MySQL示例DTID主从原理解析

吾爱主题阅读：137 2024-04-02 08:05:25 评论：0

1.GTID基本概念

MySQL 5.6.5开始支持的，全局事务标识符（GTID（Global Transaction ID））是创建的唯一标识符，并与在源（主）服务器上提交的每个事务相关联。
此标识符不但是唯一的，而且在给定复制设置中的所有服务器上都是唯一的。
所有交易和所有GTID之间都有一对一的映射关系。
它由服务器ID以及事务ID组合而成。
这个全局事务ID不仅仅在原始服务器上唯一，在所有存在主从关系的mysql服务器上也是唯一的。
正是因为这样一个特性使得mysql的主从复制变得更加简单，以及数据库一致性更可靠。
一个GTID在一个服务器上只执行一次，避免重复执行导致数据混乱或者主从不一致。

2.GTID优点

保证同一个事务在某slave上绝对只执行一次，没有执行过的gtid事务总是会被执行。
不用像传统复制那样保证binlog的坐标准确，因为根本不需要binlog以及坐标。
故障转移到新的master的时候很方便，简化了很多任务。
很容易判断master和slave的数据是否一致。只要master上提交的事务在slave上也提交了，那么一定是一致的。

3.GTID的工作原理

1.当一个事务在主库端执行并提交时，产生GTID，一同记录到binlog日志中。
2.binlog传输到slave,并存储到slave的relaylog后，读取这个GTID的这个值设置gtid_next变量，即告诉Slave，下一个要执行的GTID值。
3、sql线程从relay log中获取GTID，然后对比slave端的binlog是否有该GTID。
4、如果有记录，说明该GTID的事务已经执行，slave会忽略。
5、如果没有记录，slave就会执行该GTID事务，并记录该GTID到自身的binlog，在读取执行事务前会先检查其他session持有该GTID，确保不被重复执行。
6、在解析过程中会判断是否有主键，如果有就用二级索引，如果没有就用全部扫描。

4.GTID比传统复制的优势

1.更简单的实现故障转移（failover），不需要找log_file,log_pos

2.更简单的搭建主从复制

3.更加安全

4.GTID是连续没有空洞的，因此主数据库发生冲突时，可以添加空事件的方式进行跳过

5.启动的方法

方法一：如果是新搭建的服务器，直接启动即可
方法二：如果是以及跑的服务器，需要重启一下mysql server

启动前，先关闭master的写入，保证master端和slave端数据保持同步，所有slave需要加上skip_slave_start=1的配置参数，避免启动后还是使用之前的复制协议

6.GTID(一主一从)配置

6.1环境：

centos8.0 ip：192.168.136.239 有数据 hostname：mysql01

centos8.0 ip：192.168.136.219 无数据 hostname：mysql02

#二进制安装以及mysql自启动服务略

6.2在主库上给从库授权：

mysql> grant replication slave on *.* to 'slave'@'192.168.136.219' identified by 'slave';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
#俩服务器均关闭防火墙
[root@mysql01 ~]# systemctl stop firewalld
[root@mysql01 ~]# setenforce 0
[root@mysql02 ~]# systemctl stop firewalld
[root@mysql02 ~]# setenforce 0
从库测试连接：
[root@mysql02 ~]# mysql -u slave -p'slave' -h192.168.136.239
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>

6.3确保数据一致操作

1.对主库进行锁表
mysql> flush tables with read lock;
2.对主库进行全备
[root@mysql01 ~]# mysqldump -uroot -A > /clq/all-databases-20210519.sql
3.拷贝到从库主机上去
[root@mysql01 ~]# scp /clq/all-databases-20210519.sql root@192.168.136.219:/backup/
[root@mysql02 backup]# ll
-rw-r--r--. 1 root root 873527 5月 19 16:40 all-databases-20210519.sql
4.从库上进行主库的恢复
[root@mysql02 backup]# mysql -uroot -pHuawei0917@ < all-databases-20210519.sql

6.4配置主库

[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
#skip-grant-tables
log-bin = master_bin #开启主库日志
server-id = 10 #服务唯一标识id
gtid-mode = on #GTID模式开启
enforce_gtid_consistency = on #强制gtid模式一致性
log-slave-updates = 1 #从库允许更新日志，同步操作日志
binlog_format = row #binlog日志格式为行格式, 默认是mixed混合模式
skip_slave_start = 1 #跳过从库开启，以主库开始开启
#重启
systemctl restart mysqld

6.5配置从库

[root@mysql02 data]# cat /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
#skip-grant-tables
gtid_mode=on
enforce_gtid_consistency=on
server-id=20
log-bin=slave_binlog #开启从库日志
log_slave-updates=1 #从库允许更新
binlog_format=row #格式为行
skip-slave_start=1
#重启
systemctl restart mysqld

查看gtid状态情况

mysql> show variables like '%gtid%';
+----------------------------------+-----------+
| Variable_name | Value |
+----------------------------------+-----------+
| binlog_gtid_simple_recovery | ON |
| enforce_gtid_consistency | ON |
| gtid_executed_compression_period | 1000 |
| gtid_mode | ON |
| gtid_next | AUTOMATIC |
| gtid_owned | |
| gtid_purged | |
| session_track_gtids | OFF |
+----------------------------------+-----------+
8 rows in set (0.00 sec)

6.6配置主从复制

#从库上root登录配置 #help change master to 可以查看帮助文档实例
mysql> change master to
-> master_host='192.168.136.239',
-> master_user='slave',
-> master_password='slave',
-> master_port=3306, #主库端口
-> master_auto_position=1; #位置
#master_use_gtid = current_pos
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
mysql> show slave status\G;
Slave_IO_Running: Connecting
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
保证系统一致性
授权一致性

（一主一从GTID）测试：

主库创建一个数据库test，进行测试查看

从库创建一个数据库test02，进行测试查看

#主库创建一个test数据库
mysql> create database test;
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
#从库上查看同步情况
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
6 rows in set (0.00 sec)
#从库创建test02库
mysql> create database test02;
Query OK, 1 row affected (0.00 sec)
#主库上查看
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys | #是没有test02库的
| test |
+--------------------+
5 rows in set (0.00 sec)

小结：主库上的数据操作会同步到从库上面去，而从库上的数据操作与主库没联系

7.GTID（一主俩从）

第三台mysql连接的话，相应配置

第3台mysql ，版本:centos8 ip:192.168.136.230 主机名:mysql03

[root@mysql03 ~]# cat /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
#skip-grant-tables
# replication config
log-bin = master_bin
server-id = 21 #id必须与之前不同
gtid-mode = on
enforce-gtid-consistency = on
log-slave-updates = 1
binlog-format = row
skip-slave-start = 1
#查看gtid情况
mysql> show variables like '%gtid%';
+----------------------------------+-----------+
| Variable_name | Value |
+----------------------------------+-----------+
| binlog_gtid_simple_recovery | ON |
| enforce_gtid_consistency | ON |
| gtid_executed_compression_period | 1000 |
| gtid_mode | ON |
| gtid_next | AUTOMATIC |
| gtid_owned | |
| gtid_purged | |
| session_track_gtids | OFF |
+----------------------------------+-----------+
#由于之前只权限了一个ip，此刻在mysql01主数据库上再授权一个ip
mysql> grant replication slave on *.* to 'slave'@'192.168.136.230' identified by 'slave';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
#测试连接
[root@mysql ~]# mysql -uslave -pslave -h192.168.136.239
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 17
Server version: 5.7.33-log MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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>
#mysql03从库上root用户连接进行相应配置
[root@mysql03 ~]# mysql -uroot -p1
mysql> change master to
-> master_host='192.168.136.239', #主库ip
-> master_user='slave', #主库授权的普通用户
-> master_password='slave',
-> master_port=3306, #主库端口
-> master_auto_position=1; #位置从1开始同步
#也可以查看帮助进行配置
mysql> help change master to;
CHANGE MASTER TO
MASTER_HOST='source2.example.com',
MASTER_USER='replication',
MASTER_PASSWORD='password',
MASTER_PORT=3306,
MASTER_LOG_FILE='source2-bin.001',
MASTER_LOG_POS=4,
MASTER_CONNECT_RETRY=10;
URL: https://dev.mysql.com/doc/refman/5.7/en/change-master-to.html
#开启
mysql> start slave;
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.136.239
Master_User: slave
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master_bin.000002
Read_Master_Log_Pos: 2172
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 2387
Relay_Master_Log_File: master_bin.000002
Slave_IO_Running: Yes
Slave_SQL_Running: Yes #显示俩个yes则运行成功！
#mysql03查看数据库，数据库内容也同步成功
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)

8.GTID（俩主一从）

1.最新环境

版本	ip	主机名	身份
centos8	192.168.136.239	master01	主库
centos8	192.168.136.219	master02	主库
centos8	192.168.136.230	slave	从库

2.所有服务器均关闭防火墙或者放行防火墙

[root@master01 ~]# systemctl stop firewalld
[root@master01 ~]# systemctl disable firewalld
[root@master02 ~]# systemctl stop firewalld
[root@master02 ~]# systemctl disable firewalld
[root@slave ~]# systemctl stop firewalld
[root@slave ~]# systemctl disable firewalld

3.授权连接

master01库授权普通用户

mysql> grant replication slave on *.* to 'user'@'192.168.136.%' identified by 'user';

slave进行连接

[root@slave ~]# mysql -uuser -p'user' -h192.168.136.239
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.33 MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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.

master02授权普通用户

mysql> grant replication slave on *.* to 'app'@'192.168.136.%' identified by 'app';
Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

slave进行连接

[root@slave ~]# mysql -uapp -papp -h192.168.136.219
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.33 MySQL Community Server (GPL)
Copyright (c) 2000, 2021, Oracle and/or its affiliates.
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>

4.分别进行配置文件修改

#master01主机：
[root@master01 ~]# cat /etc/my.cnf
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
skip-grant-tables
log-bin = master_bin
server-id = 10
gtid-mode = on
enforce-gtid-consistency = on
log-slave-updates = 1
binlog-format = row
skip-slave-start = 1
#master02主机
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
#replication config
log-bin = master_bin
server-id = 11
gtid-mode = on
enforce-gtid-consistency = on
log-slave-updates = 1
binlog-format = row
skip-slave-start = 1
#slave主机
[mysqld]
basedir = /usr/local/mysql
datadir = /opt/data
socket = /tmp/mysql.sock
port = 3306
user = mysql
pid-file = /opt/data/mysql.pid
skip-name-resolve
log-bin = slave_bin
server-id = 13
gtid-mode = on
enforce-gtid-consistency = on
log-slave-updates = 1
binlog-format = row
skip-slave-start = 1

5.分别重启

[root@master01 ~]# systemctl restart mysqld
[root@master02 ~]# systemctl restart mysqld
[root@slave ~]# systemctl restart mysqld

6.在进行GTID多主一从配置前，先引入一个概念

channel(频道)：每一个channel都是一个独立的slave服务，都有一个IO_THREAD和SQL_THREAD，原理和普通复制一样，只是需要在change master to语句后面使用FOR Channel来进行区分slave

在使用channel时需要将从库的master-info-repository、relay-log-info-repository设置为table，否则会报错。

将信息存储库设置为table格式

方式一（mysql内设置）:
set global master_info_repository='table';
set global relay_log_info_repository='table';
方式二（/etc/my.cnf内设置）:
3.在my.cnf中设置
master_info_repository = TABLE
relay_log_info_repository = TABLE
#检查是否更改成功
mysql> show variables where variable_name in ('relay_log_info_repository','master_info_repository');
+---------------------------+-------+
| Variable_name | Value |
+---------------------------+-------+
| master_info_repository | TABLE |
| relay_log_info_repository | TABLE |
+---------------------------+-------+

7.slave从库以root用户登录进行GTID配置

#slave从库上配置俩个主库GTID复制
mysql> change master to
-> master_host='192.168.136.219', #mysql02主库ip
-> master_user='app', #mysql02主库授权的普通用户
-> master_password='app', #mysql02主库授权的普通用户密码
-> master_port=3306, #主库端口
-> master_auto_position=1 for channel 'master01'; #位置从1开始同步,并且第一个slave取名master01
mysql> change master to
-> master_host='192.168.136.239', #mysql01主库ip
-> master_user='user',
-> master_password='user',
-> master_port=3306, #主库端口
-> master_auto_position=1 for channel 'master02'; #位置从1开始同步,并且第一个slave取名master01
#查看俩个slave状态
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.136.219
Master_User: app
Master_Port: 3306
Connect_Retry: 60
Master_Log_File:
Read_Master_Log_Pos: 4
Relay_Log_File: slave02-relay-bin-master1.000001
Relay_Log_Pos: 4
Relay_Master_Log_File:
Slave_IO_Running: No
Slave_SQL_Running: No #都是关闭的
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: 0
Relay_Log_Space: 154
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: NULL
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: 0
Master_UUID:
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
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: b4326a77-0a31-11ec-a991-000c298d3571:1-2,
d68b404d-0a35-11ec-9df1-000c29581959:1
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name: master1
Master_TLS_Version:
*************************** 2. row ***************************
Slave_IO_State:
Master_Host: 192.168.136.239
Master_User: user
Master_Port: 3306
Connect_Retry: 60
Master_Log_File:
Read_Master_Log_Pos: 4
Relay_Log_File: slave02-relay-bin-master2.000001
Relay_Log_Pos: 4
Relay_Master_Log_File:
Slave_IO_Running: No
Slave_SQL_Running: No
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: 0
Relay_Log_Space: 154
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: NULL
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: 0
Master_UUID:
Master_Info_File: mysql.slave_master_info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
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: b4326a77-0a31-11ec-a991-000c298d3571:1-2,
d68b404d-0a35-11ec-9df1-000c29581959:1
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name: master2
Master_TLS_Version:
2 rows in set (0.00 sec)
#开启俩个slave
mysql> start slave;
#再次查看状态

GTID(俩主一从)测试：

#master01主库创建一个test数据库
mysql> create database test;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)
#master02主库上查看
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys | #没有内容
+--------------------+
4 rows in set (0.00 sec)
#slave从库查看
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test | #已经同步了test库
+--------------------+
5 rows in set (0.00 sec)
#mysql02主库创建一个RHCA数据库
mysql> create database RHCA;
Query OK, 1 row affected (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| RHCA |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)
#slave从库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| RHCA |
| mysql |
| performance_schema |
| sys | #有了mysql01主库的test库和mysql02的RHCA的库
| test |
+--------------------+
6 rows in set (0.00 sec)

slave相关命令：

show slave status； //查看全部slave状态

show slave status for channel ‘naem'; //查看单个slave状态

reset slave; #重置全部slave

reset slave for channel ‘master1'; #重置单个slave

stop slave for channel ‘master1'; #暂停单个slave

start slave for channel ‘master1'; #开启单个slave

虽然我在做的过程没有遇到错误，但是下面这个是最最容易出现的错误

配置完开启slave出现报错