基于GTID的復制
簡介
基于GTID的復制是MySQL 5.6后新增的復制方式.
GTID (global transaction identifier) 即全局事務ID, 保證了在每個在主庫上提交的事務在集群中有一個唯一的ID.
在原來基于日志的復制中, 從庫需要告知主庫要從哪個偏移量進行增量同步, 如果指定錯誤會造成數據的遺漏, 從而造成數據的不一致.
而基于GTID的復制中, 從庫會告知主庫已經執行的事務的GTID的值, 然后主庫會將所有未執行的事務的GTID的列表返回給從庫. 并且可以保證同一個事務只在指定的從庫執行一次.
實戰
1、在主庫上建立復制賬戶并授予權限
基于GTID的復制會自動地將沒有在從庫執行的事務重放, 所以不要在其他從庫上建立相同的賬號. 如果建立了相同的賬戶, 有可能造成復制鏈路的錯誤.
mysql/32296.html">mysql> create user 'repl'@'172.%' identified by '123456';
注意在生產上的密碼必須依照相關規范以達到一定的密碼強度, 并且規定在從庫上的特定網段上才能訪問主庫.
mysql> grant replication slave on *.* to 'repl'@'172.%';
查看用戶
mysql> select user, host from mysql.user;+-----------+-----------+| user | host |+-----------+-----------+| prontera | % || root | % || mysql.sys | localhost || root | localhost |+-----------+-----------+4 rows in set (0.00 sec)
查看授權
mysql> show grants for repl@'172.%';+--------------------------------------------------+| Grants for repl@172.% |+--------------------------------------------------+| GRANT REPLICATION SLAVE ON *.* TO 'repl'@'172.%' |+--------------------------------------------------+1 row in set (0.00 sec)
2、配置主庫服務器
[mysqld]log_bin = /var/log/mysql/mysql-binlog_bin_index = /var/log/mysql/mysql-bin.indexbinlog_format = rowserver_id = 101gtid_mode = ONenforce_gtid_consistency = ON#log_slave_updates = ON
NOTE: 把日志與數據分開是個好習慣, 最好能放到不同的數據分區
enforce_gtid_consistency 強制GTID一致性, 啟用后以下命令無法再使用
create table ... select ...
mysql> create table dept select * from departments;ERROR 1786 (HY000): Statement violates GTID consistency: CREATE TABLE ... SELECT.
因為實際上是兩個獨立事件, 所以只能將其拆分先建立表, 然后再把數據插入到表中
create temporary table
事務內部不能創建臨時表
mysql> begin;Query OK, 0 rows affected (0.00 sec)mysql> create temporary table dept(id int);ERROR 1787 (HY000): Statement violates GTID consistency: CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE can only be executed outside transactional context. These statements are also not allowed in a function or trigger because functions and triggers are also considered to be multi-statement transactions.
同一事務中更新事務表與非事務表(MyISAM)
mysql> CREATE TABLE `dept_innodb` (id INT(11) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT);Query OK, 0 rows affected (0.04 sec)mysql> CREATE TABLE `dept_myisam` (id INT(11) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT) ENGINE = `MyISAM`;Query OK, 0 rows affected (0.03 sec)mysql> begin;Query OK, 0 rows affected (0.00 sec)mysql> insert into dept_innodb(id) value(1);Query OK, 1 row affected (0.00 sec)mysql> insert into dept_myisam(id) value(1);ERROR 1785 (HY000): Statement violates GTID consistency: Updates to non-transactional tables can only be done in either autocommitted statements or single-statement transactions, and never in the same statement as updates to transactional tables.
所以建議選擇Innodb作為默認的數據庫引擎.
log_slave_updates 該選項在MySQL 5.6版本時基于GTID的復制是必須的, 但是其增大了從服務器的IO負載, 而在MySQL 5.7中該選項已經不是必須項
3、配置從庫服務器
master_info_repository 與relay_log_info_repository
在MySQL 5.6.2之前, slave記錄的master信息以及slave應用binlog的信息存放在文件中, 即master.info與relay-log.info. 在5.6.2版本之后, 允許記錄到table中. 對應的表分別為mysql.slave_master_info與mysql.slave_relay_log_info, 且這兩個表均為innodb引擎表.
[mysqld]log_bin = /var/log/mysql/mysql-binlog_bin_index = /var/log/mysql/mysql-bin.indexserver_id = 102# slavesrelay_log = /var/log/mysql/relay-binrelay_log_index = /var/log/mysql/relay-bin.indexrelay_log_info_file = /var/log/mysql/relay-bin.infoenforce_gtid_consistency = ONlog_slave_updates = ONread_only = ONmaster_info_repository = TABLErelay_log_info_repository = TABLE
4、從庫數據初始化 - [optional]
先在主庫上備份數據
—master-data=2 該選項將當前服務器的binlog的位置和文件名追加到輸出文件中(show master status). 如果為1, 將偏移量拼接到CHANGE MASTER 命令. 如果為2, 輸出的偏移量信息將會被注釋。
--all-databases 因為基于GTID的復制會記錄全部的事務, 所以要構建一個完整的dump這個選項是推薦的
常見錯誤
當從庫導入SQL的時候出現
此時進入從庫的MySQL Command Line, 使用reset master即可
5、啟動基于GTID的復制
現有master@172.20.0.2和slave@172.20.0.3, 并且已經通過mysqldump將數據同步至從庫slave中. 現在在從服務器slave上配置復制鏈路
mysql> change master to master_host='master', master_user='repl', master_password='123456', master_auto_position=1;Query OK, 0 rows affected, 2 warnings (0.06 sec)
啟動復制
mysql> start slave;
啟動成功后查看slave的狀態
mysql> show slave status/G*************************** 1. row *************************** Slave_IO_State: Queueing master event to the relay log Master_Host: master Master_User: repl Master_Port: 3306 Connect_Retry: 60 Master_Log_File: mysql-bin.000002 Read_Master_Log_Pos: 12793692 Relay_Log_File: relay-bin.000002 Relay_Log_Pos: 1027 Relay_Master_Log_File: mysql-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: 814 Relay_Log_Space: 12794106 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: 5096Master_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: 101 Master_UUID: a9fd4765-ec70-11e6-b543-0242ac140002 Master_Info_File: mysql.slave_master_info SQL_Delay: 0 SQL_Remaining_Delay: NULL Slave_SQL_Running_State: Reading event from the relay log Master_Retry_Count: 86400 Master_Bind: Last_IO_Error_Timestamp: Last_SQL_Error_Timestamp: Master_SSL_Crl: Master_SSL_Crlpath: Retrieved_Gtid_Set: a9fd4765-ec70-11e6-b543-0242ac140002:1-39 Executed_Gtid_Set: a9fd4765-ec70-11e6-b543-0242ac140002:1-4 Auto_Position: 1 Replicate_Rewrite_DB: Channel_Name: Master_TLS_Version:1 row in set (0.00 sec)
當Slave_IO_Running, Slave_SQL_Running為YES,
且Slave_SQL_Running_State 為Slave has read all relay log; waiting for more updates時表示成功構建復制鏈路
6、總結
優點
缺點
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持VeVb武林網。
新聞熱點
疑難解答
