def _query_iterator(self, result, chunksize, columns, coerce_float=True,<EOL>parse_dates=None):
while True:<EOL><INDENT>data = result.fetchmany(chunksize)<EOL>if not data:<EOL><INDENT>break<EOL><DEDENT>else:<EOL><INDENT>self.frame = DataFrame.from_records(<EOL>data, columns=columns, coerce_float=coerce_float)<EOL>self._harmonize_columns(parse_dates=parse_dates)<EOL>if self.index is not None:<EOL><INDENT>self.frame.set_index(self.index, inplace=True)<EOL><DEDENT>yield self.frame<EOL><DEDENT><DEDENT>
Return generator through chunked result set.