主從架構介紹
mysql自帶的副本機制允許從一個mysql數(shù)據(jù)庫（稱之為主或者源庫）復制一個或多個mysql數(shù)據(jù)庫（稱之為從或者副本庫）。副本機制默認情況下是異步進行的伯病，不需要永久連接從源庫接收更新。副本機制作用的范圍可以為所有數(shù)據(jù)庫否过，選定的數(shù)據(jù)庫或者選定的表午笛。
MySQL 8.0支持不同的兩種復制方法：
1）基于從源庫的二進制日志（binary log）復制事件實現(xiàn)惭蟋，并要求在源庫和副本庫之間同步日志文件和日志文件中的位置，異步實現(xiàn)药磺，不具有事務性告组。
mysql-replication-based-on-binary-log.png
2）基于全局事務標識符(GTIDs)實現(xiàn)，具有事務性癌佩，因此不需要處理日志文件及其位置木缝，這極大地簡化了許多常見的復制任務。只要在源庫上提交的所有事務也應用于副本庫上围辙，使用GTIDs的復制就可以保證源和副本之間的一致性我碟。
主從架構優(yōu)點
- 可以實現(xiàn)讀寫分離架構，對主庫進行寫酌畜，對從庫進行讀怎囚，可以工作負載到副本庫進而提高整體性能。
- 可以保障數(shù)據(jù)安全桥胞，因為副本可以暫停復制過程恳守，所以可以在副本上運行備份服務，而不會損壞相應的源數(shù)據(jù)贩虾。
- 可以實現(xiàn)數(shù)據(jù)的備份催烘，實現(xiàn)容災
基于binary log的主從架構實踐
主庫設置
首先在在 MySQL 中增加一個可以進行主從復制權限的用戶。在 mysql 交互環(huán)境中執(zhí)行如下命令
# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 8.0.13 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> create user 'repl'@'10.20.131.38' identified by 'Inspur123!@#';
Query OK, 0 rows affected (0.07 sec)
mysql> grant replication slave on *.* to 'repl'@'10.20.131.38';
Query OK, 0 rows affected (0.05 sec)
mysql> show master status;
+---------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+---------------+----------+--------------+------------------+-------------------+
| binlog.000001 | 2324 | | | |
+---------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
mysql>
命令**show master status **獲取到當前歸檔日志的名字和位置缎罢，后面從服務器設置主從復制的時候需要從這個位置開始伊群。
從庫設置
# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 8.0.13 MySQL Community Server - GPL
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> change master to
-> master_host='10.20.131.37',
-> master_port=3306,
-> master_user='repl',
-> master_password='Test123!@#',
-> master_log_file='binlog.000001',
-> master_log_pos=2324;
Query OK, 0 rows affected, 2 warnings (0.07 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 10.20.131.37
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: binlog.000001
Read_Master_Log_Pos: 2324
Relay_Log_File: h10p20p131p38-relay-bin.000002
Relay_Log_Pos: 319
Relay_Master_Log_File: binlog.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: 2324
Relay_Log_Space: 535
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: 37
Master_UUID: 109ae7ea-1d7c-11eb-980d-48f97cff3ddf
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:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
Master_public_key_path:
Get_master_public_key: 0
1 row in set (0.00 sec)
ERROR:
No query specified
Slave_IO_State 的值為 Waiting for master to send event ，表示已經(jīng)準備好接受主庫發(fā)送過來的歸檔日志進行處理了策精。
測試主從復制
主庫建立名字為test的database舰始，如下：
mysql> create database test default character set utf8;
Query OK, 1 row affected, 1 warning (0.03 sec)
從庫確認是否已經(jīng)同步備份，如下：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)
mysql>
根據(jù)以上輸出咽袜，可以確認主從復制已經(jīng)生效丸卷。
