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[HowTo] Back Up and Restore MySQL Databases with Mysqldump

Posted: Thu Sep 13, 2018 5:39 pm
by xorro
This tutorial explains how to backup and restore MySQL or MariaDB databases from the command line using the mysqldump utility.

The backup files created by the mysqldump utility are basically a set of SQL statements that can be used to recreate the original database.

If you don’t backup your databases, a software bug or a hard-drive failure could be disastrous. To help save you lots of time and frustration, it is strongly recommended that you take the precaution of regularly backing up your MySQL databases.

You can also use the mysqldump utility to transfer your MySQL database to another MySQL server.
Mysqldump Command Syntax

Before going into how to use the mysqldump command, let’s start by reviewing the basic syntax.

The mysqldump utility expressions take the following form:

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mysqldump [options] > file.sql
  • file.sql - The dump (backup) file
Backup a Single MySQL Database

To create a backup of a database named database_name using the user root and save it to a file named database_name.sql you would run the following command:

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mysqldump -u root -p database_name > database_name.sql
You will be prompted to enter the root password. Enter it, press Enter and the dump process will start. Depending on the database size, the process can take some time.

If you are logged in as the same user that you are using to perform the export and that user does not require a password, you can omit the -u and -p options:

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mysqldump database_name > database_name.sql
Backup Multiple MySQL Databases

To backup multiple MySQL database with one command you need to use the --database option followed by the list of databases you want to backup. Each database name must be separated by space.

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mysqldump -u root -p --database database_name_a database_name_b > databases_a_b.sql
The command above will create a dump file containing both databases.

Backup All MySQL Databases

To back up all the MySQL databases you would use the --all-databases option:

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mysqldump -u root -p --all-databases > all_databases.sql
Same as with the previous example the command above will create a single dump file containing all databases.

Backup all MySQL databases to separate files

The mysqldump utility doesn’t provide an option to backup all databases to separate files but we easily achieve that with a simple bash FOR loop:

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for DB in $(mysql -e 'show databases' -s --skip-column-names); do
    mysqldump $DB > "$DB.sql";
The command above will create a separate dump file of all databases using the database name as the filename.

Create a Compressed MySQL Database Backup

If the database size is very large it is a good idea to compress the output. To do that simply pipe the output to the gzip utility, and redirect it to a file as shown bellow:

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mysqldump database_name > | gzip > database_name.sql.gz
Create a Backup with Timestamp

If you want to keep more than one backup in a same location, then you would like to add the date to the backup filename:

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mysqldump  database_name > database_name-$(date +%Y%m%d).sql
The command above will create a file with the following format database_name-20180617.sql

If you are using cronjob to automate your databases backups then you can also use the following command to delete any backups older than 30 days:

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find /path/to/backups -type f -name "*.sql" -mtime +30 -delete
Of course you need to adjust the command according to your backup location and file names. To learn more about the find command check our How to Find Files in Linux Using the Command Line guide.

Restoring a MySQL dump

You can restore a MySQL dump using the mysql tool. In most cases you’ll need to create a database to import into. If the database already exist first you need to delete it.

In the following example the first command will create a database named database_name and then it will import the dump database_name.sql into it:

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mysql -u root -p -e "create database database_name";
mysql -u root -p database_name < database_name.sql
Restore a Single MySQL Database from a Full MySQL Dump

If you backed up all your databases using the -all-databases option and you want to restore a single database from a backup file which contains multiple databases use the --one-database option as shown bellow:

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mysql --one-database database_name < all_databases.sql
Export and Import a MySQL Database in One Command

Instead of creating a dump file from one database and then import the backup into another MySQL database you can use the following one-liner:

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mysqldump -u root -p database_name | mysql -h remote_host -u root -p remote_database_name
The command above will pipe the output to a mysql client on remote host and it will import it into a database named remote_database_name. Before running the command, make sure the database already exists on the remote server.