SHRINE uses MariaDB by default. SHRINE supports MS SQL and Oracle as well. Best practices for databases recommend a separate database server with backups and fail-overs. Many institutions have policies which require that configuration. That said SHRINE's database needs are modest enough to run MariaDB on the same operating system.
A minimal SHRINE system will need to install MariaDB. For more information on MariaDB, please visit: http://mariadb.org/ . The procedure is:
Increase the number of connections to mariadb from the default 151 to at minimum 2049. In /etc/my.cnf add a max_connnections value.
After this, you will need to create the SHRINE database user and grant it full access: