《云计算》-MySql基础:数据备份与恢复

1 数据备份与恢复
1.1 问题

本案例要求熟悉MySQL的备份与恢复,完成以下任务操作:

逻辑备份工具 mysqldump
使用mysql 恢复数据库

1.2 步骤

实现此案例需要按照如下步骤进行。

步骤一:使用mysqldump进行逻辑备份

1)备份MySQL服务器上的所有库

将所有的库备份为mysql-all.sql文件:

[root@dbsvr1 ~]# mysqldump -u root -p --all-databases > /root/alldb.sql
Enter password:                                  //验证口令
[root@dbsvr1 mysql]# file /root/alldb.sql          //确认备份文件类型
/root/alldb.sql: UTF-8 Unicode English text, with very long lines

查看备份文件alldb.sql的部分内容:

[root@dbsvr1 ~]# grep -vE '^/|^-|^$' /root/alldb.sql | head -15
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `home` /*!40100 DEFAULT CHARACTER SET latin1 */;
USE `home`;
DROP TABLE IF EXISTS `biao01`;
CREATE TABLE `biao01` (
  `id` int(2) NOT NULL,
  `name` varchar(8) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
LOCK TABLES `biao01` WRITE;
UNLOCK TABLES;
DROP TABLE IF EXISTS `biao02`;
CREATE TABLE `biao02` (
  `id` int(4) NOT NULL,
  `name` varchar(8) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
.. ..

注意:若数据库都使用MyISAM存储引擎,可以采用冷备份的方式,直接复制对应的数据库目录即可;恢复时重新复制回来就行。

2)只备份指定的某一个库

将userdb库备份为userdb.sql文件:

[root@dbsvr1 ~]# mysqldump -u root -p userdb > userdb.sql
Enter password:                                  //验证口令

查看备份文件userdb.sql的部分内容:

[root@dbsvr1 ~]# grep -vE '^/|^-|^$' /root/userdb.sql
DROP TABLE IF EXISTS `stu_info`;
CREATE TABLE `stu_info` (
  `name` varchar(12) NOT NULL,
  `gender` enum('boy','girl') DEFAULT 'boy',
  `age` int(3) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
LOCK TABLES `stu_info` WRITE;
.. ..

3)同时备份指定的多个库

同时备份mysql、userdb库,保存为mysql+userdb.sql文件:

[root@dbsvr1 ~]# mysqldump -u root -p -B mysql  userdb > mysql+test+userdb.sql
Enter password:                                  //验证口令

查看备份文件userdb.sql的部分内容:

[root@dbsvr1 ~]# grep '^CREATE DATA' /root/mysql+userdb.sql
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `mysql` /*!40100 DEFAULT CHARACTER SET latin1 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/ `userdb` /*!40100 DEFAULT CHARACTER SET latin1 */;

步骤二:使用mysql命令从备份中恢复数据库、表

以恢复userdb库为例,可参考下列操作。通常不建议直接覆盖旧库,而是采用建立新库并导入逻辑备份的方式执行恢复,待新库正常后即可废弃或删除旧库。

1)创建名为userdb2的新库

mysql> CREATE DATABASE userdb2;
Query OK, 1 row affected (0.00 sec)

2)导入备份文件,在新库中重建表及数据

[root@dbsvr1 ~]# mysql -u root -p userdb2 < /root/userdb.sql
Enter password:                                  //验证口令

3)确认新库正常,启用新库

mysql> USE userdb2;                              //切换到新库
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> SELECT sn,username,uid,gid,homedir          //查询数据,确认可用
    -> FROM userlist LIMIT 10;
+----+----------+-----+-----+-----------------+
| sn | username | uid | gid | homedir         |
+----+----------+-----+-----+-----------------+
|  1 | root     |   0 |   0 | /root           |
|  2 | bin      |   1 |   1 | /bin            |
|  3 | daemon   |   2 |   2 | /sbin           |
|  4 | adm      |   3 |   4 | /var/adm        |
|  5 | lp       |   4 |   7 | /var/spool/lpd  |
|  6 | sync     |   5 |   0 | /sbin           |
|  7 | shutdown |   6 |   0 | /sbin           |
|  8 | halt     |   7 |   0 | /sbin           |
|  9 | mail     |   8 |  12 | /var/spool/mail |
| 10 | operator |  11 |   0 | /root           |
+----+----------+-----+-----+-----------------+
10 rows in set (0.00 sec)

4)废弃或删除旧库

mysql> DROP DATABASE userdb;
Query OK, 2 rows affected (0.09 sec)

2 使用binlog日志
2.1 问题

利用binlog恢复库表,要求如下:

启用binlog日志
创建db1库tb1表,插入3条记录
删除tb1表中刚插入的3条记录
使用mysqlbinlog恢复删除的3条记录

2.2 步骤

实现此案例需要按照如下步骤进行。

步骤一:启用binlog日志

1)调整/etc/my.cnf配置,并重启服务

[root@dbsvr1 ~]# vim  /etc/my.cnf
[mysqld]
.. ..
log-bin-index=mysql-bin                              //启用二进制日志,并指定前缀
server_id=1
binlog_format=STATEMENT                               
//在Mysql5.7中,binlog日志格式默认为ROW,但它不记录sql语句上下文相关信息。需要将binlog日志格式修改为STATEMENT
.. ..
[root@dbsvr1 ~]# systemctl  restart mysqld.service

2)确认binlog日志文件

新启用binlog后,每次启动MySQl服务都会新生成一份日志文件:

[root@dbsvr1 ~]# ls /var/lib/mysql/mysql-bin.*
/var/lib/mysql/mysql-bin.000001  /var/lib/mysql/mysql-bin.index

其中mysql-bin.index文件记录了当前保持的二进制文件列表:

[root@dbsvr1 ~]# cat /var/lib/mysql/mysql-bin.index
./mysql-bin.000001

重启MySQL服务程序,或者执行SQL操作“FLUSH LOGS;”,会生成一份新的日志:

[root@dbsvr1 ~]# ls /var/lib/mysql/mysql-bin.*
/var/lib/mysql/mysql-bin.000001  /var/lib/mysql/mysql-bin.index
/var/lib/mysql/mysql-bin.000002
[root@dbsvr1 ~]# cat /var/lib/mysql/mysql-bin.index
./mysql-bin.000001
./mysql-bin.000002

步骤二:利用binlog日志重做数据库操作

1)执行数据库表添加操作

创建db1·库tb1表,表结构自定义:

mysql> CREATE DATABASE db1;
Query OK, 1 row affected (0.05 sec)
mysql> USE db1;
Database changed
mysql> CREATE TABLE tb1(
    -> id int(4) NOT NULL,name varchar(24)
    -> );
Query OK, 0 rows affected (0.28 sec)

插入3条表记录:

mysql> INSERT INTO tb1 VALUES
    -> (1,'Jack'),
    -> (2,'Kenthy'),
    -> (3,'Bob');
Query OK, 3 rows affected (0.12 sec)
Records: 3  Duplicates: 0  Warnings: 0

确认插入的表记录数据:

mysql> SELECT * FROM tb1;
+----+--------+
| id | name   |
+----+--------+
|  1 | Jack   |
|  2 | Kenthy |
|  3 | Bob    |
+----+--------+
3 rows in set (0.00 sec)

2)删除前一步添加的3条表记录

执行删除所有表记录操作:

mysql> DELETE FROM tb1;
Query OK, 3 rows affected (0.09  sec)

确认删除结果:

mysql> SELECT * FROM tb1;
Empty set (0.00 sec)

步骤三:通过binlog日志恢复表记录

binlog会记录所有的数据库、表更改操作,所以可在必要的时候重新执行以前做过的一部分数据操作,但对于启用binlog之前已经存在的库、表数据将不适用。

根据上述“恢复被删除的3条表记录”的需求,应通过mysqlbinlog工具查看相关日志文件,找到删除这些表记录的时间点,只要恢复此前的SQL操作(主要是插入那3条记录的操作)即可。

1)查看mysql-bin.000002日志内容

[root@dbsvr1 ~]# mysqlbinlog /var/lib/mysql/mysql-bin.000002
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#170412 12:05:32 server id 1  end_log_pos 123 CRC32 0x6d8c069c  Start: binlog v 4, server v 5.7.17-log created 170412 12:05:32 at startup
# Warning: this binlog is either in use or was not closed properly.
ROLLBACK/*!*/;
BINLOG '
jKftWA8BAAAAdwAAAHsAAAABAAQANS43LjE3LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAACMp+1YEzgNAAgAEgAEBAQEEgAAXwAEGggAAAAICAgCAAAACgoKKioAEjQA
AZwGjG0=
'/*!*/;
# at 123
#170412 12:05:32 server id 1  end_log_pos 154 CRC32 0x17f50164  Previous-GTIDs
# [empty]
# at 154
#170412 12:05:59 server id 1  end_log_pos 219 CRC32 0x4ba5a976  Anonymous_GTID  last_committed=0        sequence_number=1
SET @@SESSION.GTID_NEXT= 'ANONYMOUS'/*!*/;
# at 219
#170412 12:05:59 server id 1  end_log_pos 310 CRC32 0x5b66ae13  Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=1491969959/*!*/;
SET @@session.pseudo_thread_id=3/*!*/;
SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;
SET @@session.sql_mode=1436549152/*!*/;
SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
/*!\C utf8 *//*!*/;
SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=8/*!*/;
SET @@session.lc_time_names=0/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
CREATE DATABASE db1
/*!*/;
# at 310
#170412 12:06:23 server id 1  end_log_pos 375 CRC32 0x2967cc28  Anonymous_GTID  last_committed=1        sequence_number=2
SET @@SESSION.GTID_NEXT= 'ANONYMOUS'/*!*/;
# at 375
#170412 12:06:23 server id 1  end_log_pos 502 CRC32 0x5de09aae  Query   thread_id=3     exec_time=0     error_code=0
use `db1`/*!*/;
SET TIMESTAMP=1491969983/*!*/;
CREATE TABLE tb1(
id int(4) NOT NULL,name varchar(24)
)
/*!*/;
# at 502
#170412 12:06:55 server id 1  end_log_pos 567 CRC32 0x0b8cd418  Anonymous_GTID  last_committed=2        sequence_number=3
SET @@SESSION.GTID_NEXT= 'ANONYMOUS'/*!*/;
# at 567
#170412 12:06:55 server id 1  end_log_pos 644 CRC32 0x7e8f2fa0  Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=1491970015/*!*/;
BEGIN
/*!*/;
# at 644
#170412 12:06:55 server id 1  end_log_pos 772 CRC32 0x4e3f728e  Query   thread_id=3     exec_time=0     error_code=0                            //插入表记录的起始时间点 
SET TIMESTAMP=1491970015/*!*/;
INSERT INTO tb1 VALUES(1,'Jack'),(2,'Kenthy'), (3,'Bob')
/*!*/;
# at 772
#170412 12:06:55 server id 1  end_log_pos 803 CRC32 0x6138b21f  Xid = 10
                                                      //确认事务的时间点 
COMMIT/*!*/;
# at 803
#170412 12:07:24 server id 1  end_log_pos 868 CRC32 0xbef3f472  Anonymous_GTID  last_committed=3        sequence_number=4
SET @@SESSION.GTID_NEXT= 'ANONYMOUS'/*!*/;
# at 868
#170412 12:07:24 server id 1  end_log_pos 945 CRC32 0x5684e92c  Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=1491970044/*!*/;
BEGIN
/*!*/;
# at 945
#170412 12:07:24 server id 1  end_log_pos 1032 CRC32 0x4c1c75fc         Query   thread_id=3     exec_time=0     error_code=0            //删除表记录的时间点
SET TIMESTAMP=1491970044/*!*/;
DELETE FROM tb1
/*!*/;
# at 1032
#170412 12:07:24 server id 1  end_log_pos 1063 CRC32 0xccf549b2         Xid = 12
COMMIT/*!*/;
SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/;
DELIMITER ;
# End of log file
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

2) 执行指定Pos节点范围内的sql命令恢复数据

根据上述日志分析,只要恢复从2014.01.12 20:12:14到2014.01.12 20:13:50之间的操作即可。可通过mysqlbinlog指定时间范围输出,结合管道交给msyql命令执行导入重做:

[root@dbsvr1 ~]# mysqlbinlog \
    --start-datetime="2017-04-12 12:06:55" \ 
    --stop-datetime="2017-04-12 12:07:23" \
    /var/lib/mysql/mysql-bin.000002 | mysql -u root -p
Enter password:                                     //验证口令

3)确认恢复结果

mysql> SELECT * FROM db1.tb1;
+----+--------+
| id | name   |
+----+--------+
|  1 | Jack   |
|  2 | Kenthy |
|  3 | Bob    |
+----+--------+
3 rows in set (0.00 sec)
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