I am not sure I follow the conversation. What would a deeply nested result hierarchy be, exactly?
Are we talking about something like:
CREATE TABLE person (id INT, name TEXT, birthdate DATE);
CREATE TABLE car (id INT, brand TEXT, model TEXT, licence TEXT);
CREATE TABLE p_c (pid INT, cid INT, FOREIGN KEY pid REFERENCES person (id), FOREIGN KEY cid REFERENCES car (id));
And for a given person, we want to return their details plus the cars they own?
gopher://example.com/person/{id}
# Get person ID
1, Joe, 1970-01-01
gopher://example.com/car/{id}
# Get car ID
1, Ford, T, 1313
gopher://example.com/person/{id}/cars
# Get all cars owned by person ID
1, Joe, 1970-01-01, 1 Ford, T, 1313
,,, 2 Ford, S, 1717
gopher://example.com/person/{id}/cars/{id}
# Get specific car
gopher://example.com/car/{id}/owners
# Get owner(s) of car ID
gopher://example.com/car/{id}/owners/{id}
# Get specific owner
gopher://example.com/car/{id}/owners/{id}/birthdate
# Get specific owner's birthdate
gopher://example.com/car/{id}/owners/birthdate
# Get birthdate of all owners (assuming no domain overlap between IDs and field names, other solutions possible otherwise)
If this is the sort of thing we're talking about, I've got that t-shirt and assumed everyone had too, so I guess I'm missing the point here. By how much?