Take a look at http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.113.5640 http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.113.... . Object databas

Take a look at http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.113.5640 http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.113.... . Object databases, XML databases and network databases were around long before relational databases. The key problem the relational databases solved is not having to bake the access paths into your data-structure.