 2 |
+--------------------------------------------+-------+