Looking Back at Postgres by Joseph M. Hellerstein (available here: https://arxiv.org/abs/1901.01973 ) is an easy to read, general paper on the Postgres development. It details, the design of Postgres database, and provides the details on multiple inflection points into it's development. The very paragraph caught my attention.
Michael Stonebraker was the lead, and the designer of this system. But never wrote the code for this system, all coding was done by students, and university programmers. Postgres, followed Michael Stonebraker's first system Ingres, and turned out to be successful database system, that is now being developed by community of open source developers.