MySQL / MariaDB max_open_files more than 1024

For me the issue was MySQL max_open_files more than 1024https://unix.stackexchange.com/questions/152186/mysql-max-open-files-more-than-1024

Edit /etc/security/limits.conf and add the following lines

mysql soft nofile 65535
mysql hard nofile 65535

then reboot.

Then edit /etc/systemd/system/mysqld.service and add

LimitNOFILE=infinity
LimitMEMLOCK=infinity

Then restart the db service:

sudo systemctl reload mariadb.service