Difference between revisions of "MySQL"
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[[Category:Database management systems]] | [[Category:Database management systems]] | ||
[[cs:MySQL]] | [[cs:MySQL]] | ||
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[[zh-CN:MySQL]] | [[zh-CN:MySQL]] | ||
MySQL is a widely spread, multi-threaded, multi-user SQL database. For more information about features, see the [http://www.mysql.com/ official homepage]. | MySQL is a widely spread, multi-threaded, multi-user SQL database. For more information about features, see the [http://www.mysql.com/ official homepage]. | ||
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− | + | {{Note|MariaDB is now officially our default implementation of MySQL.It is recommended for all users to upgrade to [[MariaDB]]. MySQL will be dropped from the repositories to the AUR before 2013/4/26. See [https://www.archlinux.org/news/mariadb-replaces-mysql-in-repositories/ the announcement].}} | |
− | # | + | |
+ | == Upgrade to MariaDB == | ||
+ | Users who want to switch will need to install mariadb, libmariadbclient or mariadb-clients and execute mysql_upgrade in order to migrate their systems. | ||
+ | # systemctl stop mysqld | ||
+ | # pacman -S mariadb libmariadbclient mariadb-clients | ||
+ | # systemctl start mysqld | ||
+ | # mysql_upgrade -p | ||
− | + | == Installation == | |
− | + | [[pacman|Install]] the {{Pkg|mysql}} package from the [[Official Repositories|official repositories]]. | |
− | + | After installing MySQL, start the ''mysqld'' [[Daemons|daemon]]. | |
− | + | Run the setup script and restart the daemon afterwards: | |
− | # systemctl | + | # mysql_secure_installation |
+ | # systemctl restart mysqld | ||
== Configuration == | == Configuration == | ||
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$ mysql -p -u root | $ mysql -p -u root | ||
− | === | + | === Disable remote access === |
− | The MySQL server | + | 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 {{ic|/etc/mysql/my.cnf}}: |
skip-networking | skip-networking | ||
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+ | You will still be able to log in from the localhost. | ||
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+ | === Enable auto-completion === | ||
+ | The MySQL client completion feature is disabled by default. To enable it system-wide edit {{ic|/etc/mysql/my.cnf}}, and replace {{ic|no-auto-rehash}} by {{ic|auto-rehash}}. Completion will be enabled next time you run the MySQL client. Please note that enabling this feature can make the client initialization longer. | ||
== Upgrading == | == Upgrading == | ||
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# mysql_upgrade -u root -p | # mysql_upgrade -u root -p | ||
− | == | + | == Backup == |
− | + | The database can be dumped to a file for easy backup. The following shell script will do this for you, creating a {{ic|db_backup.gz}} file in the same directory as the script, containing your database dump: | |
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− | + | {{bc|1= | |
− | + | #!/bin/bash | |
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− | + | THISDIR=`dirname $(readlink -f "$0")` | |
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− | + | mysqldump --single-transaction --flush-logs --master-data=2 --all-databases \ | |
− | + | <nowiki>|</nowiki> gzip > $THISDIR/db_backup.gz | |
− | + | echo 'purge master logs before date_sub(now(), interval 7 day);' <nowiki>|</nowiki> mysql | |
+ | }} | ||
− | + | See also the official [http://dev.mysql.com/doc/refman/5.6/en/mysqldump.html mysqldump page in the MySQL manual]. | |
== Troubleshooting == | == Troubleshooting == | ||
=== MySQL daemon cannot start === | === MySQL daemon cannot start === | ||
If you see something like this: | If you see something like this: | ||
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:: Starting MySQL [FAIL] | :: Starting MySQL [FAIL] | ||
and there is no entry in the log files, you might want to check the permissions of files in the directories {{ic|/var/lib/mysql}} and {{ic|/var/lib/mysql/mysql}}. If the owner of files in these directories is not {{ic|mysql:mysql}}, you should do the following: | and there is no entry in the log files, you might want to check the permissions of files in the directories {{ic|/var/lib/mysql}} and {{ic|/var/lib/mysql/mysql}}. If the owner of files in these directories is not {{ic|mysql:mysql}}, you should do the following: | ||
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If you run into permission problems despite having followed the above, ensure that your {{ic|my.cnf}} is copied to {{ic|/etc/}}: | If you run into permission problems despite having followed the above, ensure that your {{ic|my.cnf}} is copied to {{ic|/etc/}}: | ||
# cp /etc/mysql/my.cnf /etc/my.cnf | # cp /etc/mysql/my.cnf /etc/my.cnf | ||
− | Now try and | + | Now try and start the daemon. |
If you get these messages in your {{ic|/var/lib/mysql/hostname.err}} | If you get these messages in your {{ic|/var/lib/mysql/hostname.err}} | ||
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[ERROR] Do you already have another mysqld server running on socket: /var/run/mysqld/mysqld.sock ? | [ERROR] Do you already have another mysqld server running on socket: /var/run/mysqld/mysqld.sock ? | ||
[ERROR] Aborting | [ERROR] Aborting | ||
− | + | The permissions of {{ic|/var/run/mysqld}} could be the culprit. | |
# chown mysql:mysql /var/run/mysqld -R | # chown mysql:mysql /var/run/mysqld -R | ||
+ | |||
If you run mysqld and the following error appears: | If you run mysqld and the following error appears: | ||
Fatal error: Can’t open and lock privilege tables: Table ‘mysql.host’ doesn’t exist | Fatal error: Can’t open and lock privilege tables: Table ‘mysql.host’ doesn’t exist | ||
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# mysql_install_db --user=mysql --ldata=/var/lib/mysql/ | # mysql_install_db --user=mysql --ldata=/var/lib/mysql/ | ||
− | === Unable to run mysql_upgrade because MySQL cannot start | + | === Unable to run mysql_upgrade because MySQL cannot start === |
Try run MySQL in safemode: | Try run MySQL in safemode: | ||
# mysqld_safe --datadir=/var/lib/mysql/ | # mysqld_safe --datadir=/var/lib/mysql/ | ||
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# mysql_upgrade -u root -p | # mysql_upgrade -u root -p | ||
− | === | + | === Reset the root password === |
− | Stop the mysqld daemon | + | Stop the ''mysqld'' [[Daemons|daemon]]. |
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# mysqld_safe --skip-grant-tables & | # mysqld_safe --skip-grant-tables & | ||
Connect to the mysql server | Connect to the mysql server | ||
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mysql> FLUSH PRIVILEGES; | mysql> FLUSH PRIVILEGES; | ||
mysql> exit | mysql> exit | ||
− | + | Start the ''mysqld'' daemon. | |
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− | == | + | == See also == |
* [[LAMP]] - Arch wiki article covering the setup of a LAMP server (Linux Apache MySQL PHP) | * [[LAMP]] - Arch wiki article covering the setup of a LAMP server (Linux Apache MySQL PHP) | ||
* http://www.mysql.com/ | * http://www.mysql.com/ | ||
* Front-ends: {{AUR|mysql-gui-tools}} {{AUR|mysql-workbench}} | * Front-ends: {{AUR|mysql-gui-tools}} {{AUR|mysql-workbench}} |
Revision as of 05:38, 26 March 2013
zh-CN:MySQL MySQL is a widely spread, multi-threaded, multi-user SQL database. For more information about features, see the official homepage.
Contents
Upgrade to MariaDB
Users who want to switch will need to install mariadb, libmariadbclient or mariadb-clients and execute mysql_upgrade in order to migrate their systems.
# systemctl stop mysqld # pacman -S mariadb libmariadbclient mariadb-clients # systemctl start mysqld # mysql_upgrade -p
Installation
Install the mysql package from the official repositories.
After installing MySQL, start the mysqld daemon.
Run the setup script and restart the daemon afterwards:
# mysql_secure_installation # systemctl restart mysqld
Configuration
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
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 /etc/mysql/my.cnf
:
skip-networking
You will still be able to log in from the localhost.
Enable auto-completion
The MySQL client completion feature is disabled by default. To enable it system-wide edit /etc/mysql/my.cnf
, and replace no-auto-rehash
by auto-rehash
. Completion will be enabled next time you run the MySQL client. Please note that enabling this feature can make the client initialization longer.
Upgrading
You might consider running this command after you have upgraded MySQL and started it:
# mysql_upgrade -u root -p
Backup
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.
Troubleshooting
MySQL daemon cannot start
If you see something like this:
:: Starting MySQL [FAIL]
and there is no entry in the log files, you might want to check the permissions of files in the directories /var/lib/mysql
and /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 /etc/
:
# cp /etc/mysql/my.cnf /etc/my.cnf
Now try and start the daemon.
If you get these messages in your /var/lib/mysql/hostname.err
[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
Stop the mysqld daemon.
# mysqld_safe --skip-grant-tables &
Connect to the mysql server
# mysql -u root mysql
Change root password:
mysql> UPDATE mysql.user SET Password=PASSWORD('MyNewPass') WHERE User='root'; mysql> FLUSH PRIVILEGES; mysql> exit
Start the mysqld daemon.
See also
- LAMP - Arch wiki article covering the setup of a LAMP server (Linux Apache MySQL PHP)
- http://www.mysql.com/
- Front-ends: mysql-gui-toolsAUR mysql-workbenchAUR