Changes

To get started, [https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Managing_Confined_Services/chap-Managing_Confined_Services-MySQL.html installing MySQL on RHEL] is as simple as <source lang="bash">yum install mysql-server</source>. However, you might get a message that your system is not registered to Red Hat Subscription Management (RHN in the old days), and thus the packages are not visible. To remedy this, you would of course use <code>subscription-manager</code> to register the host with Red Hat Subscription Management.

</source>

<source lang="sql">

CREATE DATABASE mediawiki;

</source>

The following command issues a new password for the root user while at the same time dictating which authentication plugin <ref>https://mariadb.com/kb/en/library/authentication-plugin-pam/</ref> to use.

<source lang="sql">

Note: Since the introduction of [https://mariadb.com/kb/en/library/development-pluggable-authentication/ Pluggable Authentication] in MySQL 5.7 and also MariaDB since 5.2, there is a "[https://mariadb.com/kb/en/library/authentication-plugin-unix-socket/ unix_socket]" plugin which authenticates the current user by their login to the OS, and thus NOT a password. If you have trouble setting the password, it's probably because you need to also specify the '''mysql_native_password''' auth at the same time <ref>https://www.percona.com/blog/2016/03/16/change-user-password-in-mysql-5-7-with-plugin-auth_socket/</ref>

Want to find out what's going on in your MySQL server, but don't want to install client tools and access? Just make sure that the General Query Log is turned on, and tail the log file:

<source lang="sql">

If you want more info than you can get from the direct query logging, then try [http://mtop.sourceforge.net/|mtop]

<code>SHOW GRANTS</code> only shows privs for the current user.

<source lang="sql">

</source>

https://mariadb.com/kb/en/library/differences-in-mariadb-in-debian-and-ubuntu/

</pre>

Then restart mysql/mariadb:

*<code>/bin/systemctl restart mariadb.service</code> for Fedora/Centos/RHEL

Reading output from the mysql command line client is notoriously ugly/hard. With the <code>-s --silent</code> or <code>-B --batch</code> options, you can get output that is more readable.

Aside from [[mysqldump]], there are also mysqlcheck, mysql_upgrade and other [https://dev.mysql.com/doc/refman/5.7/en/programs-client.html client programs].

Your data directory can fill up with binary logs unless you rotate them.

Either pass the name of a particular file, or a timestamp and MySQL will clear out the binary logs up to the one just specified (or the date)

<source lang="mysql">

-- consolidate the logs up to midnight 3 days ago

If you want to know which log files are in use so that you can remove superfluous ones without interrupting replication, go to your slave database and issue <tt>SHOW SLAVE STATUS\G

</tt>

When replication has little or no lag these are usually the same value. If there is a lot of replication lag, they will be different values. Choose the value for <tt>Relay_Master_Log_File</tt> just to be safe. Go back to the DB master and issue <tt>PURGE BINARY LOGS TO mysql-bin.000337</tt> where mysql-bin.000337 is the value of <tt>Relay_Master_Log_File</tt>

To persist this setup so your data directory doesn't fill up again, issue

<source lang="mysql">

Since the binlongs are used to recover the database state after a crash, this assumes that you are making database backups every day. If you only backup once per week, you would want at least 7 days worth of binlogs.

[[Category:Database]]