def _write_local_schema_file(self, cursor):
        """
        
        """
        schema_str = None
        schema_file_mime_type = 'application/json'
        tmp_schema_file_handle = NamedTemporaryFile(delete=True)
        if self.schema is not None and isinstance(self.schema, string_types):
            schema_str = self.schema.encode('utf-8')
        elif self.schema is not None and isinstance(self.schema, list):
            schema_str = json.dumps(self.schema).encode('utf-8')
        else:
            schema = []
            for field in cursor.description:
                # See PEP 249 for details about the description tuple.
                field_name = field[0]
                field_type = self.type_map(field[1])
                # Always allow TIMESTAMP to be nullable. MySQLdb returns None types
                # for required fields because some MySQL timestamps can't be
                # represented by Python's datetime (e.g. 0000-00-00 00:00:00).
                if field[6] or field_type == 'TIMESTAMP':
                    field_mode = 'NULLABLE'
                else:
                    field_mode = 'REQUIRED'
                schema.append({
                    'name': field_name,
                    'type': field_type,
                    'mode': field_mode,
                })
            schema_str = json.dumps(schema, sort_keys=True).encode('utf-8')
        tmp_schema_file_handle.write(schema_str)

        self.log.info('Using schema for %s: %s', self.schema_filename, schema_str)
        schema_file_to_upload = {
            'file_name': self.schema_filename,
            'file_handle': tmp_schema_file_handle,
            'file_mime_type': schema_file_mime_type
        }
        return schema_file_to_upload