The Association for Computing Machinery's publication, ACM Queue, had Kirk McKusick of FreeBSD fame interview Margo Seltzer and Mike Olson about the development of BerkeleyDB [acm.org]. The two, along with Keith Bostic, have been awarded the 2020 ACM Software System Award [acm.org] for the database. BerkeleyDB is a dual-licensed (AGPL and proprietary), simple, efficient, transactional, nosql database and currently maintained by Oracle.
Kirk McKusick: Berkeley DB came out of the University of California at Berkeley Computer Systems Research Group's work to create a version of Unix unencumbered by AT&T's ownership rights to the original version of Unix. To do that, we needed a new kernel, written without using any of the AT&T code. We also needed all the applications and libraries that shipped with the operating system.
My colleague on the Berkeley BSD Project, Mike Karels, and I were in charge of getting a clean version of the kernel—that's another story! But Keith Bostic took on the task of getting all the apps and libraries done. He solicited volunteers for much of that work. I know he worked with you two on that. Why don't you start the story there?
BerkeleyDB has been around since 1991 and can be found in many places, including inside OpenLDAP. In its 30 years, it has raised public awareness of non-relational databases. It is in general one of the more useful, reliable, and long-lived software projects around.