"tables-on-tables" schema

CREATE TABLE Entity (
  id     INTEGER PRIMARY KEY,
  name   VARCHAR(100),
  schema VARCHAR(400)
);

CREATE TABLE FIELD (
  id        INTEGER PRIMARY KEY,
  entity_id INTEGER REFERENCES Entity(id),
  TYPE      VARCHAR(20),
  name      VARCHAR(100)
);


CREATE TABLE Instance (
  id        INTEGER PRIMARY KEY,
  entity_id INTEGER REFERENCES Entity(id),
  DATA      BLOB
);


CREATE TABLE InstanceField (
  id          INTEGER PRIMARY KEY,
  field_id    INTEGER REFERENCES FIELD(id),
  instance_id INTEGER REFERENCES Instance(id),
  VALUE       VARCHAR(100)
);