[mwhite]

Sorry for being unclear. I'm not proposing NoSQL. I'm saying that many NoSQL users really mainly want NoDDL, which can be implemented on top of Postgres JSON storage while retaining SQL.

- data (string type, int id, json fields)

- fk (string type, int subj_id, int obj_id)

  select
    data.id,
    data.fields,
    fk_1.obj_id as 'foo_id'
    fk_2.obj_id as 'bar_id'
  from data
  join fk as fk_1 on data.id = fk_1.subj_id
  join fk as fk_2 on data.id = fk_2.subj_id
  where 
    data.type = 'my_table'
    and fk_1.type = 'foo'
    and fk_2.type = 'bar'

What would the performance characteristics of that be versus if "foreign keys" are stored in the same table as the data, if fk has the optimal indexes?