Production DataBases : mysql

This material is proposed for merging ... It should be merged with mysql. (Discuss)

MariaDB is a community-developed fork of the MySQL relational database management system intended to remain free under the GNU GPL. It is notable for being led by the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle.

This page assumed that you have a general knowledge about MariaDB, so if you are new to MySQL first take a look at the MariaDB wiki page for information about how are packaged for alpine linux.

Installation

Alpine Linux has dummy counterparts packages for those that are not close to that change from mysql to mariadb naming packages, please check the MariaDB wiki page for more information.

Take in consideration that the user mysql was created during instalation of packages, in the initialization section two users will be created in database init: root and mysql, and in that point only if are in their respective system accounts, will be able to connect to the database service.

apk add mysql mysql-client

That will install the most used ones.. mariadb-cient and mariadb-server, rest of packages are brief described here for more information, here are listed in orden of relevance for production server

MySQL name package	Since Alpine:	Brief usage	Related package
mysql	v2	it's a dummy package to easy install of mariadb	mariadb
mysql-client	v2	it's a dummy package to easy install of commands tools	mariadb-client
mariadb	v2	server equivalent to mysql-server	mariadb-common
mariadb-client	v2	connection command line and tools	mariadb-common
mariadb-doc	v3.0	manpages are there!	man man-pages
mariadb-connector-odbc	edge	coding or making OS level connections, to any DB without libs install	.
mariadb-connector-c	v3.8	coding connection on C sources	mariadb-connector-c-dev
mariadb-backup	v3.8	to external backup devices, not widely used, in past was inside mariadb package	.
mariadb-server-utils	v3.8	server commands not widely used, in past was inside mariadb package	.
mariadb-dev	v3.1	Need for compilations depends on source code	.
mariadb-test	v3.3	testing suite from MariaDB tools	.
mariadb-mytop	v3.9	data performance monitoring	.
mariadb-plugin-rocksdb	v3.9	plain key-value event relational for data	.
mariadb-static	v3.8	static libs for static non depends linking in builds	.
mariadb-embedded	v3.9	the libmysqld identical interface as the C client	mariadb-embedded-dev
mariadb-embedded-dev	v3.9	use the normal mysql.h and link with libmysqld instead of libmysqlclient	mariadb-dev
mariadb-openrc	v3.8	separate scripts, in past was embebed on server package	.

Initialization

The alpine package of MySQL/MariaDB are like normal tarball of MySQL one, admins must be know what they want.. there's no automatic window-like here.

The datadir are located to /var/lib/mysql must be owned by the mysql user and group. You can modify this behavior but must edit the service file at /etc/init.d directory. Also, you need to set datadir=<YOUR_DATADIR> under section [mysqld] at the config file.

1. Initialize the main mysql database, and the data dir as standardized to /var/lib/mysql by the rc script
2. Then initialize the service, root account and socket connection are enabled without password at this point
3. Setup the root account by asignes a proper password, this are purely paranoid. due next step already do that!
4. Setup and init the installation by running the mysql_secure_installation
5. Setup permissions for manage others users and databases

mysql_install_db --user=mysql --datadir=/var/lib/mysql

rc-service mariadb start

mysqladmin -u root password toor

After that, all are initializated to proceed with configuration, now can be done using the mysql_secure_installation script at the next section:

Configuration

In order to finish setup into MariaDB now provide this script called mysql_secure_instalation that also are present as mariadb-secure-installation, too. This script provides minimal and security setup to the database, and here are the questions made explained:

1. Enter current password for root (enter for none): this are if you previously setup as we done in previous section a root password, just provide it and press enter, must be provided due we already set previously and from now, this sript will access to the engine and alter many setting on the database. Correct respond are OK, successfully used password, moving on...
2. Switch to unix_socket authentication [Y/n] Setting the root password or using the unix_socket ensures that only admins can log into engine database. Since mysql 5.6 and mariadb 10.2 a new auth mechanish are set, by socket authentiaction, when system user are same as mysql/mariadb user, in this case, no password are need. In production servers this are not the case and must be disabled, so answer NO, and response will be ... skipping.
3. Change the root password? [Y/n] this answer are here only if the first one are just enter, or if can provide a better passowrd if no unix socket are set. Just press "n" only if you provided a good password, otherwise just
4. Remove anonymous users? [Y/n] this permits remove the anonymous user created to log using socket authentication, only working on unix-like system. In any case, production system must remove it, so answer Y and proper respond must be ... Success!.
5. Disallow root login remotely? [Y/n] Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network. For sure answer Y and proper respond must be ... Success!.
6. Remove test database and access to it? [Y/n] By default, MariaDB comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed, so answer Y and proper respond must be ... Success!.
7. Reload privilege tables now? [Y/n] Reloading the privilege tables will ensure that all changes made so far will take effect immediately, so answer Y and proper respond must be ... Success!.

After reponse all the questions.. restart the service with rc-service mariadb restart

Configuration files

Due today were influenced by systemd standardization, the famous my.cnf are not more the main config file for the server engine. Now only few variables are defined there and all the settings are provided by independent files into the /etc/my.cnf.d/ directory, user own config files are under ~/.my.cnf config file of each home dir, and are read after global ones; so then we have:

Config file	Path and name	Versions of Alpine	Contents to configure
my.cnf	/etc/mysql/my.cnf	v2 to v3.8	All the directives, Global config file
mariadb-server.cnf	/etc/my.cnf.d/mariadb-server.cnf	since 3.9	First Global config file, main directives
.my.cnf	$HOME	all	user name only config directives

Production settings

These setting are only recommended for some server settings, there are the recommendation for high production settings:

Config setting	Default	Recommended	Explanation
main ram	2G	8G - 16G	MariaDB/MySQL can run with 512M or 1G of ram, high production must use minimun of 4G or more.
data dir disk type	any	SSD	MariaDB/MySQL must run with faster SSD if high request will be produced.
collation_server	utf8_unicode_ci	utf8mb4_unicode_ci	With 8mb4 some characters are able to use more than a single byte.
character_set_client	iso8859-1	utf8 or utf8mb4	Important due are standard, for left to right use 8mb4 flavor
max_connections	151	100	total_connections = total_processes * (total_threads + script_servers + 1)
max_heap_table_size	16M	32M	allocate more memory to memory tables, for memory storage engines
tmp_table_size	16M	32M	It allows the sub queries to remain more in memory, making them faster
join_buffer_size	32M	64M	It allows the join queries to remain more in memory rather in temp files
innodb_file_format	unset	Barracuda	will allow longer indexes for important most used tables
innodb_large_prefix	unset	1	Must set if Barracuda file format are choosen
innodb_buffer_pool_size	128M	456M	hold as much tables and indexes in system memory as is possible
innodb_read_io_threads	16	32	On high I/O systems, a value greater than 1 may allow the disk I/O to be more sequential
innodb_write_io_threads	16	32	Only if you have SSD storage for the data MySQL/MariaDB database and temp files
innodb_buffer_pool_instances	1	2 or 4	Only for older MySQL/MariaDB engines,
innodb_io_capacity	200	1200 - 2600	Only if you have SSD storage for the data MySQL/MariaDB database and temp files
innodb_io_capacity_max	200	2400 - 5200	Only if you have SSD storage for the data MySQL/MariaDB database and temp files

If you have SSD disks, use the recommended suggestion, otherwise, use minimum suggested. If you have physical hard drives, use 2000 * the number of active drives in the array. If using NVMe or PCIe Flash, much larger numbers as high as 200000 can be used, but those lasted storage devices will be a short life of course.

Newer system Alpine packages can set in independent files in any case those commands always works and where are not apply just will ignore the output:

• On older Alpine system must set config files for MAX ALLOWED PACKETS to minimun proper amount:

sed -i "s|.*max_allowed_packet\s*=.*|max_allowed_packet = 100M|g" /etc/mysql/my.cnf
sed -i "s|.*max_allowed_packet\s*=.*|max_allowed_packet = 100M|g" /etc/my.cnf.d/mariadb-server.cnf

• Only allow local connections on cases where there's only one server or no expected to connect from others:

sed -i "s|.*bind-address\s*=.*|bind-address=127.0.0.1|g" /etc/mysql/my.cnf
sed -i "s|.*bind-address\s*=.*|bind-address=127.0.0.1|g" /etc/my.cnf.d/mariadb-server.cnf

• If are not in domain controller, dont search for hostnames to improve performance responses (ideal for local only servers):

sed -i "s|.*skip-networking.*|skip-networking|g" /etc/mysql/my.cnf
sed -i "s|.*skip-networking.*|skip-networking|g" /etc/my.cnf.d/mariadb-server.cnf

• Set default charset to UTF8MB4, in newer versions (since Alpine v3.9), just added a new file to added thus customization, but older versions (below Alpine v3.8)of the package does not have a charset section, so you must added manually to the main configuration in each respective section:

cat > /etc/my.cnf.d/mariadb-server-default-charset.cnf << EOF
[client]
default-character-set = utf8mb4

[mysqld]
collation_server = utf8mb4_unicode_ci
character_set_server = utf8mb4

[mysql]
default-character-set = utf8mb4
EOF

Updating or comming from upgrading

Mayor Upgrades beetween Alpine linux version are so easy as change the repository version, but the MySQL/MariaDB engine need some extra steps when this are performed:

Upgrade databases on major releases Upon a major version release of mariadb (for example mariadb-10.1.10-1 to mariadb-10.1.18-1), it is wise to upgrade databases:

1. keep the old database (mysql sheme) structure of the engine daemon, currently this are not more the case, today this not make sense anymore
2. upgrade the MariaDB/MySQL packages, of course with must be done if the upgrade process to mayor alpine version does not!
3. run the mysql_upgrade -u root -p script, providing the password or root, (from the new package version) against the old still-running database (mysql sheme). This will produce some error messages; however, the upgrade will succeed.
4. Restart the service

If are unable to run mysql_upgrade because MySQL cannot start try run MySQL in safemode with mysqld_safe --datadir=/var/lib/mysql/ command and then run the mysql_upgrade -u root -p script.

Relevant important notes

File system notes about the databases managed

Btrfs Notes

If the database (in /var/lib/mysql) resides on a btrfs file system, you should consider disabling Copy-on-Write for the directory before creating any database (schemes), after initialization you can enabled again. But .. on every database creation (scheme creation), you must disabled again, to avoid corrupted data.

ZFS Bock sizes

ZFS, unlike most other file systems, has a variable record size, or what is commonly referred to as a block size. By default, the recordsize on ZFS is 128KiB, which means it will dynamically allocate blocks of any size from 512B to 128KiB depending on the size of file being written. Most RDBMSes work in 8KiB-sized blocks by default. Although the block size is tunable for MySQL/MariaDB use an 8KiB block size by default.

It is usually desirable to tune ZFS instead to accommodate the databases, using a command such as zfs set recordsize=8K /var/lib/mysql (or change /var/lib/mysql to the mount point where /var/lib/mysql resides) and in the interest of saving memory, it is best to simply disable ZFS's caching of the database's file data and let the database do its own job with zfs set primarycache=metadata /var/lib/mysql (or change /var/lib/mysql to the mount point where /var/lib/mysql resides).

But beware, these kinds of tuning parameters are only if RDBMSes are setup in dedicated partitions, if your root and of course database are all in one partition, dont do that. Separate ones.

Restore root password

rc-service mysql stop

kill  `cat /run/mysqld/mysqld.pid`

/usr/bin/mysqld --datadir=/var/lib/mysql --pid-file=/run/mysqld/mysqld.pid --skip-grant-tables --skip-networking &

mysql -e "ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass';FLUSH PRIVILEGES;ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPass';FLUSH PRIVILEGES;set password = password('MyNewPass');"

kill  `cat /run/mysqld/mysqld.pid`

rc-service mariadb restart

See Also

• MariaDB wiki page
• Production LAMP system: Lighttpd + PHP + MySQL
• Alpine newbie developer