def execute(self, query):
        """Executes a query, returning an iterator of resulting rows."""
        cursor = self._connection.cursor(convert=False)
        cursor.execute(query)
        if cursor.description:
            #column_names = [column[0] for column in cursor.description]
            #for row in cursor:
            #    yield row
            while True:
                chunk = cursor.fetchmany(256)
                if chunk:
                    yield chunk
                else:
                    return