code: def _query_iterator(cursor, chunksize, columns, index_col=None,
                          coerce_float=True, parse_dates=None):
          
  
          while True:
              data = cursor.fetchmany(chunksize)
              if type(data) == tuple:
                  data = list(data)
              if not data:
                  cursor.close()
                  break
              else:
                  yield _wrap_result(data, columns, index_col=index_col,
                                     coerce_float=coerce_float,
                                     parse_dates=parse_dates)
docs: Return generator through chunked result set