Add official source

sudo apt-get install software-properties-common
sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
sudo add-apt-repository "deb [arch=amd64,arm64,ppc64el] http://mariadb.mirror.liquidtelecom.com/repo/10.4/ubuntu $(lsb_release -cs) main"

Install MariaDB 10.4

sudo apt-get update
sudo apt-get install mariadb-server mariadb-client
sudo systemctl enable mariadb.service
sudo mysql_secure_installation

Edit config

sudo vi /etc/mysql/my.cnf

log_error               = /var/log/mysql/error.log
log_warnings            = 2
slow_query_log          = 1
slow_query_log_file     = /var/log/mysql/slow.log
long_query_time         = 3

(optional)

bind-address = 0.0.0.0
wait_timeout = 60
max_allowed_packet = 32M            # default 16M
innodb_buffer_pool_size = 512M      # default 256M

Create user

CREATE USER 'USERNAME'@'localhost' IDENTIFIED BY 'PASSWORD';
GRANT ALL PRIVILEGES ON *.* TO 'USERNAME'@'localhost' WITH GRANT OPTION;

Useful Command

sudo systemctl stop mysql
sudo systemctl start mysql
sudo systemctl status mysql
sudo systemctl restart mysql