There are many "built-in" softwares for OpenBSD, ex.: NTP, LDAP, RADIUS, etc., see all (?):
in the rc.conf file.
The question: Currently, 2017 Dec, I cannot find any database software by default, is this true?
I know I can install several from the ports, but I am searching one that is shipped with the base (and even knows master-master replication).