def count(self):
        """
        Returns the number of rows matched by this query.

        *Note: This function executes a SELECT COUNT() and has a performance cost on large datasets*
        """
        if self._batch:
            raise CQLEngineException("Only inserts, updates, and deletes are available in batch mode")

        if self._count is None:
            query = self._select_query()
            query.count = True
            result = self._execute(query)
            count_row = result.one().popitem()
            self._count = count_row[1]
        return self._count
Returns the number of rows matched by this query.

        *Note: This function executes a SELECT COUNT() and has a performance cost on large datasets*