欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  数据库

在mysql 5.7 中如何开启半同步复制

程序员文章站 2022-03-22 20:02:15
...

1.安装相关的插件

show plugins;  查看模块
help --uninstall; 查看卸载模块
master:
mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';  --安装 semisync_master.so插件 
Query OK, 0 rows affected (0.03 sec)
slave:
root@localhost [zw3306]>install plugin rpl_semi_sync_slave soname 'semisync_slave.so'; --安装 semisync_slave.so插件
Query OK, 0 rows affected (0.00 sec)
root@localhost [zw3306]>install plugin rpl_semi_sync_master soname 'semisync_master.so';
Query OK, 0 rows affected (0.00 sec)

2.修改的参数:

set global rpl_semi_sync_master_enabled=1;
set global rpl_semi_sync_master_timeout=1000;
set global rpl_semi_sync_slave_enabled=1;

也可以直接写到配置文件 [mysqld]

master:
[mysqld]
rpl_semi_sync_master_enabled = 1 
rpl_semi_sync_master_timeout = 1000 # 1 second
slave:
[mysqld]
rpl_semi_sync_slave_enabled = 1

修改了参数需要重启:

查看修改的参数

master: 
mysql> show global variables like '%rpl_semi%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 1000       |
| 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 |
+-------------------------------------------+------------+
6 rows in set (0.00 sec)


slave:
root@localhost [(none)]>show global variables like '%rpl_semi%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 1000       |
| 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 |
| rpl_semi_sync_slave_enabled               | ON         |
| rpl_semi_sync_slave_trace_level           | 32         |
+-------------------------------------------+------------+
8 rows in set (0.00 sec)


如果:如果原来是已经建好的复制结构很简单:

stop slave io_thread;
start slave io_thread;


3.做同步

change master to master_host='192.168.26.233', master_port=3306, master_user='repl',master_password='repl', master_auto_position=1;
 
root@localhost [(none)]>start slave;
Query OK, 0 rows affected (0.01 sec)
root@localhost [(none)]>show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.26.233
                  Master_User: repl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000002
          Read_Master_Log_Pos: 194
               Relay_Log_File: relay-bin.000004
                Relay_Log_Pos: 407
        Relay_Master_Log_File: mysql-bin.000002
             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: 194
              Relay_Log_Space: 861
              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: 3306100
                  Master_UUID: 7e354a2c-6f5f-11e6-997d-005056a36f08
             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: 7e354a2c-6f5f-11e6-997d-005056a36f08:1-9
            Executed_Gtid_Set: 7e354a2c-6f5f-11e6-997d-005056a36f08:1-9,
ba0d5587-74d6-11e6-ab5c-005056a3f46e:1-2
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)
ERROR: 
No query specified

5.查看slave是否有数据

root@localhost [zw3306]>show tables;


+------------------+
| Tables_in_zw3306 |
+------------------+
| t1               |
+------------------+
1 row in set (0.00 sec)



root@localhost [zw3306]>select * from t1;
+------+
| id   |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
+------+
4 rows in set (0.00 sec)


6. 怎么确认是同步还是半同步?

show global variables like '%semi%';
show global status like '%semi%';
master:
root@localhost [zw3306]>show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 1     | 有多少个Semi-sync的备库
| Rpl_semi_sync_master_net_avg_wait_time     | 0     | 事务提交后,等待备库响应的平均时间
| Rpl_semi_sync_master_net_wait_time         | 0     | 等待网络响应的总次数
| Rpl_semi_sync_master_net_waits             | 7     | 总的网络等待时间
| Rpl_semi_sync_master_no_times              | 0     | 一共有几次从Semi-sync跌回普通状态
| Rpl_semi_sync_master_no_tx                 | 0     | 库未及时响应的事务数,如果这个值很大就有问题
| Rpl_semi_sync_master_status                | ON    | 主库上Semi-sync是否正常开启
| Rpl_semi_sync_master_timefunc_failures     | 0     | 时间函数未正常工作的次数
| Rpl_semi_sync_master_tx_avg_wait_time      | 410   | 开启Semi-sync,事务返回需要等待的平均时间
| Rpl_semi_sync_master_tx_wait_time          | 2876  | 事务等待备库响应的总时间
| Rpl_semi_sync_master_tx_waits              | 7     | 事务等待备库响应的总次数
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     | 改变当前等待最小二进制日志的次数
| Rpl_semi_sync_master_wait_sessions         | 0     | 当前有几个线程在等备库响应
| Rpl_semi_sync_master_yes_tx                | 7     | Semi-sync模式下,成功的事务数
+--------------------------------------------+-------+
15 rows in set (0.00 sec)


root@localhost [zw3306]>show global variables like '%semi%';
+-------------------------------------------+------------+
| Variable_name                             | Value      |
+-------------------------------------------+------------+
| rpl_semi_sync_master_enabled              | ON         |
| rpl_semi_sync_master_timeout              | 1000       |
| 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 |
| rpl_semi_sync_slave_enabled               | ON         |
| rpl_semi_sync_slave_trace_level           | 32         |
+-------------------------------------------+------------+
8 rows in set (0.00 sec)


Rpl_semi_sync_master_no_tx 如果这个值很大就有问题

也有其他的原因;

mysql> show global status like '%semi%';
+--------------------------------------------+-------+
| Variable_name                              | Value |
+--------------------------------------------+-------+
| Rpl_semi_sync_master_clients               | 1     |
| Rpl_semi_sync_master_net_avg_wait_time     | 0     |
| Rpl_semi_sync_master_net_wait_time         | 0     |
| Rpl_semi_sync_master_net_waits             | 17    |
| Rpl_semi_sync_master_no_times              | 1     |
| Rpl_semi_sync_master_no_tx                 | 10    | 不是用半同步复制的
| Rpl_semi_sync_master_status                | OFF   |
| Rpl_semi_sync_master_timefunc_failures     | 0     |
| Rpl_semi_sync_master_tx_avg_wait_time      | 410   |
| Rpl_semi_sync_master_tx_wait_time          | 2876  |
| Rpl_semi_sync_master_tx_waits              | 7     |
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     |
| Rpl_semi_sync_master_wait_sessions         | 0     |
| Rpl_semi_sync_master_yes_tx                | 7     |
+--------------------------------------------+-------+
14 rows in set (0.01 sec)


操作10个事物,可以发现都是  Rpl_semi_sync_master_no_tx 
master接收到N个slave的应答后,才commit事物,等待1s用户可以设置应道slave的数量。
rpl_semi_sync_master_wait_for_slave_count=1 默认是1 
set global rpl_semi_sync_master_wait_for_slave_count=2;

意思是多少个半同步的slave;

以上就是在mysql 5.7 中如何开启半同步复制 的详细内容,更多请关注其它相关文章!