Technology sharing | how to recover the erroneously deleted table and the data in the table?

author ： Yang Xiaoyun

Aikesheng Database Engineer , be responsible for MySQL Routine maintenance and DMP Product support . Good at mysql Fault handling .

In this paper, the source ： Original contribution

* Produced by aikesheng open source community , Original content is not allowed to be used without authorization , For reprint, please contact the editor and indicate the source .

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scene ：

The customer deleted a table by mistake , therefore Want to recover the data of a table , Expect to restore the data before deletion .

Premise ：

The recovery method of deleting a table by mistake in the database , The method described below is for the database with backup every day and opening binlog The log .

explain ： The test library in this article is test database , The test table is test in student surface .

One 、 Turn on binlog journal , And back up the data

1. Check whether the database is open binlog journal

If it's not on , You need the following methods to start

（1） stay linux Under the system , modify /etc/my.cnf file

# Edit mode enters /etc/my.cnf
vi /etc/my.cnf
# i Start editing 
#  stay #log bin  Add the following 
server_id=2
log_bin = mysql-bin
binlog_format = ROW
expire_logs_days = 30
log_bin_basename= / Database instance installation directory /log/binlog/ Port number /mysql-bin       
log_bin_index=/ Database instance installation directory /log/binlog/ Port number /mysql-bin.index
# esc  Exit the editor ,shift+: preservation 

（2） restart mysql service

systemctl restart mysqld

It has been opened here binlog 了 , You can use the check command to check whether it is enabled

2. Check the data in the data table

3. The backup data

Backup command format ：

mysqldump [ Options ]  Database name  [ Table name ] >  Script name 
mysqldump [ Options ] -- Database name  [ Options   Table name ] >  Script name 
mysqldump [ Options ] --all-databases [ Options ] >  Script name 

（1） Back up all databases

mysqldump -h10.186.63.4 -P4149 -uu1 [email protected] -all-databases > /test1.sql

（2） Backup single library （ Multiple libraries are separated by spaces ）

mysqldump -h10.186.63.4 -P4149 -uu1 [email protected] database > test2.sql

（3） Backup list ( Multiple tables are spaced with spaces )

mysqldump -h10.186.63.4 -P4149 -uu1 [email protected] database table  > test3.sql

（4） Backup the specified database to exclude some tables

mysqldump -h10.186.63.4 -P4149 -uu1 [email protected] database --ignore-table=db.tb --ignore-table=db.tb2 > /test4.sql

4. Delete the database after inserting data

insert data , Generate binlog journal

mysql> insert into student values('201215130',' Zhang San ',' male ',21,'IS');
Query OK, 1 row affected (0.03 sec)
mysql>  insert into student values('201215131',' Li Si ',' Woman ',20,'MA');
Query OK, 1 row affected (0.02 sec)

Delete database

mysql> drop database test;
Query OK, 1 row affected (0.10 sec)

Remember not to do anything at this time ！！！

Two 、 Restore data

1. View the current binlog

mysql>  show master status\G;
************************ 1. row ***************************
File: mysql-bin.000021
Position: 68403303
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set: 130df5fa-01c1-11ed-916a-02000aba3f04:1-446151
1 row in set (0.00 sec)
ERROR:
No query specified
 notes ：mysql-bin.000021 Files will be used as one of the sources for recovering deleted data 

2. Copy binlog journal

Change the current binlog Copy logs to other directories , To avoid subsequent operations on binlog Logs have an impact

cp  /test/data/mysql/log/binlog/4149/mysql-bin.000021  /root

3. Will convert binlog Log for sql

The command format is ：mysqlbinlog -d database mysql-bin file > xx.sql
Such as ：

/data/mysql/base/5.7.25/bin/mysqlbinlog -d test mysql-bin.000021 > 0021bin.sql
[[email protected] 4149]# /data/mysql/base/5.7.25/bin/mysqlbinlog -d test mysql-bin.000022 > 0022.sql
WARNING: The option --database has been used. It may filter parts of transactions, but will include the GTIDs in any case. If you want to exclude or include transactions, you should use the options --exclude-gtids or --include-gtids, respectively, instead.

Edit the converted sql file

vi 0021bin.sql

The inside Misoperation command (DROP command ) Delete all

Start restoring data after saving

4. Restore backup files

/data/mysql/base/5.7.25/bin/mysql -h10.186.63.4 -P4149 -uu1 [email protected]  < test.sql 

Check whether the database backup file is restored

mysql> show databases;
mysql> use test;
mysql> show tables;
mysql>select * from table;

5. Restore the data deleted after the backup

Comment out binlog Transformed sql This line in the file

SET @@GLOBAL.GTID_PURGED=
/*SET @@GLOBAL.GTID_PURGED=XXXX*/;

Specify the database where the deleted table is located , Import data

/data/mysql/base/5.7.25/bin/mysql -h10.186.63.4 -P4149 -uu1 [email protected]  test  < 0021bin.sql

View the recovered data

mysql> select * from test.student;
+-----------+-----------+------+------+-------+
| Sno       | Sname     | Ssex | Sage | Sdept |
+-----------+-----------+------+------+-------+
| 201215121 |  Li Yong       |  male    |   20 | CS    |
| 201215122 |  Liu Chen       |  Woman    |   19 | CS    |
| 201215123 |  Wang min.       |  Woman    |   18 | MA    |
| 201215125 |  Zhang Li       |  male    |   19 | IS    |
| 201215126 |  Li Yiping     |  male    |   18 | IS    |
| 201215127 |  Zhang Qin       |  Woman    |   19 | CS    |
| 201215128 |  Wang Fang       |  Woman    |   20 | MA    |
| 201215129 |  Huang Linlin     |  male    |   21 | IS    |
| 201215130 |  Li Si       |  Woman    |   20 | MA    |
| 201215131 |  Zhang San       |  male    |   21 | IS    |
+-----------+-----------+------+------+-------+
10 rows in set (0.00 sec)