一、什么不一致
1.1、不一致
首先使用下面脚本来构建Executed_Gtid_Set与xtrabackup_binlog_info不一致，到底指的是什么不一致
1、准备测试数据 # 切换日志 mydba@192.168.85.132,3306 [replcrash]> flush binary logs; Query OK, 0 rows affected (0.07 sec) # 查看当前位置 mydba@192.168.85.132,3306 [replcrash]> show master status; +------------------+----------+--------------+------------------+-----------------------------------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+------------------+-----------------------------------------------+ | mysql-bin.000191 | 194 | | | 8ab82362-9c37-11e7-a858-000c29c1025c:1-507450 | +------------------+----------+--------------+------------------+-----------------------------------------------+ 1 row in set (0.00 sec) # 清空数据 mydba@192.168.85.132,3306 [replcrash]> truncate table py_user; Query OK, 0 rows affected (0.01 sec) mydba@192.168.85.132,3306 [replcrash]> show create table py_user; +---------+---------------------------------------------------------+ | Table | Create Table | +---------+---------------------------------------------------------+ | py_user | CREATE TABLE `py_user` ( `uid` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(32) DEFAULT NULL, `add_time` datetime DEFAULT CURRENT_TIMESTAMP, `server_id` varchar(10) DEFAULT NULL, PRIMARY KEY (`uid`), KEY `name` (`name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 | +---------+---------------------------------------------------------+ 1 row in set (0.04 sec) # 写入数据 mydba@192.168.85.132,3306 [replcrash]> insert into py_user(name,server_id) select left(uuid(),30),@@server_id; Query OK, 1 row affected (0.02 sec) Records: 1 Duplicates: 0 Warnings: 0 # 写入数据 mydba@192.168.85.132,3306 [replcrash]> insert into py_user(name,server_id) select left(uuid(),30),@@server_id; Query OK, 1 row affected (0.00 sec) Records: 1 Duplicates: 0 Warnings: 0 # 删除数据 mydba@192.168.85.132,3306 [replcrash]> delete from py_user where uid=2; Query OK, 1 row affected (0.04 sec) # 查看数据 mydba@192.168.85.132,3306 [replcrash]> select * from py_user; +-----+--------------------------------+---------------------+-----------+ | uid | name | add_time | server_id | +-----+--------------------------------+---------------------+-----------+ | 1 | 64410b10-f504-11e7-a71e-000c29 | 2018-01-09 14:14:46 | 1323306 | +-----+--------------------------------+---------------------+-----------+ 1 row in set (0.00 sec) # 查看当前位置 mydba@192.168.85.132,3306 [replcrash]> show master status; +------------------+----------+--------------+------------------+-----------------------------------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+------------------+-----------------------------------------------+ | mysql-bin.000191 | 1329 | | | 8ab82362-9c37-11e7-a858-000c29c1025c:1-507454 | +------------------+----------+--------------+------------------+-----------------------------------------------+ 1 row in set (0.00 sec) # 查看mysql.gtid_executed mydba@192.168.85.132,3306 [replcrash]> select * from mysql.gtid_executed; +--------------------------------------+----------------+--------------+ | source_uuid | interval_start | interval_end | +--------------------------------------+----------------+--------------+ | 8ab82362-9c37-11e7-a858-000c29c1025c | 1 | 507450 | +--------------------------------------+----------------+--------------+ 1 row in set (0.00 sec) 2、备份并还原到新实例 # backup [root@ZST1 ~]# innobackupex --defaults-file=/data/mysql/mysql3306/my.cnf -S /tmp/mysql3306.sock -uroot -pmysql5719 --no-timestamp /data/backup/full/20180109 # 查看备份位置 [root@ZST1 ~]# cat /data/backup/full/20180109/xtrabackup_binlog_info mysql-bin.000191 1329 8ab82362-9c37-11e7-a858-000c29c1025c:1-507454 [root@ZST1 ~]# # apply-log [root@ZST1 ~]# innobackupex --apply-log /data/backup/full/20180109 # 查看innodb位置(apply-log后生成) [root@ZST1 ~]# cat /data/backup/full/20180109/xtrabackup_binlog_pos_innodb mysql-bin.000191 1329 [root@ZST1 ~]# # copy-back • 需要恢复的MySQL实例需要关闭(关闭前reset master方便后续对比) • 目标datadir为空 • 手工把apply后的文件copy过去，或者 [root@ZST1 ~]# innobackupex --defaults-file=/data/mysql/mysql3308/my.cnf --copy-back /data/backup/full/20180109 • 更改copy过去的权限 [root@ZST1 ~]# chown -R mysql:mysql /data/mysql/mysql3308/data • 启动MySQL [root@ZST1 ~]# /usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/mysql3308/my.cnf & # 登录查询 mydba@192.168.85.132,3308 [replcrash]> show master status; +------------------+----------+--------------+------------------+-----------------------------------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+------------------+-----------------------------------------------+ | mysql-bin.000002 | 154 | | | 8ab82362-9c37-11e7-a858-000c29c1025c:1-507450 | +------------------+----------+--------------+------------------+-----------------------------------------------+ 1 row in set (0.00 sec) mydba@192.168.85.132,3308 [replcrash]> select * from mysql.gtid_executed; +--------------------------------------+----------------+--------------+ | source_uuid | interval_start | interval_end | +--------------------------------------+----------------+--------------+ | 8ab82362-9c37-11e7-a858-000c29c1025c | 1 | 507450 | +--------------------------------------+----------------+--------------+ 1 row in set (0.00 sec)
还原后通过show master status得到的Executed_Gtid_Set为8ab82362-9c37-11e7-a858-000c29c1025c:1-507450；实际备份的位置是8ab82362-9c37-11e7-a858-000c29c1025c:1-507454(xtrabackup_binlog_info)
上面就是Executed_Gtid_Set与xtrabackup_binlog_info不一致的例子，应该说大部分情况这两个值是不一致的。只是大部分的操作中，我们对Executed_Gtid_Set值基本无感，因此很少会注意到它们不一致
1.2、一致
下面我们执行flush binary logs，然后备份并进行后续操作
3、flush binary logs # 续上，3306执行flush logs操作 mydba@192.168.85.132,3306 [replcrash]> flush binary logs; Query OK, 0 rows affected (0.13 sec) # 查看mysql.gtid_executed mydba@192.168.85.132,3306 [replcrash]> select * from mysql.gtid_executed; +--------------------------------------+----------------+--------------+ | source_uuid | interval_start | interval_end | +--------------------------------------+----------------+--------------+ | 8ab82362-9c37-11e7-a858-000c29c1025c | 1 | 507454 | +--------------------------------------+----------------+--------------+ 1 row in set (0.00 sec) mysql.gtid_executed表中的信息已经更新 4、再一次备份并还原到新实例 # backup [root@ZST1 ~]# innobackupex --defaults-file=/data/mysql/mysql3306/my.cnf -S /tmp/mysql3306.sock -uroot -pmysql5719 --no-timestamp /data/backup/full/20180109new # 查看备份位置 [root@ZST1 ~]# cat /data/backup/full/20180109new/xtrabackup_binlog_info mysql-bin.000192 194 8ab82362-9c37-11e7-a858-000c29c1025c:1-507454 [root@ZST1 ~]# # apply-log [root@ZST1 ~]# innobackupex --apply-log /data/backup/full/20180109new # 查看innodb位置(apply-log后生成) [root@ZST1 ~]# cat /data/backup/full/20180109new/xtrabackup_binlog_pos_innodb mysql-bin.000191 1329 [root@ZST1 ~]# 注意此时xtrabackup_binlog_info与xtrabackup_binlog_pos_innodb也不一致。一般执行flush logs，或者ddl语句(<=5.7不记录redo)会导致两者不一致 # copy-back • 需要恢复的MySQL实例需要关闭(关闭前reset master方便后续对比) • 目标datadir为空 • 手工把apply后的文件copy过去，或者 [root@ZST1 ~]# innobackupex --defaults-file=/data/mysql/mysql3308/my.cnf --copy-back /data/backup/full/20180109new • 更改copy过去的权限 [root@ZST1 ~]# chown -R mysql:mysql /data/mysql/mysql3308/data • 启动MySQL [root@ZST1 ~]# /usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/mysql3308/my.cnf & # 登录查询 mydba@192.168.85.132,3308 [replcrash]> show master status; +------------------+----------+--------------+------------------+-----------------------------------------------+ | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set | +------------------+----------+--------------+------------------+-----------------------------------------------+ | mysql-bin.000002 | 154 | | | 8ab82362-9c37-11e7-a858-000c29c1025c:1-507454 | +------------------+----------+--------------+------------------+-----------------------------------------------+ 1 row in set (0.00 sec) mydba@192.168.85.132,3308 [replcrash]> select * from mysql.gtid_executed; +--------------------------------------+----------------+--------------+ | source_uuid | interval_start | interval_end | +--------------------------------------+----------------+--------------+ | 8ab82362-9c37-11e7-a858-000c29c1025c | 1 | 507454 | +--------------------------------------+----------------+--------------+ 1 row in set (0.00 sec)
还原后通过show master status得到的Executed_Gtid_Set为8ab82362-9c37-11e7-a858-000c29c1025c:1-507454；实际备份的位置是8ab82362-9c37-11e7-a858-000c29c1025c:1-507454(xtrabackup_binlog_info)
发现没有，flush binary logs后得到的备份，在还原后Executed_Gtid_Set与xtrabackup_binlog_info保持一致
二、为什么不一致
2.1、show master status
数据库实例刚启动时，MySQL 5.7从mysql.gtid_executed表获取执行过的事务的GTID->Executed_Gtid_Set
数据库实例运行过程中，show master status返回实时信息。开启binlog，mysql.gtid_executed需发生切换才写入新数据，那么show master status的数据是从哪获取的？
2.2、mysql.gtid_executed
还原后，我们看到的Executed_Gtid_Set信息应该来自mysql.gtid_executed(这里指的是还原后，还没有ddl、dml等操作)
mysql.gtid_executed表按照下面的方式写入
• 如果开启了binlog，在binlog切换时(flush binary logs/达到max_binlog_size/重启)，将当前的GTID插入到mysql.gtid_executed表中
• 如果没有开启binlog，每个事务提交前，会执行一个insert操作
原实例本身开启了binlog，当我们执行flush binary logs时就将当前的GTID信息写入到mysql.gtid_executed表。。。
第一次的测试，虽然有很多insert、delete，但是由于没有发生binlog切换，相应的GTID信息没有写入到mysql.gtid_executed表(innodb)，此时innobackupex备份，将对应的.ibd备份起来，还原后还是原来的数据
最开始并没注意到mysql.gtid_executed，总以为innobackupex会自己执行某个set gtid_purged语句。在配置文件开启general_log，并且starce 启动服务，结果毛线都没看到~~~
# general_log [mysqld] general_log=1 general_log_file=/data/mysql/mysql3308/data/mysql-general.log # strace shell> strace /usr/local/mysql/bin/mysqld --defaults-file=/data/mysql/mysql3308/my.cnf >/tmp/3308.log 2>&1
2.3、不一致会有什么影响
使用innobackupex的备份搭建从库，在还原后都需要通过xtrabackup_binlog_info或者xtrabackup_binlog_pos_innodb中的信息，SET @@GLOBAL.GTID_PURGED=‘uuid:seq‘;然后再做change master to操作
其他几个备份工具得到的GTID信息
# mysqldump [root@ZST1 ~]# mysqldump -h127.0.0.1 -P3306 -uroot -p --single-transaction --master-data=2 replcrash >/data/backup/replcrash_dump_1323306_`date +%Y%m%d`.sql [root@ZST1 ~]# more /data/backup/replcrash_dump_1323306_`date +%Y%m%d`.sql SET @@GLOBAL.GTID_PURGED=‘8ab82362-9c37-11e7-a858-000c29c1025c:1-507455‘; # mysqlpump [root@ZST1 ~]# mysqlpump -h127.0.0.1 -P3306 -uroot -p --single-transaction --add-drop-table --exclude-databases=mysql,sakila,backupdb -A >/data/backup/replcrash_pump_1323306_`date +%Y%m%d`.sql [root@ZST1 ~]# more /data/backup/replcrash_pump_1323306_`date +%Y%m%d`.sql SET @@GLOBAL.GTID_PURGED=/*!80000 ‘+‘*/ ‘8ab82362-9c37-11e7-a858-000c29c1025c:1-507455‘; # mydumper [root@ZST1 ~]# mydumper -h 127.0.0.1 -P 3306 -u root -p mysql5719 -v 3 -B replcrash -o /data/backup/mydumper [root@ZST1 ~]# more /data/backup/mydumper/metadata Started dump at: 2018-01-09 16:59:37 SHOW MASTER STATUS: Log: mysql-bin.000192 Pos: 353 GTID:8ab82362-9c37-11e7-a858-000c29c1025c:1-507455 Finished dump at: 2018-01-09 16:59:38 # innobackupex [root@ZST1 ~]# innobackupex --defaults-file=/data/mysql/mysql3306/my.cnf -S /tmp/mysql3306.sock -uroot -pmysql5719 --no-timestamp /data/backup/full/20180109 [root@ZST1 ~]# more /data/backup/full/20180109/xtrabackup_binlog_info mysql-bin.000191 1329 8ab82362-9c37-11e7-a858-000c29c1025c:1-507454 [root@ZST1 ~]# innobackupex之后，在原实例执行过truncate table py_user，因此上面的gtid不一样
使用mydumper(myloader不会产生binlog，也不会应用metadata中的GTID)和innobackupex的备份文件搭建从库，需要手动SET @@GLOBAL.GTID_PURGED
我们创建了不少的数据库备份，但却很少去检验备份是否有效。即使偶尔使用备份搭建测试环境、搭建从库、恢复数据
• 搭建测试环境，还原~game over
• 恢复数据，全备+binlog完美~game over
• 搭建从库，还原+reset master+change master to~game over
我们脑子里都有相应的套路，只需按步骤PaPaPa，就能完成大部分工作。经验之谈让我们规避了不少坑，同时也"错过"深挖坑的机会~
