MySQL on Linux: installation, setup, and troubleshooting

Preferred version: MySQL 5.7.

Installation (CentOS)

CentOS 7 dropped MySQL from default repos in favor of MariaDB (largely compatible). To install Oracle MySQL, add the official Yum repo from open_in_new dev.mysql.com/downloads/repo/yum/ .

The repo package installs MySQL 8.0 by default. Edit the repo file to enable 5.7 instead if needed.

The repo package installs:

/etc/pki/rpm-gpg/RPM-GPG-KEY-mysql
/etc/yum.repos.d/mysql-community-source.repo
/etc/yum.repos.d/mysql-community.repo

Download and install the repo (example for el7):

wget https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm
rpm -ivh mysql80-community-release-el7-3.noarch.rpm

Enable the 5.7 repo and disable 8.0 in /etc/yum.repos.d/mysql-community.repo, then:

yum install mysql-community-server

Or for MySQL 8.0 as shipped by the repo:

yum install mysql-server

Start and secure

On CentOS the service is usually enabled at boot. Start it:

systemctl start mysqld

Temporary root password from the log:

grep 'temporary password' /var/log/mysqld.log

Run the secure setup script:

mysql_secure_installation

Troubleshooting

Leftover data after downgrade (8.0 → 5.7)

If MySQL 5.7 fails to start after removing 8.0, old data files may remain. Removing /var/lib/mysql/ (after backup) can fix a clean reinstall.

caching_sha2_password plugin (MySQL 8)

Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib/mysql/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory

MySQL 8 uses a new default authentication plugin. Switch the user to the legacy plugin:

ALTER USER root@localhost IDENTIFIED WITH mysql_native_password BY 'password';
FLUSH PRIVILEGES;

MySQL Workbench and MySQL 8

When creating users, Workbench may fail with SQL syntax errors around MAX_QUERIES_PER_HOUR — it targets MySQL 5.x better. Prefer MySQL 5.7 for compatibility with older tooling.