主库已经上了生产，现在要用mysqldump搭建一个备库，如何在线上处理
主要考虑如下三个参数
参数配置
master-data
# --master-data=2功能：
（1）在备份时，会自动记录，二进制日志文件名和位置号
0 默认值
1 以change master to命令形式，可以用作主从复制
2 以注释的形式记录，备份时刻的文件名+postion号
（2）自动锁表
（3）如果配合--single-transaction，只对非InnoDB表进行锁表备份，InnoDB表进行“热“”备，实际上是实现快照备份。
single-transaction
# --single-transaction
开启InnoDB表的一致性快照备份，可以不锁表。
保证数据备份一致性的参数
原理：在备份开启的时候，显式的开启RR隔离级别来进行备份，
RR隔离级别读取的是事务开启时的数据快照，
所以备份的时候是备份开启时间点的数据。
然后这种方式下，加锁的时间很少。可以在尽量不影响业务的情况下，保证数据的一致性。
测试
mysqldump -uroot -S /tmp/mysql.sock
--single-transaction --master-data=1 --set-gtid-purged=OFF --hex-blob
--triggers --routines --events -A > /tmp/1.sql
2022-04-24T07:23:06.435443Z 12 Query FLUSH /*!40101 LOCAL */ TABLES
2022-04-24T07:23:06.435502Z 12 Query FLUSH TABLES WITH READ LOCK
2022-04-24T07:23:06.435563Z 12 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2022-04-24T07:23:06.435626Z 12 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2022-04-24T07:23:06.435692Z 12 Query SHOW MASTER STATUS
2022-04-24T07:23:06.435787Z 12 Query UNLOCK TABLES
查看备份文件
[root@chen ~]# head -n 40 /tmp/1.sql
-- MySQL dump 10.13 Distrib 5.7.33, for linux-glibc2.12 (x86_64)
--
-- Host: localhost Database:
-- ------------------------------------------------------
-- Server version 5.7.33-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
--
-- Position to start replication or point-in-time recovery from
--
CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000008', MASTER_LOG_POS=194;
--
-- Current Database: `mysql`
--
可以看到change master 没有加注释,并且在备份中有flush table with read lock 操作获取到binlog位点后立即解锁
mysqldump
-uroot -S /tmp/mysql.sock --single-transaction --master-data=1
--set-gtid-purged=OFF --hex-blob --triggers --routines --events -A
> /tmp/1.sql
2022-04-24T07:30:49.562809Z 13 Query FLUSH /*!40101 LOCAL */ TABLES
2022-04-24T07:30:49.570847Z 13 Query FLUSH TABLES WITH READ LOCK
2022-04-24T07:30:49.570926Z 13 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2022-04-24T07:30:49.570976Z 13 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2022-04-24T07:30:49.571039Z 13 Query SHOW MASTER STATUS
2022-04-24T07:30:49.571129Z 13 Query UNLOCK TABLES
查看备份文件
[root@chen ~]# head -n 30 /tmp/2.sql
-- MySQL dump 10.13 Distrib 5.7.33, for linux-glibc2.12 (x86_64)
--
-- Host: localhost Database:
-- ------------------------------------------------------
-- Server version 5.7.33-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
--
-- Position to start replication or point-in-time recovery from
--
-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000008', MASTER_LOG_POS=194;
--
-- Current Database: `mysql`
--
可以看到change master 加了注释,并且在备份中有flush table with read lock 操作获取到binlog位点后立即解锁
mysqldump
-uroot -S /tmp/mysql.sock --single-transaction --master-data=0
--set-gtid-purged=ON --hex-blob --triggers --routines --events -A >
/tmp/4.sql
2022-04-24T08:28:05.952221Z 23 Connect root@localhost on using Socket
2022-04-24T08:28:05.952348Z 23 Query /*!40100 SET @@SQL_MODE='' */
2022-04-24T08:28:05.952438Z 23 Query /*!40103 SET TIME_ZONE='+00:00' */
2022-04-24T08:28:05.952573Z 23 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2022-04-24T08:28:05.952653Z 23 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2022-04-24T08:28:05.952774Z 23 Query SHOW VARIABLES LIKE 'gtid\_mode'
2022-04-24T08:28:05.954390Z 23 Query SELECT @@GLOBAL.GTID_EXECUTED
2022-04-24T08:28:05.954475Z 23 Query UNLOCK TABLES
查看备份文件
-- Server version 5.7.33-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
SET @MYSQLDUMP_TEMP_LOG_BIN = @@SESSION.SQL_LOG_BIN;
SET @@SESSION.SQL_LOG_BIN= 0;
--
-- GTID state at the beginning of the backup
--
SET @@GLOBAL.GTID_PURGED='2f49e28c-bacf-11ec-9945-5254000a56df:1-15090';
--
-- Current Database: `mysql`
--
可以看到master-data不记录change master
set-gtid-purged
mysqldump
-uroot -S /tmp/mysql.sock --single-transaction --master-data=2
--set-gtid-purged=ON --hex-blob --triggers --routines --events -A
> /tmp/3.sql
2022-04-24T07:53:03.096378Z 17 Query FLUSH /*!40101 LOCAL */ TABLES
2022-04-24T07:53:03.099390Z 17 Query FLUSH TABLES WITH READ LOCK
2022-04-24T07:53:03.099472Z 17 Query SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ
2022-04-24T07:53:03.099530Z 17 Query START TRANSACTION /*!40100 WITH CONSISTENT SNAPSHOT */
2022-04-24T07:53:03.099624Z 17 Query SHOW VARIABLES LIKE 'gtid\_mode'
2022-04-24T07:53:03.101047Z 17 Query SELECT @@GLOBAL.GTID_EXECUTED
2022-04-24T07:53:03.101161Z 17 Query SHOW MASTER STATUS
2022-04-24T07:53:03.101242Z 17 Query UNLOCK TABLES
备份文件
-- Host: localhost Database:
-- ------------------------------------------------------
-- Server version 5.7.33-log
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
/*!40103 SET @OLD_TIME_ZONE=@@TIME_ZONE */;
/*!40103 SET TIME_ZONE='+00:00' */;
/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
SET @MYSQLDUMP_TEMP_LOG_BIN = @@SESSION.SQL_LOG_BIN;
SET @@SESSION.SQL_LOG_BIN= 0;
--
-- GTID state at the beginning of the backup
--
SET @@GLOBAL.GTID_PURGED='2f49e28c-bacf-11ec-9945-5254000a56df:1-15090';
--
-- Position to start replication or point-in-time recovery from
--
-- CHANGE MASTER TO MASTER_LOG_FILE='mysql-bin.000008', MASTER_LOG_POS=194;
--
-- Current Database: `mysql`
可以看到set-gtid-purged=ON，在备份文件中，有了关闭sql_log_bin的操作，还有个purged的操作
如果是用备份做从库的话，需要将这个参数打开，默认是打开的，因为如果不关闭sql_log_bin会生成本地GTID，如果是要应用到主库的话，需要将该参数设置为--set-gtid-purged=OFF
基于GTID的主从应该如何搭建
（1）主备开启GTID并设置server_id
server_id=572533306
gtid-mode=on
enforce-gtid-consistency=on
binlog_format=ROW
（2）建复制用户
create user 'repl'@'%' identified by 'repl123@UIOP';
GRANT REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'repl'@'%';
（3）导出数据
前面测试已经证明，备份用作从库需要--set-gtid-purged=ON
并且需要--master-data=0来保证主库不被锁表
mysqldump -uroot -S /tmp/mysql.sock --single-transaction
--master-data=0 --set-gtid-purged=ON --hex-blob --triggers --routines
--events -A > /tmp/all.sql
（4）从库导入数据
source /tmp/all.sql
（5）从库执行reset master
防止gtid_executed表在导入数据的过程中被覆盖，最好重置gtid_purged变量
（6）提起gtid_purged变量，执行
head -n 40 /tmp/all.sql
--
SET @@GLOBAL.GTID_PURGED='2f49e28c-bacf-11ec-9945-5254000a56df:1-15090';
--
执行
SET @@GLOBAL.GTID_PURGED='2f49e28c-bacf-11ec-9945-5254000a56df:1-15090';
（7）使用MASTER_AUTO_POSITION建立同步
CHANGE MASTER TO
MASTER_HOST='1.1.1.1',
MASTER_USER='repl',
MASTER_PASSWORD='repl',
MASTER_PORT=3306,
MASTER_AUTO_POSITION=1;
（8）启动slave
start slave ;
