MySQL or MariaDB database service consumes a lot of CPU on a Linux Plesk server

Symptoms

• The mysqld or mariadbdservice on a Linux Plesk server consumes a great percentage of the overall of CPU resources on the server

Cause

The MySQL or MariaDB database server is not tuned or optimized, due to which it uses too much of the server's available CPU resources.

Resolution

Note: Database performance tuning is out of the scope of Plesk Free Technical Support. This serves as a general-purpose guide.

Optimize the MySQL or MariaDB database by following these steps:

1. Log into Plesk

2. Go to Tools & Settings > Performance Booster > Serverwide

3. Once MySQL or MariaDB appears (this may take around a minute), press show values to be optimized

4. Press Apply

Applying the changes will restart the database server.

At that point you should monitor CPU usage for MySQL and MariaDB closely and if CPU consumption increases too much again, consider reviewing the SQL code of a database that has slow queries. 

General additional explanations on how this may be achieved are provided in the following blog post:

MySQL Performance Tuning - Plesk