MySQL中基于GTID半同步如何搭建主从

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1. 背景

   * GTID: 全局事物ID(Global Transaction ID)，在整个事务架构中每一个事务ID号是全局唯一的，不止是在一个节点上而是整个主从复制架构中每任何两个事务的ID号都不会相同。

   * GTID就是由当前节点的UUID（一个128位的随机数）和为当前节点生成的自增数（TID）组成的。

   * GTID在分布式架构中可以保证数据的一致性。从而也实现了mysql的高可用性。

   * MySQL 5.6开始支持。 GTID在复制中代替原有的binlog file和file posIstion复制定位。

2. 环境

   * Master云服务器环境

mysql> system cat /etc/redhat-release
Centos release 6.8 (Final)

mysql> system ifconfig eth0  | sed -rn '2s#^.*addr:(.*)  Bca.*$#\1#gp'
172.18.0.1

mysql> show variables like 'version';
+---------------+------------+
| Variable_name | Value      |
+---------------+------------+
| version       | 5.7.18-log |
+---------------+------------+
1 row in set (0.00 sec)

   * Slave云服务器环境

mysql> system cat /etc/redhat-release
CentOS release 6.8 (Final)

mysql> system ifconfig eth0  | sed -rn '2s#^.*addr:(.*)  Bca.*$#\1#gp'
172.18.4.1

mysql> show variables like 'version';
+---------------+------------+
| Variable_name | Value      |
+---------------+------------+
| version       | 5.7.18-log |
+---------------+------------+
1 row in set (0.00 sec)

   * Master my.cnf配置文件

[mysqld]
########basic settings########
# 主从server-id一定要设置不同
server-id = 110
port = 3306
user = mysql
bind_address = 0.0.0.0    
character_set_server=utf8mb4
skip_name_resolve = 1
datadir = /data/mysql_data
log_error = error.log
#######replication settings########
# 开启 gtid
gtid_mode = on
# 强制gtid的一致性
enforce-gtid-consistency = true
master_info_repository = TABLE
relay_log_info_repository = TABLE
# MySQL复制是基于binlog日志的
log_bin = bin.log
sync_binlog = 1
log_slave_updates
# MySQL binlog格式搭建主从时必须设置为row
binlog_fORMat = row
relay_log = relay.log
relay_log_recovery = 1
slave_skip_errors = ddl_exist_errors
######semi sync replication settings########
# 设置插件目录路径
plugin_dir=/usr/local/mysql/lib/plugin
# 加载插件
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
# 开启master semi sync replication
loose_rpl_semi_sync_master_enabled = 1
# 开启slave semi sync replication
loose_rpl_semi_sync_slave_enabled = 1
# 等待5秒无ack应答自动切换为异步模式
loose_rpl_semi_sync_master_timeout = 5000

   * Slave my.cnf配置文件

[mysqld]
########basic settings########
gtid_mode = on
enforce-gtid-consistency = true
server-id = 210
port = 3306
user = mysql
bind_address = 0.0.0.0
character_set_server=utf8mb4
skip_name_resolve = 1
datadir = /data/mysql_data
log_error = error.log
#######replication settings########
master_info_repository = TABLE
relay_log_info_repository = TABLE
log_bin = bin.log
sync_binlog = 1
log_slave_updates
binlog_format = row
# slave上开启只读，避免应用误写导致主从数据不一致
read_only = on
relay_log = relay.log
relay_log_recovery = 1
binlog_gtid_simple_recovery = 1
slave_skip_errors = ddl_exist_errors
######semi sync replication settings########
plugin_dir=/usr/local/mysql/lib/plugin
plugin_load = "rpl_semi_sync_master=semisync_master.so;rpl_semi_sync_slave=semisync_slave.so"
loose_rpl_semi_sync_master_enabled = 1
loose_rpl_semi_sync_slave_enabled = 1
loose_rpl_semi_sync_master_timeout = 5000
rpl_semi_sync_master_wait_point = AFTER_SYNC
rpl_semi_sync_master_wait_for_slave_count = 1

3. 搭建基于GTID半同步复制主从

   * master 创建复制所使用的用户 [ 此处ip设置为slave服务IP或者% ]

mysql> grant replication slave on *.* to 'rpl'@'172.18.4.1' identified by '123';
Query OK, 0 rows affected, 1 warning (0.00 sec)

   * slave云服务器上配置连接master信息

     未开启slave服务时，Slave_IO_Running与Slave_SQL_Running状态成No

mysql> show slave status;        # 未开启复制功能时，slave状态是空的
Empty set (0.00 sec) 

mysql>  change master to master_host='172.18.0.1',master_user='rpl',master_passWord='123',master_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.02 sec)

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: 
                  Master_Host: 172.18.0.1
                  Master_User: rpl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: 
          Read_Master_Log_Pos: 4
               Relay_Log_File: relay.000001
                Relay_Log_Pos: 4
        Relay_Master_Log_File: 
             Slave_IO_Running: No
            Slave_SQL_Running: No
              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: 0
              Relay_Log_Space: 154
              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: NULL
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: 0
                  Master_UUID: 
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
           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: e5b2d96a-7047-11e7-b39c-00163e028c02:1
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

   * 开启slave服务，并查看状态

     正常开启slave服务后，Slave_IO_Running与Slave_SQL_Running状态成Yes

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.18.0.1
                  Master_User: rpl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: bin.000002
          Read_Master_Log_Pos: 689
               Relay_Log_File: relay.000002
                Relay_Log_Pos: 890
        Relay_Master_Log_File: 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: 689
              Relay_Log_Space: 1087
              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: 110
                  Master_UUID: aaa45482-7047-11e7-a7b3-00163e0432c5
             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: aaa45482-7047-11e7-a7b3-00163e0432c5:1-2
            Executed_Gtid_Set: aaa45482-7047-11e7-a7b3-00163e0432c5:1-2,
e5b2d96a-7047-11e7-b39c-00163e028c02:1
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

   * master 查看slave连接信息

mysql> show slave hosts;
+-----------+------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID                           |
+-----------+------+------+-----------+--------------------------------------+
|       210 |      | 3306 |       110 | e5b2d96a-7047-11e7-b39c-00163e028c02 |
+-----------+------+------+-----------+--------------------------------------+
1 row in set (0.00 sec)

   * Master上操作创建数据库与表，并插入数据

mysql> create database mytest character set utf8mb4;
Query OK, 1 row affected (0.02 sec)

mysql> use mytest;
Database changed
mysql> create table a(data INT PRIMARY KEY NOT NULL AUTO_INCREMENT)ENGINE=INNODB DEFAULT CHARSET=utf8mb4;
Query OK, 0 rows affected (0.02 sec)

mysql> insert into a select null;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> insert into a select null;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> insert into a select null;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
+------+
3 rows in set (0.00 sec)

   * slave上查看

mysql> select * from mytest.a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
+------+
3 rows in set (0.00 sec)

4. slave误写，gtid错误解决

   * master数据查看

mysql> select * from mytest.a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
+------+
3 rows in set (0.00 sec)

   * slave数据查看

mysql> select * from mytest.a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
+------+
3 rows in set (0.00 sec)

   * slave数据误写

mysql> insert into mytest.a select null;
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from mytest.a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
+------+
4 rows in set (0.00 sec)

   * master相同数据插入

mysql> insert into a select null;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select * from a;
+------+
| data |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
+------+
4 rows in set (0.00 sec)

   * slave云服务器状态查看  报1062错误，SQL线程停止工作，由于开启gtid不能设置跳过错误

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.18.0.1
                  Master_User: rpl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: bin.000002
          Read_Master_Log_Pos: 5768
               Relay_Log_File: relay.000005
                Relay_Log_Pos: 1354
        Relay_Master_Log_File: bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: No
              Replicate_Do_DB: 
          Replicate_Ignore_DB: 
           Replicate_Do_Table: 
       Replicate_Ignore_Table: 
      Replicate_Wild_Do_Table: 
  Replicate_Wild_Ignore_Table: 
                   Last_Errno: 1062
                   Last_Error: Could not execute Write_rows event on table mytest.a; Duplicate entry '4' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log bin.000002, end_log_pos 5737
                 Skip_Counter: 0
          Exec_Master_Log_Pos: 5512
              Relay_Log_Space: 2601
              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: NULL
Master_SSL_Verify_Server_Cert: No
                Last_IO_Errno: 0
                Last_IO_Error: 
               Last_SQL_Errno: 1062
               Last_SQL_Error: Could not execute Write_rows event on table mytest.a; Duplicate entry '4' for key 'PRIMARY', Error_code: 1062; handler error HA_ERR_FOUND_DUPP_KEY; the event's master log bin.000002, end_log_pos 5737
  Replicate_Ignore_Server_Ids: 
             Master_Server_Id: 110
                  Master_UUID: aaa45482-7047-11e7-a7b3-00163e0432c5
             Master_Info_File: mysql.slave_master_info
                    SQL_Delay: 0
          SQL_Remaining_Delay: NULL
      Slave_SQL_Running_State: 
           Master_Retry_Count: 86400
                  Master_Bind: 
      Last_IO_Error_Timestamp: 
     Last_SQL_Error_Timestamp: 170724 17:15:51
               Master_SSL_Crl: 
           Master_SSL_Crlpath: 
           Retrieved_Gtid_Set: aaa45482-7047-11e7-a7b3-00163e0432c5:10-23
            Executed_Gtid_Set: aaa45482-7047-11e7-a7b3-00163e0432c5:1-22,
e5b2d96a-7047-11e7-b39c-00163e028c02:1-5
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

   * slave云服务器停止复制

mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)

   * 设置gtid下一次执行 通过Retrieved_Gtid_Set和Executed_Gtid_Set得到未执行的gtid

mysql> set gtid_next = 'aaa45482-7047-11e7-a7b3-00163e0432c5:23';
Query OK, 0 rows affected (0.00 sec)

   * 执行空事物

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

   * 设置gtid下一次自动寻找gtid事物

mysql> set gtid_next = 'automatic';
Query OK, 0 rows affected (0.00 sec)

   * slave云服务器开启复制

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

   * slave云服务器查看状态 SQL线程正常开启工作

mysql> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 172.18.0.1
                  Master_User: rpl
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: bin.000002
          Read_Master_Log_Pos: 5768
               Relay_Log_File: relay.000006
                Relay_Log_Pos: 436
        Relay_Master_Log_File: 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: 5768
              Relay_Log_Space: 2089
              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: 110
                  Master_UUID: aaa45482-7047-11e7-a7b3-00163e0432c5
             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: aaa45482-7047-11e7-a7b3-00163e0432c5:10-23
            Executed_Gtid_Set: aaa45482-7047-11e7-a7b3-00163e0432c5:1-23,
e5b2d96a-7047-11e7-b39c-00163e028c02:1-5
                Auto_Position: 1
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)

5. 总结

以需求驱动技术，技术本身没有优略之分，只有业务之分。

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