custom_index (Optional `faiss.Index`): Custom Faiss index that you already have instantiated and configured for your needs.
            batch_size (Optional `int`): Size of the batch to use while adding vectors to the FaissIndex. Default value is 1000.
                <Added version="2.4.0"/>
            train_size (Optional `int`): If the index needs a training step, specifies how many vectors will be used to train the index.
            faiss_verbose (`bool`, defaults to False): Enable the verbosity of the Faiss index.
        """
        faiss_index = FaissIndex(
            device=device, string_factory=string_factory, metric_type=metric_type, custom_index=custom_index
        )
        faiss_index.add_vectors(
            external_arrays, column=None, batch_size=batch_size, train_size=train_size, faiss_verbose=faiss_verbose
        )
        self._indexes[index_name] = faiss_index