other downsides I saw from an implementation of this in postgres: 1.you can't have strongly typed schemas specific to a 'thing' subtype; to store it all togeth

other downsides I saw from an implementation of this in postgres: 1.you can't have strongly typed schemas specific to a 'thing' subtype; to store it all together, you end up sticking all the interesting bits in a JSON field 2. any queries of interest require a lot of self joins and performance craters Please, please, never implement a "graph database" or "party model" or "entity schema" in a normal RDBMS, except perhaps at miniscule scale; the flexibility is absolutely not worth it.