恢复mysql数据库详细图解_binlog恢复mysql数据库超详细步骤
日常的數據備份及恢復測試,是DBA工作重中之重的事情,所以要做好備份及測試,日常的備份常見有mysqldump+binlog備份、xtrabackup+binlog備份,無論那一種,幾乎都少不了對binlog的備份,說明了binlog在數據恢復中的重要性,下面做個小測試,是工作中不少運維或者新人DBA容易犯的錯。
創建一個測試表tb1:
(root@localhost) [xuanzhi]> show create table tb1\G
*************************** 1. row ***************************
Table: tb1
Create Table: CREATE TABLE `tb1` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`name` char(10) CHARACTER SET latin1 DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
(root@localhost) [xuanzhi]>
往表里插入兩條數據:
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('aa'),('bb');
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
(root@localhost) [xuanzhi]> show master logs;
+----------------------+-----------+
| Log_name | File_size |
+----------------------+-----------+
| localhost-bin.000001 | 329 |
+----------------------+-----------+
1 row in set (0.00 sec)
(root@localhost) [xuanzhi]>
這個時候對數據備份,如果是xtrabackup備份的話,會在有xtrabackup_binlog_info文件中記錄此時備份是到那個binlog文件和pos點的,如果是mysqldump備份,則需要帶上--master-data=2這個參數,下面我們的數據量少,用mysqldump備份:
[root@localhost ~]# mysqldump -uroot -p123456 -R --events --triggers=true --master-data=2 --single-transaction xuanzhi > xuanzhi.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost ~]# grep -i "CHANGE MASTER" xuanzhi.sql
-- CHANGE MASTER TO MASTER_LOG_FILE='localhost-bin.000001', MASTER_LOG_POS=329;
[root@localhost ~]#
備份完后,繼續模擬數據庫有寫入,而還是寫在localhost-bin.000001
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('cc'),('dd');
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
(root@localhost) [xuanzhi]> show master logs;
+----------------------+-----------+
| Log_name | File_size |
+----------------------+-----------+
| localhost-bin.000001 | 538 |
+----------------------+-----------+
1 row in set (0.00 sec)
(root@localhost) [xuanzhi]> flush logs;
Query OK, 0 rows affected (0.01 sec)
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('ee');
Query OK, 1 row affected (0.00 sec)
(root@localhost) [xuanzhi]> show master logs;
+----------------------+-----------+
| Log_name | File_size |
+----------------------+-----------+
| localhost-bin.000001 | 589 |
| localhost-bin.000002 | 321 |
+----------------------+-----------+
2 rows in set (0.00 sec)
(root@localhost) [xuanzhi]>
上面我們進行flush logs是為了模擬現在已經有多個binlog文件了,恢復時進行多個binlog一起恢復。
進行誤操,把xunazhi庫drop了:
(root@localhost) [xuanzhi]> drop database xuanzhi;
Query OK, 1 row affected (0.02 sec)
(root@localhost) [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
(root@localhost) [(none)]>
創建數據xuanzhi,把備份導入:
(root@localhost) [(none)]> create database xuanzhi;
Query OK, 1 row affected (0.00 sec)
[root@localhost ~]# mysql -uroot -p123456 xuanzhi <.>
Warning: Using a password on the command line interface can be insecure.
[root@localhost ~]#
查看數據:
(root@localhost) [(none)]> use xuanzhi
Database changed
(root@localhost) [xuanzhi]> select * from tb1;
+----+------+
| id | name |
+----+------+
| 1 | aa |
| 2 | bb |
+----+------+
2 rows in set (0.00 sec)
(root@localhost) [xuanzhi]>
可以看到備份前的數據恢復了,我們現在要結合Binlog來恢復,但前提要找出誤操作前的pos點,也就是drop database xuanzhi前的pos點:
[root@localhost ~]# mysqlbinlog -v --base64-output=DECODE-ROWS localhost-bin.000002 |grep -C 10 -i "drop database"
### INSERT INTO `xuanzhi`.`tb1`
### SET
### @1=5
### @2='ee'
# at 290
#170327 21:10:55 server id 1313306 end_log_pos 321 CRC32 0x825a2f99 Xid = 78
COMMIT/*!*/;
# at 321
#170327 21:19:25 server id 1313306 end_log_pos 422 CRC32 0x8c139cac Query thread_id=2 exec_time=0 error_code=0
SET TIMESTAMP=1490620765/*!*/;
drop database xuanzhi
/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
[root@localhost ~]# mysql -uroot -p123456 xuanzhi <.>
Warning: Using a password on the command line interface can be insecure.
[root@localhost ~]#
從上面可以看到,誤操作前的pos點是321,那我們現在通過binlog來進行數據恢復:
[root@localhost mysql-5.6]# mysqlbinlog --start-position=329 --stop-position=321 localhost-bin.000001 localhost-bin.000002 |mysql -uroot -p123456 xuanzhi
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql-5.6]#
--start-position是備份后記錄下的pos點,?--stop-position是誤操前的pos點,如果批多個binlog文件,那么start-position是第一個binlog文件的pos點,stop-position是最后一個binlog的pos點,下面我們看下數據是否恢復回來了:
(root@localhost) [xuanzhi]> select * from tb1;
+----+------+
| id | name |
+----+------+
| 1 | aa |
| 2 | bb |
| 3 | cc |
| 4 | dd |
| 5 | ee |
+----+------+
5 rows in set (0.00 sec)
(root@localhost) [xuanzhi]>
這里要提的是進行恢復前,要把需要恢復的binlog備份好,或者移動拷貝一份到另一個目錄,因為進行數據導入時也會繼續寫binlog。假如你沒有誤操作的情況下,就是想測試一下數據的恢復,很多人的操作是導入備份,再從備份里記錄的binlog文件名和pos點進行binlog恢復,發現步驟都很完美,也沒報錯,恢復后就是只有備份時的數據,沒有備份后的數據,下面測試一下給大家看:
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('aa'),('bb');
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
(root@localhost) [xuanzhi]> select * from tb1;
+----+------+
| id | name |
+----+------+
| 1 | aa |
| 2 | bb |
+----+------+
2 rows in set (0.00 sec)
(root@localhost) [xuanzhi]> show master logs;
+----------------------+-----------+
| Log_name | File_size |
+----------------------+-----------+
| localhost-bin.000001 | 329 |
+----------------------+-----------+
1 row in set (0.00 sec)
(root@localhost) [xuanzhi]>
進行備份操作:
[root@localhost ~]# mysqldump -uroot -p123456 -R --events --triggers=true --master-data=2 --single-transaction xuanzhi > xuanzhi.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost ~]# grep -i "change master" xuanzhi.sql
-- CHANGE MASTER TO MASTER_LOG_FILE='localhost-bin.000001', MASTER_LOG_POS=329;
[root@localhost ~]#
繼續寫localhost-bin.000001后進行flush logs生成新的binlog再繼續寫數據,這里只是想模擬localhost-bin.000001寫滿了切localhost-bin.000002,結合多個binlog一起恢復
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('cc'),('dd');
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
(root@localhost) [xuanzhi]> flush logs;
Query OK, 0 rows affected (0.00 sec)
(root@localhost) [xuanzhi]> insert into tb1 (name) value ('dd');
Query OK, 1 row affected (0.01 sec)
(root@localhost) [xuanzhi]> show master logs;
+----------------------+-----------+
| Log_name | File_size |
+----------------------+-----------+
| localhost-bin.000001 | 589 |
| localhost-bin.000002 | 321 |
+----------------------+-----------+
2 rows in set (0.00 sec)
(root@localhost) [xuanzhi]>
下面進行恢復測試,正常來說先把備份導入:
[root@localhost ~]# mysql -uroot -p123456 xuanzhi <.>
Warning: Using a password on the command line interface can be insecure.
[root@localhost ~]#
查看數據,只有備份的那兩條記錄:
(root@localhost) [xuanzhi]> select * from tb1;
+----+------+
| id | name |
+----+------+
| 1 | aa |
| 2 | bb |
+----+------+
2 rows in set (0.00 sec)
(root@localhost) [xuanzhi]>
那現在通過localhost-bin.000001,localhost-bin.000002來恢復后面那3條數據,那么起始pos是那個呢,就是上面備份完后備份文件里的那個pos,我們進到binlog的存放路徑:
可以看到備份后的數據是沒有恢復回來的。為什么呢?因為導入備份的時候,又開始寫binlog了,而你恢復時用的binlog也就是現在導入備份時正在寫的binlog。大體過程是這樣的:
1、導入備份后,備份的所有操作都寫進最后一個binlog了,也就是上面的localhost-bin.000002
2、進行binlog恢復,從備份文件里的pos點開始,按理來說是可以恢復到最新數據的,但是上面導入了備份,導入時的所有操作都會記錄到localhost-bin.000002
3、備份導入時會有DROP TABLE和CREATE TABLE的動作寫進binlog里,所以最終得到的數據,還是備份時的數據。
總結:
一、在恢復全備數據之前必須將該binlog文件移出,否則恢復過程中,會繼續寫入語句到binlog,最終導致增量恢復數據部分變得比較混亂
二、做好數據文件及binlog的備份至關重要,但不是備份完就算了,要定期進行數據恢復測試或演練
三、恢復時建議對外停止更新,即禁止更新數據庫
總結
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