专职DBA-MySQL主从延迟复制

专职DBA-MySQL主从延迟复制


本次实验环境延用MySQL主从异步复制的搭建环境

mysql集群企业级架构方案
1.根据对数据库的访问请求实现读写分离（读从写主）
2.根据不同的业务拆分多个从库以提供访问
    一主五从
    3从提供外部用户读请求访问（读写分离、LVS负载均衡）
    1从用于内部用户读访问（业务后台、数据分析、搜索业务、财务统计、定时任务、开发查询等）
    1从用于数据库定时全备份，以及增量备份（开启binlog）
3.实现对主库的高可用
    (1).heartbeat+dbrd+mysql方案
            通过dbrd工具对主数据库服务器实现基于block的异机物理复制，类似于网络RAID1.
            优点：速度很快。
            缺点：不能被访问，除非主节点宕机，备节点才可以提供访问。
    (2).mysql-MMM（Master-Master replication Manager）方案
            通过mysql的replication实现主主之间的数据同步。
            优点：可以实现slaves负载均衡。
            缺点：MMM无法完全保持数据的一致性。
    (3).mysql-MHA（Master High Availability）+keepalived方案
            通过mysql的replication实现数据库服务器之间的数据同步。
            优点：同时可以实现从库负载均衡，主库宕机后自动选择最优的从库，将其切换为主库。
                  并尽最大的努力对有所有的库做数据补全操作，一直到最新。
                  并对其他从库和新主库实现复制，再加上keepalived是为了实现vip漂移。
    (4).PXC
    (5).共享存储方案
    (6).数据库分布式部署方案
    (7).MGR


mysql企业级备份策略方案
1.利用mysql主从复制的从库进行数据备份策略
(1).选择一个不对外提供服务的从库，专门做数据备份用。
(2).开启从库的binlog功能。
(3).数据量小于30GB用mysqldump逻辑备份；
     数据库大于30GB用Xtrabackup物理热备工具。


mysql主从复制生产环境的常见延迟原因
易导致复制延迟的原因：
    1.一个主库的从库太多
    2.从库硬件比主库查
    3.慢sql语句过多
    4.主从复制的设计问题
    5.主从复制之间的网络延迟
    6.主库读写压力太大


mysql主从复制数据一致性企业级方案
1.采用半同步复制方案
2.当复制发生延迟时让程序改读主库


mysql多线程复制解决复制延迟实践
[root@db01 ~]# mysqld --defaults-file=/data/mysql/3306/my.cnf &
[root@db02 ~]# mysqld --defaults-file=/data/mysql/3306/my.cnf &


(1).查看当前slave服务器的SQL线程状态
[root@db02 ~]# mysql -S /data/mysql/3306/mysql.sock -p
Enter password:

Slave [(none)]> show processlist;
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                  | Info             |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
|  1 | system user |           | NULL | Connect |   49 | Waiting for master to send event                       | NULL             |
|  2 | system user |           | NULL | Connect |   48 | Slave has read all relay log; waiting for more updates | NULL             |
|  4 | root        | localhost | NULL | Query   |    0 | starting                                               | show processlist |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
3 rows in set (0.00 sec)


(2).检查多线程的参数配置
默认为0表示单线程复制
Slave [(none)]> show variables like "%parallel%";
+------------------------+----------+
| Variable_name          | Value    |
+------------------------+----------+
| slave_parallel_type    | DATABASE |
| slave_parallel_workers | 0        |
+------------------------+----------+
2 rows in set (0.01 sec)


(3).停止主从复制，在线修改线程数
Slave [(none)]> stop slave;
Query OK, 0 rows affected (0.00 sec)

Slave [(none)]> set global slave_parallel_workers = 4;
Query OK, 0 rows affected (0.00 sec)

Slave [(none)]> show variables like "%parallel%";
+------------------------+----------+
| Variable_name          | Value    |
+------------------------+----------+
| slave_parallel_type    | DATABASE |
| slave_parallel_workers | 4        |
+------------------------+----------+
2 rows in set (0.00 sec)


(4).启动主从复制，查看SQL线程数
Slave [(none)]> start slave;
Query OK, 0 rows affected (0.04 sec)

Slave [(none)]> show processlist;
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                  | Info             |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
|  4 | root        | localhost | NULL | Query   |    0 | starting                                               | show processlist |
|  5 | system user |           | NULL | Connect |   28 | Waiting for master to send event                       | NULL             |
|  6 | system user |           | NULL | Connect |   28 | Slave has read all relay log; waiting for more updates | NULL             |
|  7 | system user |           | NULL | Connect |   28 | Waiting for an event from Coordinator                  | NULL             |
|  8 | system user |           | NULL | Connect |   28 | Waiting for an event from Coordinator                  | NULL             |
|  9 | system user |           | NULL | Connect |   28 | Waiting for an event from Coordinator                  | NULL             |
| 10 | system user |           | NULL | Connect |   28 | Waiting for an event from Coordinator                  | NULL             |
+----+-------------+-----------+------+---------+------+--------------------------------------------------------+------------------+
7 rows in set (0.00 sec)


(5).想永久生效就写入my.cnf
[root@db02 ~]# vim /data/mysql/3306/my.cnf
[mysqld]
slave_parallel_workers = 4


让mysql主从复制的从库只读访问
1.read-only参数允许数据库更新的条件
(1).具有super权限的用户可以更新，不受read-only参数影响。例如：root
(2).来自从服务器具备主从复制权限的线程可以更新，不受read-only参数的影响。例如：rep
2.如何配置read-only参数
(1).启动数据库时直接带--read-only参数启动。
mysqld_safe --read-only --user=mysql &
(2).在my.cnf文件中配置
[root@db02 ~]# vim /data/mysql/3306/my.cnf
[mysqld]
read-only

然后重启数据库
mysqladmin -S /data/mysql/3306/mysql.sock -p shutdown
mysqld --defaults-file=/data/mysql/3306/my.cnf &


mysql主从复制读写分离Web用户生产设置方案
在配置好mysql主从复制，并实现了读写分离以后，数据库授权程序访问的用户设置方法：
1.主库和从库使用不同的用户，授予不同的权限。
    主库上对web_w用户的授权
    grant select,insert,update,delete on `web`.* to ‘web_w‘@‘192.168.10.%‘ identified by ‘123‘;

    从库上对web_r用户的授权
    grant select on `web`.* to ‘web_r‘@‘192.168.10.%‘ identified by ‘123‘;


2.网站程序访问主库和从库时使用一套用户密码。
(1).主库和从库使用相同的用户，但授予不同的权限。
忽略主库的mysql授权库同步
[root@db01 ~]# vim /data/mysql/3306/my.cnf
binlog-ignore-db = mysql     #mysql库不记录binlog日志
replicate-ignore-db = mysql  #忽略复制mysql库

在主库上创建完web用户和权限之后，在从库上revoke回收对应的更新权限
主库：grant select,insert,update,delete on `web`.* to ‘web‘@‘192.168.10.%‘ identified by ‘123‘;
从库：grant select on `web`.* to ‘web‘@‘192.168.10.%‘ identified by ‘123‘;

在从库上设置read-only参数，让从库只读
[root@db02 ~]# vim /data/mysql/3306/my.cnf
[mysqld]
read-only
然后重启数据库
mysqladmin -S /data/mysql/3306/mysql.sock -p shutdown
mysqld --defaults-file=/data/mysql/3306/my.cnf &




mysql主从延迟复制方案及恢复实践
[root@db02 ~]# mysql -S /data/mysql/3306/mysql.sock -p
Enter password:

Slave [(none)]> stop slave;
Query OK, 0 rows affected (0.01 sec)

Slave [(none)]> change master to master_delay = 60;
Query OK, 0 rows affected (0.01 sec)

Slave [(none)]> start slave;
Query OK, 0 rows affected (0.02 sec)

Slave [(none)]> show slave status\G
*************************** 1. row ***************************
                    SQL_Delay: 60 #延迟60秒进行复制
          SQL_Remaining_Delay: NULL #还剩多少秒执行复制
      Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates #sql线程状态


[root@db01 ~]# mysql -S /data/mysql/3306/mysql.sock -p
Enter password:

Master [(none)]> create database app;
Query OK, 1 row affected (0.00 sec)

Master [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
6 rows in set (0.00 sec)


Slave [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
5 rows in set (0.01 sec)


但是中继日志里面已经有创建的语句了，说明IO线程还是实时在工作的。
[root@db02 ~]# cd /data/mysql/3306/data/
[root@db02 /data/mysql/3306/data]# ls -l
total 122952
-rw-r----- 1 mysql mysql       56 Jul 15 05:52 auto.cnf
-rw-r----- 1 mysql mysql      206 Jul 16 01:43 db02-relay-bin.000001
-rw-r----- 1 mysql mysql      476 Jul 16 01:47 db02-relay-bin.000002
-rw-r----- 1 mysql mysql       48 Jul 16 01:43 db02-relay-bin.index
-rw-r----- 1 mysql mysql      599 Jul 15 06:54 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 16 01:23 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 16 01:23 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 15 05:52 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 16 01:23 ibtmp1
-rw-r----- 1 mysql mysql      122 Jul 16 01:48 master.info
drwxr-x--- 2 mysql mysql     4096 Jul 15 06:35 mysql
drwxr-x--- 2 mysql mysql     8192 Jul 15 05:52 performance_schema
-rw-r----- 1 mysql mysql       59 Jul 16 01:43 relay-log.info
drwxr-x--- 2 mysql mysql       48 Jul 15 06:50 shenzhen
drwxr-x--- 2 mysql mysql     8192 Jul 15 05:52 sys
-rw-r----- 1 mysql mysql       84 Jul 16 01:43 worker-relay-log.info.1
-rw-r----- 1 mysql mysql       84 Jul 16 01:43 worker-relay-log.info.2
-rw-r----- 1 mysql mysql       84 Jul 16 01:43 worker-relay-log.info.3
-rw-r----- 1 mysql mysql       84 Jul 16 01:43 worker-relay-log.info.4

[root@db02 /data/mysql/3306/data]# mysqlbinlog db02-relay-bin.000002
SET @@session.lc_time_names=0/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
create database app
/*!*/;


过了1分钟后
Slave [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
6 rows in set (0.00 sec)


mysql的延迟复制实际上影响的只是SQL线程将数据应用到从库。
而IO线程早已把主库更新的数据写到了从库的中继日志里面。
因此，在延迟复制期间，即使主库宕机了，从库到了延迟复制的时间，也依然会把数据更新到与主库宕机时一致。



使用mysql主从延迟复制进行数据恢复实践
1.模拟环境，将从库延迟调整为3600秒
[root@db02 ~]# mysql -S /data/mysql/3306/mysql.sock -p
Enter password:

Slave [(none)]> stop slave;
Query OK, 0 rows affected (0.01 sec)


[root@db02 ~]# mysql -u root -p -S /application/mysql/tmp/mysql.sock
Enter password:

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

Slave [(none)]> change master to master_delay = 3600;
Query OK, 0 rows affected (0.02 sec)

Slave [(none)]> start slave;
Query OK, 0 rows affected (0.03 sec)

Slave [(none)]> show slave status\G
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.10.11
                  Master_User: rep
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql-bin.000005
          Read_Master_Log_Pos: 350
               Relay_Log_File: db02-relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql-bin.000005
             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: 350
              Relay_Log_Space: 526
              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: 113306
                  Master_UUID: 7c145945-a680-11e9-baea-000c29a14cf7
             Master_Info_File: /data/mysql/3306/data/master.info
                    SQL_Delay: 3600
          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: 7c145945-a680-11e9-baea-000c29a14cf7:1-4
                Auto_Position: 0
         Replicate_Rewrite_DB: 
                 Channel_Name: 
           Master_TLS_Version: 
1 row in set (0.00 sec)


2.模拟在主库写入数据，每隔5秒写入一个库，就当是模拟用户写入数据了
for n in {01..05}
do
    mysql -S /data/mysql/3306/mysql.sock -p123 -e "create database app$n;"
    sleep 5
done

[root@db01 ~]# for n in {01..05}
> do
>     mysql -S /data/mysql/3306/mysql.sock -p123 -e "create database app$n;"
>     sleep 5
> done
mysql: [Warning] Using a password on the command line interface can be insecure.
mysql: [Warning] Using a password on the command line interface can be insecure.
mysql: [Warning] Using a password on the command line interface can be insecure.
mysql: [Warning] Using a password on the command line interface can be insecure.
mysql: [Warning] Using a password on the command line interface can be insecure.
[root@db01 ~]#


3.模拟人为破坏数据，也可以是不带where的update语句。
Master [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| app01              |
| app02              |
| app03              |
| app04              |
| app05              |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
11 rows in set (0.00 sec)


删除oldboy5数据库，后面要做的就是把这个数据库恢复回来，别的数据还得保留。
Master [(none)]> drop database app05;
Query OK, 0 rows affected (0.01 sec)

Master [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| app01              |
| app02              |
| app03              |
| app04              |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
10 rows in set (0.00 sec)

Master [(none)]> drop database app05;
Query OK, 0 rows affected (0.01 sec)

Master [(none)]> show databases like "%app%";
+------------------+
| Database (%app%) |
+------------------+
| app              |
| app01            |
| app02            |
| app03            |
| app04            |
+------------------+
5 rows in set (0.00 sec)

现在，所有的从库都已经是坏数据了，只有延迟从库是好的，但是是一个小时之前的数据。

4.当数据库出现误删数据的情况时，特别是update不加条件破坏数据，要想完整恢复数据，最好选择对外停止访问措施，此时需要牺牲用户体验了。
[root@db01 ~]# iptables -I INPUT -p tcp --dport 3306 ! -s 192.168.10.13 -j DROP
非192.168.10.13禁止访问数据库3306端口，11是主库IP，192.168.10.13为远程连接ssh客户端的IP。

5.登录主库从库查看binlog发送接收进行确认。
Master [(none)]> show processlist;
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
| Id | User | Host                | db   | Command     | Time | State                                                         | Info             |
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
|  5 | root | localhost           | NULL | Query       |    0 | starting                                                      | show processlist |
|  6 | rep  | 192.168.10.12:39828 | NULL | Binlog Dump |  754 | Master has sent all binlog to slave; waiting for more updates | NULL             |
+----+------+---------------------+------+-------------+------+---------------------------------------------------------------+------------------+
2 rows in set (0.00 sec)


从库
Slave [(none)]> show processlist;
+----+-------------+-----------+------+---------+------+----------------------------------------------------------------+------------------+
| Id | User        | Host      | db   | Command | Time | State                                                          | Info             |
+----+-------------+-----------+------+---------+------+----------------------------------------------------------------+------------------+
| 20 | root        | localhost | NULL | Query   |    0 | starting                                                       | show processlist |
| 21 | system user |           | NULL | Connect |  789 | Waiting for master to send event                               | NULL             |
| 22 | system user |           | NULL | Connect |  228 | Waiting until MASTER_DELAY seconds after master executed event | NULL             |
| 23 | system user |           | NULL | Connect |  789 | Waiting for an event from Coordinator                          | NULL             |
| 24 | system user |           | NULL | Connect |  789 | Waiting for an event from Coordinator                          | NULL             |
| 25 | system user |           | NULL | Connect |  789 | Waiting for an event from Coordinator                          | NULL             |
| 26 | system user |           | NULL | Connect |  789 | Waiting for an event from Coordinator                          | NULL             |
+----+-------------+-----------+------+---------+------+----------------------------------------------------------------+------------------+
7 rows in set (0.00 sec)

Slave [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
6 rows in set (0.00 sec)


6.在从库上停止主从复制，并查看数据库是否已同步过来。
Slave [(none)]> stop slave;
Query OK, 0 rows affected (0.01 sec)

Slave [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
6 rows in set (0.00 sec)
因为还未到延迟时间，所以数据不会同步到该延迟从库。


7.根据relay-log.info记录的sql线程读取relay-log的位置，解析未应用到从库的relay-bin日志。
进入中继日志所在的目录
[root@db02 ~]# cd /data/mysql/3306/data/
[root@db02 /data/mysql/3306/data]# ls -l
total 122952
drwxr-x--- 2 mysql mysql       20 Jul 16 01:48 app
-rw-r----- 1 mysql mysql       56 Jul 15 05:52 auto.cnf
-rw-r----- 1 mysql mysql      206 Jul 16 01:55 db02-relay-bin.000001
-rw-r----- 1 mysql mysql     1282 Jul 16 02:05 db02-relay-bin.000002
-rw-r----- 1 mysql mysql       48 Jul 16 01:55 db02-relay-bin.index
-rw-r----- 1 mysql mysql      599 Jul 15 06:54 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Jul 16 01:49 ibdata1
-rw-r----- 1 mysql mysql 50331648 Jul 16 01:49 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Jul 15 05:52 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Jul 16 01:23 ibtmp1
-rw-r----- 1 mysql mysql      123 Jul 16 02:09 master.info
drwxr-x--- 2 mysql mysql     4096 Jul 15 06:35 mysql
drwxr-x--- 2 mysql mysql     8192 Jul 15 05:52 performance_schema
-rw-r----- 1 mysql mysql       61 Jul 16 02:09 relay-log.info
drwxr-x--- 2 mysql mysql       48 Jul 15 06:50 shenzhen
drwxr-x--- 2 mysql mysql     8192 Jul 15 05:52 sys
-rw-r----- 1 mysql mysql       84 Jul 16 01:55 worker-relay-log.info.1
-rw-r----- 1 mysql mysql       84 Jul 16 01:55 worker-relay-log.info.2
-rw-r----- 1 mysql mysql       84 Jul 16 01:55 worker-relay-log.info.3
-rw-r----- 1 mysql mysql       84 Jul 16 01:55 worker-relay-log.info.4

[root@db02 /data/mysql/3306/data]# ls -l *relay*
-rw-r----- 1 mysql mysql  206 Jul 16 01:55 db02-relay-bin.000001 中继日志
-rw-r----- 1 mysql mysql 1282 Jul 16 02:05 db02-relay-bin.000002 中继日志
-rw-r----- 1 mysql mysql   48 Jul 16 01:55 db02-relay-bin.index 中继日志索引
-rw-r----- 1 mysql mysql   61 Jul 16 02:09 relay-log.info 线程读取中继日志的位置信息
-rw-r----- 1 mysql mysql   84 Jul 16 01:55 worker-relay-log.info.1
-rw-r----- 1 mysql mysql   84 Jul 16 01:55 worker-relay-log.info.2
-rw-r----- 1 mysql mysql   84 Jul 16 01:55 worker-relay-log.info.3
-rw-r----- 1 mysql mysql   84 Jul 16 01:55 worker-relay-log.info.4


[root@db02 /data/mysql/3306/data]# cat relay-log.info 
7
./db02-relay-bin.000002  #SQL线程读取中继日志的文件名信息
320                          #SQL线程读取中继日志的位置点信息
mysql-bin.000005
350
3600
4
1


8.解析SQL线程未解析的全部剩余relay-bin中继日志数据。
[root@db02 /data/mysql/3306/data]# mysqlbinlog --start-position=320 db02-relay-bin.000002 > /backup/sql/relay.sql

[root@db02 /data/mysql/3306/data]# mysqlbinlog --skip-gtids --start-position=320 db02-relay-bin.000002 > /backup/sql/relay.sql

[root@db02 ~]# ls -l /backup/sql/relay.sql
-rw-r--r-- 1 root root 3688 Jul 16 02:15 /backup/sql/relay.sql


9.找到破坏数据库的SQL语句，并从已解析的SQL语句中将其删除掉，这里使用的是"drop database app05"
[root@db02 ~]# egrep "drop database app05" /backup/sql/relay.sql
drop database app05
[root@db02 ~]# sed -i ‘/drop database app05/d‘ /backup/sql/relay.sql         
[root@db02 ~]# egrep "drop database app05" /backup/sql/relay.sql
[root@db02 ~]# egrep "^drop database app05" /backup/sql/relay.sql


10.将解析后并处理好的relay.sql数据文件恢复到延迟从库。
[root@db02 ~]# mysql -S /data/mysql/3306/mysql.sock -p < /backup/sql/relay.sql 
Enter password:

Slave [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| app                |
| app01              |
| app02              |
| app03              |
| app04              |
| app05              |
| mysql              |
| performance_schema |
| shenzhen           |
| sys                |
+--------------------+
11 rows in set (0.00 sec)

之前的删除的app05数据库已经恢复找回来了！！！

利用延迟从库恢复数据库完毕，此时还需要将此从库切换为主库，作为新主库对外提供用户访问。再对其他遭到破坏的主从数据库进行修复。
-------------------------------------------------------->OK



Slave [(none)]> start slave;
Query OK, 0 rows affected (0.01 sec)

Master [shenzhen]> use shenzhen;
Database changed
Master [shenzhen]> insert into t1(id) values(2);
Query OK, 1 row affected (0.01 sec)

Master [shenzhen]> select * from t1;
+------+
| id   |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.00 sec)

Slave [(none)]> stop slave;
Query OK, 0 rows affected (0.02 sec)

Slave [(none)]> change master to master_delay = 20;
Query OK, 0 rows affected (0.01 sec)

Slave [(none)]> start slave;
Query OK, 0 rows affected (0.03 sec)

Slave [(none)]> select * from shenzhen.t1;
+------+
| id   |
+------+
|    1 |
|    2 |
+------+
2 rows in set (0.00 sec)