Beagle SQL was an object-relational DBMS from the 1990s.
The project was abandoned in 1999. The source code for the last last version was copied to Github.
Relational Object-Relational
SQL
Disk-oriented
N-ary Storage Model (Row/Record)
Shared-Everything
http://www.beaglesql.org/
https://github.com/jonahharris/osdb-beaglesql
http://www.beaglesql.org/docs/
Robert Klein, Jean-Claude Magras
US
1996
1999
Open Source
C++