什么是·Mysql/Mariadb主從復(fù)制？
Mysql/Mariadb主從復(fù)制：當(dāng)Master（主）數(shù)據(jù)庫發(fā)生變化的時候，變化實時會同步到slave（從）數(shù)據(jù)庫中；類似于：Samba共享文件（C/S）、NFS網(wǎng)絡(luò)文件共享（C/S），當(dāng)服務(wù)端（Server）發(fā)生變化時，客戶端（client）數(shù)據(jù)內(nèi)容會根據(jù)服務(wù)端進(jìn)行改變；
在master機器上，主從同步事件會被寫到特殊的log文件中(binary-log);
主從同步事件有3種形式:statement、row、mixed。
statement：會將對數(shù)據(jù)庫操作的sql語句寫入到binlog中。 row：會將每一條數(shù)據(jù)的變化寫入到binlog中。 mixed：statement與row的混合。Mysql決定什么時候?qū)憇tatement格式的，什么時候?qū)憆ow格式的binlog。
整體上來說，復(fù)制有3個步驟：
下面這章圖可以詳細(xì)解釋其原理：
說的簡單一些就是：
當(dāng)對Master數(shù)據(jù)庫不管做了增、刪、改還是創(chuàng)建了數(shù)據(jù)庫、表等操作時，Slave就會快速的接受這些數(shù)據(jù)以及對象的操作，從而實現(xiàn)主從數(shù)據(jù)復(fù)制，保證數(shù)據(jù)的一致性?！ ?/pre>
我記得我學(xué)PHP開發(fā)的時候，教員經(jīng)常說的一句話就是：學(xué)習(xí)半小時，實戰(zhàn)一分鐘；
好了，接下來到我們實戰(zhàn)的時刻了，認(rèn)真聽講喲！！！
系統(tǒng)環(huán)境：系統(tǒng)基本上都差不多，一般多數(shù)都是Linux平臺和Windows平臺比較多，不管什么樣的系統(tǒng)環(huán)境對這次實戰(zhàn)的操作都影響不大，我在這里使用的是Docker虛擬出來的CentOS操作系統(tǒng)，當(dāng)然您可以選用Ubuntu、RedHat以及Windows系統(tǒng)，這些都不會影響到大的操作；
我這里使用的系統(tǒng)版本：
[root@master /]# cat /etc/redhat-releaseCentOS Linux release 8.0.1905 (Core)
這里會用到兩臺服務(wù)器：其中一臺MasterIP172.18.0.2，另外一個slaveIP172.18.0.3
數(shù)據(jù)庫版本：（我這里使用的Mariadb，你可以使用mysql數(shù)據(jù)庫）
[root@master /]# mysql --versionmysql Ver 15.1 Distrib 10.3.11-MariaDB, for Linux (x86_64) using readline 5.1
配置Master數(shù)據(jù)庫
1.更改Master配置文件
找到下面文件：
mysql數(shù)據(jù)庫：/etc/mysql/mysql,conf.d/mysqld.cnfmariadb數(shù)據(jù)庫：/etc/my.cnf.d/mariadb.cnf
注意：我這里是使用yum進(jìn)行安裝的所以默認(rèn)配置文件是在/etc下面，建議在修改上面兩個文件時要先將配置文件進(jìn)行備份
修改以下配置：
bind-address=172.18.0.2\\指定Master地址server-id = 1\\指定唯一的serverid部分版本沒有需手動寫入log_bin = /var/log/mariadb/mariadb-bin.log\\開啟binlog部分版本沒有需手動寫入
注意：log_bin這個字段需根據(jù)實際情況來定，需找到數(shù)據(jù)庫的日志文件，默認(rèn)實在 /var/log
2.重新啟動數(shù)據(jù)庫
[root@master my.cnf.d]# systemctl restart mariadb\\centos7、centos8、ubuntu重新啟動方式[root@master my.cnf.d]# server mariadb restart\\centos6及以下版本使用這個重新啟動方式
mysql重新啟動：
[root@master my.cnf.d]# systemctl restart mysqld\\centos7、centos8、ubuntu重新啟動方式[root@master my.cnf.d]# server mysqld restart\\centos6及以下版本使用這個重新啟動方式
3.初始化數(shù)據(jù)庫
[root@master my.cnf.d]# mysql_secure_installation NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!In order to log into MariaDB to secure it, we'll need the currentpassword for the root user. If you've just installed MariaDB, andyou haven't set the root password yet, the password will be blank,so you should just press enter here.Enter current password for root (enter for none): //這里敲回車OK, successfully used password, moving on...Setting the root password ensures that nobody can log into the MariaDBroot user without the proper authorisation.Set root password? [Y/n] y//這里是設(shè)置root密碼，可不進(jìn)行設(shè)置New password: //新密碼Re-enter new password: //舊密碼Password updated successfully!Reloading privilege tables.. ... Success!By default, a MariaDB installation has an anonymous user, allowing anyoneto log into MariaDB without having to have a user account created forthem. This is intended only for testing, and to make the installationgo a bit smoother. You should remove them before moving into aproduction environment.Remove anonymous users? [Y/n] y ... Success!Normally, root should only be allowed to connect from 'localhost'. Thisensures that someone cannot guess at the root password from the network.Disallow root login remotely? [Y/n] y ... Success!By default, MariaDB comes with a database named 'test' that anyone canaccess. This is also intended only for testing, and should be removedbefore moving into a production environment.Remove test database and access to it? [Y/n] y - Dropping test database... ... Success! - Removing privileges on test database... ... Success!Reloading the privilege tables will ensure that all changes made so farwill take effect immediately.Reload privilege tables now? [Y/n] y ... Success!Cleaning up...All done! If you've completed all of the above steps, your MariaDBinstallation should now be secure.Thanks for using MariaDB![root@master my.cnf.d]#
4.創(chuàng)建主從同步的用戶
[root@master ~]# mysql -u root -p\\登陸數(shù)據(jù)庫Enter password: \\輸入root密碼Welcome to the MariaDB monitor. Commands end with ; or \g.Your MariaDB connection id is 18Server version: 10.3.11-MariaDB-log MariaDB ServerCopyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MariaDB [(none)]> GRANT REPLICATION SLAVE on *.* to 'slave'@'%' IDENTIFIED BY 'redhat';\\創(chuàng)建用戶，并設(shè)置相應(yīng)的權(quán)限\\此處%表示允許從任何地方（除本地外）使用此賬號進(jìn)行登陸使用，在正式環(huán)境建議具體到某臺主機IPQuery OK, 0 rows affected (0.000 sec)\\表示sql語句執(zhí)行成功
5.更新Slave用戶權(quán)限
MariaDB [(none)]> flush privileges;\\每次修改用戶權(quán)限，都要使用這個sql語句進(jìn)行更新Query OK, 0 rows affected (0.000 sec)
6.導(dǎo)出數(shù)據(jù)庫中所有數(shù)據(jù)（此步驟取決于slave的權(quán)限）
[root@master ~]# mysqldump -u root -p --all-databases --master-data > mariadb.bat.sql--all-databases\\此參數(shù)表示備份所有數(shù)據(jù)庫--master-data\\此參數(shù)表示將二進(jìn)制的信息寫入到輸出文件中，在這里是寫入到備份的sql文件中Enter password:
7.查看MASTERr REPLICATION LOG位置
MariaDB [(none)]> show master status;+--------------------+----------+--------------+------------------+| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |+--------------------+----------+--------------+------------------+| mariadb-bin.000002 | 1974 | | |+--------------------+----------+--------------+------------------+1 row in set (0.000 sec)
配置Slave數(shù)據(jù)庫
1.更改Slave配置文件
文件位置與Master位置一致
mysql數(shù)據(jù)庫：/etc/mysql/mysql,conf.d/mysqld.cnfmariadb數(shù)據(jù)庫：/etc/my.cnf.d/mariadb.cnf
注意：我這里是使用yum進(jìn)行安裝的所以默認(rèn)配置文件是在/etc下面，建議在修改上面兩個文件時要先將配置文件進(jìn)行備份
修改以下配置：
bind-address=172.18.0.3\\指定Master地址server-id = 2\\指定唯一的serverid部分版本沒有需手動寫入log_bin = /var/log/mariadb/mariadb-bin.log\\開啟binlog部分版本沒有需手動寫入
注意：log_bin這個字段需根據(jù)實際情況來定，需找到數(shù)據(jù)庫的日志文件，默認(rèn)實在 /var/log
2.重新啟動數(shù)據(jù)庫
[root@master my.cnf.d]# systemctl restart mariadb\\centos7、centos8、ubuntu重新啟動方式[root@master my.cnf.d]# server mariadb restart\\centos6及以下版本使用這個重新啟動方式
mysql重新啟動：
[root@master my.cnf.d]# systemctl restart mysqld\\centos7、centos8、ubuntu重新啟動方式[root@master my.cnf.d]# server mysqld restart\\centos6及以下版本使用這個重新啟動方式
3.初始化數(shù)據(jù)庫
[root@master my.cnf.d]# mysql_secure_installation NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!In order to log into MariaDB to secure it, we'll need the currentpassword for the root user. If you've just installed MariaDB, andyou haven't set the root password yet, the password will be blank,so you should just press enter here.Enter current password for root (enter for none): //這里敲回車OK, successfully used password, moving on...Setting the root password ensures that nobody can log into the MariaDBroot user without the proper authorisation.Set root password? [Y/n] y//這里是設(shè)置root密碼，可不進(jìn)行設(shè)置New password: //新密碼Re-enter new password: //舊密碼Password updated successfully!Reloading privilege tables.. ... Success!By default, a MariaDB installation has an anonymous user, allowing anyoneto log into MariaDB without having to have a user account created forthem. This is intended only for testing, and to make the installationgo a bit smoother. You should remove them before moving into aproduction environment.Remove anonymous users? [Y/n] y ... Success!Normally, root should only be allowed to connect from 'localhost'. Thisensures that someone cannot guess at the root password from the network.Disallow root login remotely? [Y/n] y ... Success!By default, MariaDB comes with a database named 'test' that anyone canaccess. This is also intended only for testing, and should be removedbefore moving into a production environment.Remove test database and access to it? [Y/n] y - Dropping test database... ... Success! - Removing privileges on test database... ... Success!Reloading the privilege tables will ensure that all changes made so farwill take effect immediately.Reload privilege tables now? [Y/n] y ... Success!Cleaning up...All done! If you've completed all of the above steps, your MariaDBinstallation should now be secure.Thanks for using MariaDB![root@master my.cnf.d]#
4.從Master將數(shù)據(jù)庫備份復(fù)制到slave服務(wù)器
[root@slave my.cnf.d]# scp jia@172.18.0.2:/opt/mariadb.bat.sql /opt/jia@172.18.0.2's password: mariadb.bat.sql
5.將備份數(shù)據(jù)恢復(fù)到slave數(shù)據(jù)庫
[root@slave my.cnf.d]# mysql -u root -p < /opt/mariadb.bat.sql Enter password:
6.使slave與master建立連接
[root@slave my.cnf.d]# mysql -u root -pEnter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)[root@slave my.cnf.d]# mysql -u root -pEnter password: Welcome to the MariaDB monitor. Commands end with ; or \g.Your MariaDB connection id is 22Server version: 10.3.11-MariaDB-log MariaDB ServerCopyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.MariaDB [(none)]> stop slave;Query OK, 0 rows affected, 1 warning (0.000 sec)MariaDB [(none)]> CHANGE MASTER TO -> MASTER_HOST = '172.18.0.2',\\指定Master數(shù)據(jù)庫地址 -> MASTER_USER = 'slave',\\指定主從復(fù)制用戶名 -> MASTER_PASSWORD = 'redhat',\\指定主從復(fù)制用戶密碼 -> MASTER_LOG_FILE = 'mariadb-bin.000002',\\指定Master數(shù)據(jù)庫的binlog文件名 -> MASTER_LOG_POS=1974;Query OK, 0 rows affected (0.290 sec)MariaDB [(none)]> start slave;\\開啟復(fù)制功能Query OK, 0 rows affected (0.019 sec)MariaDB [(none)]>
注意：lMASTER_LOG_FILE='mariadb-bin.000002與MASTER_LOG_POS=1974的值，是從上面的 SHOW MASTER STATUS 得到的。
到這里已經(jīng)可以做到主從復(fù)制了下面讓我們測試一下吧
測試方法很簡單，只需要在主數(shù)據(jù)庫上面創(chuàng)建數(shù)據(jù)庫或者增加一條記錄就可以測試是否主從復(fù)制配置成功
MariaDB [(none)]> show databases;+--------------------+| Database |+--------------------+| information_schema || mysql || performance_schema |+--------------------+3 rows in set (0.018 sec)MariaDB [(none)]> create database a;\\在主數(shù)據(jù)庫創(chuàng)建a數(shù)據(jù)庫Query OK, 1 row affected (0.063 sec)MariaDB [(none)]> show databases;+--------------------+| Database |+--------------------+| a || information_schema || mysql || performance_schema |+--------------------+4 rows in set (0.000 sec)
下面我們來看看從數(shù)據(jù)庫上面有沒有a這個數(shù)據(jù)庫吧
MariaDB [(none)]> show databases;+--------------------+| Database |+--------------------+| a || information_schema || mysql || performance_schema |+--------------------+4 rows in set (0.075 sec)
我們會發(fā)現(xiàn)已經(jīng)有了a這個數(shù)據(jù)庫
