docs: def identity(self):
          """Return this partition information as a PartitionId."""
  
          if self.dataset is None:
              # The relationship will be null until the object is committed
              s = object_session(self)
  
              ds = s.query(Dataset).filter(Dataset.id_ == self.d_id).one()
          else:
              ds = self.dataset
  
          d = {
              'id': self.id,
              'vid': self.vid,
              'name': self.name,
              'vname': self.vname,
              'ref': self.ref,
              'space': self.space,
              'time': self.time,
              'table': self.table_name,
              'grain': self.grain,
              'variant': self.variant,
              'segment': self.segment,
              'format': self.format if self.format else 'db'
          }
  
          return PartitionIdentity.from_dict(dict(list(ds.dict.items()) + list(d.items())))