Because of the topic on Hiawatha with a database backend.
The solution would not seem to use SQL rather than No-SQL. Here referring to the latter having the distributed model built-in.
There are amazing products out there of which the wiki page on the topic provides a good cross section. Given the many internetworked features built into these products they would also adhere to the Hiawatha philosophy of not extending the webserver functionality beyond it's goal.https://en.wikipedia.org/wiki/NoSQL
One particular product i have in mind, as an example, is CEPH. Which not only can act as a key-value store but can also export these "records" as a file on a filesystem and vice-versa, once again in a distributed model. Oh yeah.http://ceph.com/docs/master/rados/