Documentation for MariaDB says clearly how to set up server defaults like charset and collation. So I opened my Mariadb console and run:
SET character_set_server = 'utf8mb4';
SET collation_server = 'utf8mb4_slovak_ci';
Consoles wrote OK. Then I restart the server, but as I tried to create new database there are still the same latin2 charset and swedish collation. I do it automatically via Symfony cosole command
php bin/console doctrine:database:create
What is wrong with that? I did it like documentation says.