> a great solution would allow me to pick row-vs-column storage on a per-table b...

> a great solution would allow me to pick row-vs-column storage on a per-table basis ... and do some in-context computations to decide where to walk to next on the graph

You may be interested in Datomic[0] or Datascript[1]

[0]: https://www.datomic.com/benefits.html

[1]: https://github.com/tonsky/datascript