MySQL is a widely spread, multi-threaded, multi-user SQL database. For more information about features, see the official homepage.
- 1 Installation
- 2 Configuration
- 3 Backup
- 4 Troubleshooting
- 5 See also
- Oracle MySQL — An implementation by Oracle Corporation.
- https://www.mysql.com/ || AUR
- Percona Server — An implementation by Percona LLC.
mysqld.service, and then run the setup script:
Front-ends available areAUR and its successor AUR.
Enable at startup
To start the MySQL daemon at boot, enable the
Upgrade from Oracle MySQL to MariaDB
Users who want to switch will need to stop
mysqld.service, install , start
mysqld.service, and execute:
# mysql_upgrade -p
in order to migrate their systems.
You might consider running this command after you have upgraded MySQL and started it:
# mysql_upgrade -u root -p
Once you have started the MySQL server, you probably want to add a root account in order to maintain your MySQL users and databases. This can be done manually or automatically, as mentioned by the output of the above script. Either run the commands to set a password for the root account, or run the secure installation script.
You now should be able to do further configuration using your favorite interface. For example you can use MySQL's command line tool to log in as root into your MySQL server:
$ mysql -p -u root
Grant Remote Access
If you want to access your MySQL server from other LAN hosts, you have to commen (with #) the following lines in your
[mysqld] ... #skip-networking #bind-address = <some ip-address> ...
Then you grant any mysql user you like remote access from your local network (example for root): Connect to your database with root:
mysql -p -u root
Check current users with remote access privileged:
SELECT User, Host FROM mysql.user WHERE Host <> 'localhost';
Now grant remote access for your user (here root)::
GRANT ALL PRIVILEGES ON *.* TO 'root'@'192.168.1.%' IDENTIFIED BY 'my_optional_remote_password' WITH GRANT OPTION;
You can change the '%' wildcard to a specific host if you like. The password can be different from user's main password.
Disable remote access
The MySQL server is accessible from the network by default. If MySQL is only needed for the localhost, you can improve security by not listening on TCP port 3306. To refuse remote connections, uncomment the following line in
You will still be able to log in from the localhost.
The MySQL client completion feature is disabled by default. To enable it system-wide edit
/etc/mysql/my.cnf, and replace
auto-rehash. Completion will be enabled next time you run the MySQL client.
/etc/mysql/my.cnf file section under the
mysqld group, add:
[mysqld] init_connect = 'SET collation_connection = utf8_general_ci,NAMES utf8' collation_server = utf8_general_ci character_set_client = utf8 character_set_server = utf8
Using a TMPFS for tmpdir
The directory used by MySQL for storing temporary files is named tmpdir. For example, it is used to perform disk based large sorts, as well as for internal and explicit temporary tables.
Create the directory with appropriate permissions:
# mkdir -pv /var/lib/mysqltmp # chown mysql:mysql /var/lib/mysqltmp
Find the id and gid of the
mysql user and group:
$ id mysql uid=27(mysql) gid=27(mysql) groups=27(mysql)
Add to your
tmpfs /var/lib/mysqltmp tmpfs rw,gid=27,uid=27,size=100m,mode=0750,noatime 0 0
Add to your
/etc/mysql/my.cnf file under the
tmpdir = /var/lib/mysqltmp
Then reboot or ( shutdown mysql, mount the tmpdir, start mysql ).
Time zone tables
Although time zone tables are created during the installation, they are not automatically populated. They need to be populated if you are planning on using CONVERT_TZ() in SQL queries.
To populate the time zone tables with all the time zones:
$ mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root mysql
Optionally, you may populate the table with specific time zone files:
$ mysql_tzinfo_to_sql <timezone_file> <timezone_name> | mysql -u root mysql
The database can be dumped to a file for easy backup. The following shell script will do this for you, creating a
db_backup.gz file in the same directory as the script, containing your database dump:
#!/bin/bash THISDIR=$(dirname $(readlink -f "$0")) mysqldump --single-transaction --flush-logs --master-data=2 --all-databases \ | gzip > $THISDIR/db_backup.gz echo 'purge master logs before date_sub(now(), interval 7 day);' | mysql
See also the official
mysqldump page in the MySQL manual.
MySQL daemon cannot start
If MySQL fails to start and there is no entry in the log files, you might want to check the permissions of files in the directories
/var/lib/mysql/mysql. If the owner of files in these directories is not
mysql:mysql, you should do the following:
# chown mysql:mysql /var/lib/mysql -R
If you run into permission problems despite having followed the above, ensure that your
my.cnf is copied to
# cp /etc/mysql/my.cnf /etc/my.cnf
Now try and start the daemon.
If you get these messages in your
[ERROR] Can't start server : Bind on unix socket: Permission denied [ERROR] Do you already have another mysqld server running on socket: /var/run/mysqld/mysqld.sock ? [ERROR] Aborting
the permissions of
/var/run/mysqld could be the culprit.
# chown mysql:mysql /var/run/mysqld -R
If you run mysqld and the following error appears:
Fatal error: Can’t open and lock privilege tables: Table ‘mysql.host’ doesn’t exist
Run the following command from the
/usr directory to install the default tables:
# cd /usr # mysql_install_db --user=mysql --ldata=/var/lib/mysql/
Unable to run mysql_upgrade because MySQL cannot start
Try run MySQL in safemode:
# mysqld_safe --datadir=/var/lib/mysql/
And then run:
# mysql_upgrade -u root -p
Reset the root password
mysqld.service. Issue the following command:
# mysqld_safe --skip-grant-tables &
Connect to the mysql server. Issue the following command:
# mysql -u root mysql
Change root password:
mysq/> use mysql; mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root'; mysql> FLUSH PRIVILEGES; mysql> exit
Check and repair all tables
Check and auto repair all tables in all databases, see more:
# mysqlcheck -A --auto-repair -u root -p
Optimize all tables
Forcefully optimize all tables, automatically fixing table errors that may come up.
# mysqlcheck -A --auto-repair -f -o -u root -p
OS error 22 when running on ZFS
If you are using ZFS and get the following error:
InnoDB: Operating system error number 22 in a file operation.
You need to disable aio_writes by adding a line to the mysqld-section in /etc/mysql/my.cnf
[mysqld] ... innodb_use_native_aio = 0
Cannot login through CLI, but phpmyadmin works well
This may happen if you're using a long (>70-75) password. As for 5.5.36, for some reason, mysql CLI cannot handle that much characters in readline mode. So, if you're planning to use the recommended password input mode:
$ mysql -u <user> -p Password:
consider changing the password to smaller one.