MySQL 5.5 on Plesk shows warning: Using unique option is deprecated and will be removed in a future release

Symptoms

1. MySQL 5.5 is installed on Plesk server. 
2. Errors in /var/log/mysql/error.log or /var/log/mysql.log:

   Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
    
    Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.

Cause


key_buffer
and
myisam-recover
are deprecated in MySQL 5.5.


myisam-recover
option is renamed as of MySQL 5.5.3 to
myisam-recover-options
.

Resolution

Note: This article may require additional administrative knowledge to apply. If any help is required, contact server’s administrator or hosting support.

1. Log in to Plesk server via SSH
2. Rename the options in /etc/my.cnf or /etc/mysql/my.cnf as below using vi editor:

   key_buffer_size = 16M
    myisam-recover-options = BACKUP

3. Restart MySQL server:

   # service mysql restart || systemctl restart mariadb || service mysqld restart