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17.1 MySQL主从介绍
Mysql主从又叫Replication,AB复制。A、B两台机器做主从后，A上写数据，B上也会跟着写数据，A和B的数据实时同步。
Mysql的主从实现是基于binlog的，要开启binlog才能够实现主从功能。
Mysql主从的原理：3个步骤
1、主将更改操作记录到binlog里。
2、从将主的binlog事件（sql语句）同步到从的机器上，并记录在relaylog里（中继日志）。
3、根据relaylog里的sql语句，按顺序执行。
主上有一个logdump线程，用来与从的I/O线程传递binlog。
从上有两个线程，其中I/O线程用来同步主的binlog并生成relaylog，另一个线程是SQL线程把relaylog的SQL语句执行落地。
使用场景：
1、单独的数据备份：主机器宕机后，备份的从机器可以给Web服务提供数据
2、读备份库：web服务从主上读写数据，当主机器访问压力大的时候，可以在从上读数据，缓解主压力，但是从机器不写入数据。
17.2 准备工作
主机器A、从机器B上都安装Mysql：二进制免编译包安装
1、解压，初始化mysql：
[root@lgs-02 src]# tar zxvf mysql-5.6.36-linux-glibc2.5-x86_64.tar.gz
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/oracle.cfg
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/mysql.cfg
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/Adabas.cfg
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/empress.cfg
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/mysql-4.0.cfg
mysql-5.6.36-linux-glibc2.5-x86_64/sql-bench/limits/interbase.cfg
[root@lgs-02 src]# ls
mysql-5.6.36-linux-glibc2.5-x86_64 mysql-5.6.36-linux-glibc2.5-x86_64.tar.gz
[root@lgs-02 mysql]# ./scripts/mysql_install_db --user=mysql --datadir=/data/mysql/
Installing MySQL system tables...2018-05-23 18:44:50 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-05-23 18:44:50 0 [Note] Ignoring --secure-file-priv value as server is running with --bootstrap.
2018-05-23 18:44:50 0 [Note] ./bin/mysqld (mysqld 5.6.36) starting as process 1462 ...
2018-05-23 18:44:50 1462 [Note] InnoDB: Using atomics to ref count buffer pool pages
2018-05-23 18:45:07 1462 [Note] InnoDB: Shutdown completed; log sequence number 1625977
OK
Filling help tables...2018-05-23 18:45:07 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-05-23 18:45:07 0 [Note] Ignoring --secure-file-priv value as server is running with --bootstrap.
2018-05-23 18:45:07 0 [Note] ./bin/mysqld (mysqld 5.6.36) starting as process 1484 ...
2018-05-23 18:45:07 1484 [Note] InnoDB: Using atomics to ref count buffer pool pages
2018-05-23 18:45:07 1484 [Note] InnoDB: The InnoDB memory heap is disabled
2018-05-23 18:45:07 1484 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-05-23 18:45:07 1484 [Note] InnoDB: Memory barrier is not used
2018-05-23 18:45:07 1484 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-05-23 18:45:07 1484 [Note] InnoDB: Using Linux native AIO
2018-05-23 18:45:07 1484 [Note] InnoDB: Using CPU crc32 instructions
2018-05-23 18:45:07 1484 [Note] InnoDB: Initializing buffer pool, size = 128.0M
2018-05-23 18:45:07 1484 [Note] InnoDB: Completed initialization of buffer pool
2018-05-23 18:45:07 1484 [Note] InnoDB: Highest supported file format is Barracuda.
2018-05-23 18:45:07 1484 [Note] InnoDB: 128 rollback segment(s) are active.
2018-05-23 18:45:07 1484 [Note] InnoDB: Waiting for purge to start
2018-05-23 18:45:07 1484 [Note] InnoDB: 5.6.36 started; log sequence number 1625977
2018-05-23 18:45:07 1484 [Note] Binlog end
2018-05-23 18:45:07 1484 [Note] InnoDB: FTS optimize thread exiting.
2018-05-23 18:45:07 1484 [Note] InnoDB: Starting shutdown...
2018-05-23 18:45:09 1484 [Note] InnoDB: Shutdown completed; log sequence number 1625987
OK
To start mysqld at boot time you have to copy
support-files/mysql.server to the right place for your system
PLEASE REMEMBER TO SET A PASSWORD FOR THE MySQL root USER !
To do so, start the server, then issue the following commands:
./bin/mysqladmin -u root password 'new-password'
./bin/mysqladmin -u root -h lgs-02 password 'new-password'
2、启动mysqld服务，启动前：修改my.cnf配置文件的basedir、datadir，拷贝启动脚本（也要改脚本的basedir、datadir）
[root@lgs-02 mysql]# ls support-files/my-default.cnf
support-files/my-default.cnf
[root@lgs-02 mysql]# cp support-files/my-default.cnf /etc/my.cnf
cp：是否覆盖"/etc/my.cnf"？ y
[root@lgs-02 ~]# cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld
[root@lgs-02 ~]# ls -l /etc/init.d/mysqld
-rwxr-xr-x. 1 root root 10565 5月 23 19:23 /etc/init.d/mysqld
[root@lgs-02 ~]# vim !$
vim /etc/init.d/mysqld
basedir=/usr/local/mysql/
datadir=/data/mysql/
[root@lgs-02 ~]# /etc/init.d/mysqld start
Starting MySQL.Logging to '/data/mysql/lgs-02.err'.
............ SUCCESS!
17.3 配置主
1、修改my.cnf：设置服务id、定义binlog日志名字，重启mysqld
[root@lgs local]# vim /etc/my.cnf
log_bin=lgs01 //binlog日志文件的前缀，在/data/mysql/目录下生成 lgs01.index和lgs01.000001
server_id =130
[root@lgs local]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
2、创建一个库，恢复填充数据进去用作实验：zc01库
[root@lgs tmp]# mysqldump -uroot -p7826078 zrlog >/tmp/blog.sql //备份zrlog库到 /tmp/目录下
Warning: Using a password on the command line interface can be insecure.
[root@lgs tmp]# mysql -uroot -p7826078 -e "create database zc01" //创建zc01的库，用作实验
Warning: Using a password on the command line interface can be insecure.
[root@lgs tmp]# mysql -uroot -p7826078 zc01 use zc01;
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_zc01 |
+----------------+
| comment |
| link |
| log |
| lognav |
| plugin |
| tag |
| type |
| user |
| website |
+----------------+
9 rows in set (0.00 sec)
3、创建同步数据的用户:repl
mysql> grant replication slave on *.* to 'repl'@'192.168.87.132' identified by '7826078'; //指定来源ip的从机器的ip。
Query OK, 0 rows affected (0.00 sec)
mysql> flush tables with read lock; //锁表，不让继续写数据
Query OK, 0 rows affected (0.02 sec)
mysql> show master status; //记住file和Position的内容，从机器配置的时候要用到。
+--------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+--------------+----------+--------------+------------------+-------------------+
| lgs01.000001 | 35637 | | | |
+--------------+----------+--------------+------------------+-------------------+
1 row in set (0.01 sec)
[root@lgs tmp]# ls -l /data/mysql/ //主机器上的库文件，一会同步zc01库。
总用量 110820
-rw-rw----. 1 mysql mysql 56 4月 17 18:58 auto.cnf
-rw-rw----. 1 mysql mysql 12582912 6月 28 23:27 ibdata1
-rw-rw----. 1 mysql mysql 50331648 6月 28 23:27 ib_logfile0
-rw-rw----. 1 mysql mysql 50331648 4月 17 18:47 ib_logfile1
-rw-rw---- 1 mysql mysql 35637 6月 28 23:43 lgs01.000001
-rw-rw----. 1 mysql mysql 130455 5月 10 08:12 lgs-01.err
-rw-rw---- 1 mysql mysql 15 6月 28 22:16 lgs01.index
-rw-rw---- 1 mysql mysql 43229 6月 28 22:16 lgs.err
-rw-rw---- 1 mysql mysql 5 6月 28 22:16 lgs.pid
drwx------. 2 mysql mysql 4096 4月 17 18:47 mysql
drwx------. 2 mysql mysql 4096 4月 17 18:47 performance_schema
drwx------. 2 mysql mysql 6 4月 17 18:47 test
drwx------ 2 mysql mysql 324 6月 28 23:27 zc01
4、备份zc01库文件，拷贝到从机器上去：在从上新建库，用zc01库文件数据恢复到新建的库中去。
[root@lgs tmp]# mysqldump -uroot -p7826078 zc01 >/tmp/zc01.sql
Warning: Using a password on the command line interface can be insecure.
[root@lgs tmp]# ls -l zc01.sql
-rw-r--r-- 1 root root 34508 6月 28 23:51 zc01.sql
17.4 配置从
1、修改my.cnf文件：设置服务id，与主的服务id不一样。重启mysqld
[root@lgs-02 tmp]# vim /etc/my.cnf
[mysqld]
server_id =131
[root@lgs-02 tmp]# /etc/init.d/mysqld restart
Shutting down MySQL.. SUCCESS!
Starting MySQL. SUCCESS!
2、把主上的zc01.sql库文件拷贝到从上：放/tmp/目录下
3、创建一个库，把zc01的数据恢复进去
mysql> create database zc01; //创建新库zc01
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| zc01 |
+--------------------+
5 rows in set (0.01 sec)
mysql> quit
Bye
[root@lgs-02 tmp]# mysql -uroot -p7826078 zc01 4、实现主从：
mysql> stop slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> change master to master_host='192.168.87.130',master_user='repl',master_password='7826078',master_log_file='lgs01.000001',master_log_pos=35637; //配置主信息
Query OK, 0 rows affected, 2 warnings (0.05 sec)
mysql> start slave; //打开主从同步
Query OK, 0 rows affected (0.02 sec)
5、检测是否成功配置主从：Slave_IO_Running: Yes和Slave_SQL_Running: Yes 就代表成功配置
mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.87.130
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: lgs01.000001
Read_Master_Log_Pos: 35637
Relay_Log_File: lgs-02-relay-bin.000003
Relay_Log_Pos: 279
Relay_Master_Log_File: lgs01.000001
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: 35637
Relay_Log_Space: 612
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: 130
Master_UUID: 40e65727-422e-11e8-8d14-000c29d0e2b8
Master_Info_File: /data/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
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
1 row in set (0.00 sec)
如果Slave_IO_Running: Connectting. 把主上的firewalld、selinux关掉再打开同步。
6、主机器上：解锁表。
mysql> unlock tables;
Query OK, 0 rows affected (0.01 sec)
7、关注这些主从的状态：
Seconds_Behind_Master: 0 //延时
Last_IO_Errno: 0 //io线程错误
Last_IO_Error:
Last_SQL_Errno: 0 //执行sql错误
Last_SQL_Error:
17.5 测试主从同步
主机器上写入数据，看能否同步到从机器上。
测试前，可以自定义几个主从相关的参数:my.cnf
## 主机器上的配置
[root@lgs tmp]# vim /etc/my.cnf
[mysqld]
binlog_do_db= //仅同步指定的库，多个库用逗号分隔
binlog_ignore_db= //忽略指定库，剩余的都同步。
##从机器上的配置
Replicate_do_db=
Replicate_ignore_db=
Replicate_do_table=
Replicate_ignore_table=
Replicate_wild_do_table=
Replicate_wild_ignore_table=
开始测试：
##主上
mysql> use zc01;
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_zc01 |
+----------------+
| comment |
| link |
| log |
| lognav |
| plugin |
| tag |
| type |
| user |
| website |
+----------------+
9 rows in set (0.00 sec)
mysql> select count(*) user;
+------+
| user |
+------+
| 1 |
+------+
1 row in set (0.01 sec)
mysql> select count(*) comment;
+---------+
| comment |
+---------+
| 1 |
+---------+
1 row in set (0.00 sec)
##从上
mysql> use zc01;
Database changed
mysql> show tables;
+----------------+
| Tables_in_zc01 |
+----------------+
| comment |
| link |
| log |
| lognav |
| plugin |
| tag |
| type |
| user |
| website |
+----------------+
9 rows in set (0.00 sec)
mysql> select count(*) user;
+------+
| user |
+------+
| 1 |
+------+
1 row in set (0.01 sec)
mysql> select count(*) comment;
+---------+
| comment |
+---------+
| 1 |
+---------+
1 row in set (0.00 sec)
mysql> select count(*) website;
+---------+
| website |
+---------+
| 1 |
+---------+
1 row in set (0.01 sec)
主上删除comment表的数据：再看看从的comment表是否也会0行
mysql> drop table comment;
Query OK, 0 rows affected (0.02 sec)
mysql> show tables;
+----------------+
| Tables_in_zc01 |
+----------------+
| link |
| log |
| lognav |
| plugin |
| tag |
| type |
| user |
| website |
+----------------+
8 rows in set (0.00 sec)
从上查询comment表的时候就报错不存在表了：证明从上同步主的操作了。
mysql> select * from comment;
ERROR 1146 (42S02): Table 'zc01.comment' doesn't exist