mysql 5.7 開啓半同步複製

https://blog.csdn.net/isoleo/article/details/77892950

1.安裝相關的插件

show plugins;  查看模塊
help --uninstall; 查看卸載模塊

master:

mysql> install plugin rpl_semi_sync_master soname 'semisync_master.so';  --安裝 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'; --安裝 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.修改的參數：

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

也能夠直接寫到配置文件 [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

修改了參數須要重啓：

查看修改的參數

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)

若是：若是原來是已經建好的複製結構很簡單：

stop slave io_thread;
start slave io_thread;

3.作同步

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是否有數據

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. 怎麼確認是同步仍是半同步？

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     | 有多少個Semi-sync的備庫
| Rpl_semi_sync_master_net_avg_wait_time     | 0     | 事務提交後，等待備庫響應的平均時間
| Rpl_semi_sync_master_net_wait_time         | 0     | 等待網絡響應的總次數
| Rpl_semi_sync_master_net_waits             | 7     | 總的網絡等待時間
| Rpl_semi_sync_master_no_times              | 0     | 一共有幾回從Semi-sync跌回普通狀態
| Rpl_semi_sync_master_no_tx                 | 0     | 庫未及時響應的事務數,若是這個值很大就有問題
| Rpl_semi_sync_master_status                | ON    | 主庫上Semi-sync是否正常開啓
| Rpl_semi_sync_master_timefunc_failures     | 0     | 時間函數未正常工做的次數
| Rpl_semi_sync_master_tx_avg_wait_time      | 410   | 開啓Semi-sync，事務返回須要等待的平均時間
| Rpl_semi_sync_master_tx_wait_time          | 2876  | 事務等待備庫響應的總時間
| Rpl_semi_sync_master_tx_waits              | 7     | 事務等待備庫響應的總次數
| Rpl_semi_sync_master_wait_pos_backtraverse | 0     | 改變當前等待最小二進制日誌的次數
| Rpl_semi_sync_master_wait_sessions         | 0     | 當前有幾個線程在等備庫響應
| Rpl_semi_sync_master_yes_tx                | 7     | Semi-sync模式下，成功的事務數
+--------------------------------------------+-------+
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  若是這個值很大就有問題
也有其餘的緣由；

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    | 不是用半同步複製的
| 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)

操做10個事物，能夠發現都是  Rpl_semi_sync_master_no_tx 

master接收到N個slave的應答後，才commit事物，等待1s用戶能夠設置應道slave的數量。

rpl_semi_sync_master_wait_for_slave_count=1 默認是1 
set global rpl_semi_sync_master_wait_for_slave_count=2;

意思是多少個半同步的slave;