MySQL Backup notes

Classification dimension of backup

• The state of the database at the time of backup
  • Hot Backup( Hot standby )： Direct backup during normal operation
  • Cold Backup( Cold standby )： Backup after complete stop
  • Warm Backup( Warm preparation )： The database is read-only
• Format of backup file
  • Logical backup ： Output text or SQL sentence
  • The physical backup ( Naked file )： Back up the underlying files of the database , As for the InnoDB Come on , It is commonly .idb Files and other metadata files
• Backup content
  • Full backup ： Back up full data
  • Incremental backup ： Backup data differences
  • Log backup ： Backup Binlog(Binlog Represents all data differences during this period , That is, the operation of data change )

Examples of tools

• mysqldump： Logic 、 heat 、 Full volume backup
• xtrabackup： Physics 、 heat 、 Total quantity + Incremental backup

Use OUTFILE Command backup

OUTFILE

• MySQL Native SQL Instructions
• The most original logical backup method
• The function and effect of backup depends on how to write SQL sentence

Usage mode

• First find out MySQL Export path of

  show variables like '%secure%';
  

• Use into outfile The command exports the query results to a file

  select * into outfile '/var/lib/mysql-files/out_file_test' from table_xxx;
  

matters needing attention

• stay InnoDB Under transaction , You can achieve a consistent view , That is, under the isolation level of repeatable reading , After opening the transaction , because MVCC The existence of , At this time, each table is at the same time
• Modify the separator ：fields terminated by
• Modify line breaks ：lines terminated by

defects

• The output text is relatively simple
• It is difficult to restore , Now it is often used to simply export data

OUTFILE How to improve ？

• Send automatically SELECT sentence , No need to send manually
• Automatically start a transaction
• Output INSERT sentence , It can be directly used to restore

mysqldump

• Very common MySQL Logical backup tool
• MySQL Server Bring their own
• The output backup content is sql sentence , Balance reading and reduction
• sql Statements take up less space

principle

• mysqldump Use the following statement to back up the data

  SELECT SQL_NO_CACHE FROM `table_xxx`;
  

• SQL_NO_CACHE The queried data will not enter SQL cache

Usage method

• Use the following statement to back up the data ：

  mysqldump -uroot -p111111 --databases d1 --single-transaction > xxx.sql;
  

• Directly execute the exported sql Files can be restored

  source xxx.sql;
  

matters needing attention

• –single-transaction： stay RR Level (InnoDB)
• –lock-all-tables： Use FTWRL Lock all tables (MyISAM)
• –lock-tables： Use READ LOCAL Lock the table of the current library (MyISAM)
• –all-databases： Back up all databases

shortcoming

• Export logical data , Slow backups
• Restore needs to be performed sql, The speed is also slow

Incremental backup

mysqldump Incremental backup is not allowed , Because it is sent to every table in the Library select * sentence , So how to realize incremental backup ？

Ideas ：

• binlog Faithfully recorded MySQL Data change
• mysqldump After full backup , It can be used binlog As an increment
• mysqldump Full backup , Switch to new binlog file
• When restoring from zero , Use full reduction +binlog Restore

step

One 、mysqldump Full volume backup

• mysqldump Use the following statement to back up the data in full ：

  mysqldump -uroot -p111111 --database d1 --single-transaction --flush-logs --master-data=2 > xxx.sql
  

• –flush-logs： Switch after backup binlog file

• –master-data=2： Record the binlog file name

Two 、binlog Incremental backup

• When incremental backup is required , Switch binlog file

  mysqladmin -uroot -p111111 flush-logs
  

• Add all new binlog File backup

3、 ... and 、 Restore

• First restore the old full backup

  source xxx.sql;
  

• And then binlog Incremental restore to database

  mysqlbinlog MySQL-bin.000002 ...( Multiple binlog The files are separated by spaces ) | mysql -u root -p 111111
  

XtraBackup The physical backup

Why physical backup is needed

• Direct backup InnoDB The underlying data file
• Export does not require conversion , Fast
• Less pressure on the database when working
• It is easier to realize incremental backup

Is it feasible to copy raw files directly ？

• Theoretically feasible , But there are many problems ：
• Backup at the same time frm file 、ibd file 、binlog file 、redo log Documents, etc.
• Restoring on different versions of databases and operating systems may have compatibility problems
• Must be cold backed up , Affect the business

Realize Physics + heat + Full volume backup

• Ideas ： utilize redo log, Backup ibd file + During backup redo log
• 1、 start-up redo log Listening to the thread , Start collecting redo log
• 2、 Copy ibd Data files
• 3、 Stop collecting redo log
• 4、 Add FTWRL Lock copy metadata frm

Realize Physics + heat + Incremental backup

• Ideas ： Same as the full volume level
• How to determine the increment ： According to each page LSN Number , Identify changing pages

Realize physical restore

• Ideas ：mysqld crash Crash recovery process is similar
• Restore ibd file , replay redo log

ibbackup

• Current name MySQL Enterprise Backup,InnoDB Official product
• Realize the above functions , Excellent performance

XtraBackup

• Percona The open source version developed by the company , Realization ibbackup All functions
• XtraBackup 8.0 -> MySQL 8.0
• XtraBackup 2.4 -> MySQL 5.1,5.5,5.6,5.7

XtraBackup Full use method

• Backup ：

  innobackupex --user=root --password=111111 backdir/    # backdir： Backup folder 
  

• Data restore ：( Stop mysqld)

  innobackupex --copy-back backdir/xxxx-xx-xx/
  

XtraBackup Incremental usage

• Incremental backup ：

  innobackupex --user=root --password=111111 --incremental backdir/ --incremental-basedir='/backdir/xxxx-xx-xx'
  

• Merge incremental backup into full backup

  innobackupex --apply-log backdir/xxxx-xx-xx/ --incremental-dir=backdir/yyyy-yy-yy/
  

How to nip in the bud

Authority isolation

• The account number assigned to the business application is only DML jurisdiction
• Development students use read-only accounts
• DBA Usually use a read-only account , Switch accounts during special operations

SQL Audit

• DBA In the development environment, the audit is about to go online SQL sentence
• Develop students to modify online database , Submit to DBA perform
• Inception Automatic audit tool

Pseudo delete table

• Rename the table before deleting it , Observe whether the business is affected
• Do not delete the table directly , Add a special suffix to the table name , Delete with script

Complete process

• Back up data before going online
• Prepare the production environment accident plan