):
        """Initialize with Rockset client.
        Args:
            client: Rockset client object.
            query: Rockset query object.
            content_keys: The collection columns to be written into the `page_content`
                of the Documents.
            metadata_keys: The collection columns to be written into the `metadata` of
                the Documents. By default, this is all the keys in the document.
            content_columns_joiner: Method that joins content_keys and its values into a
                string. It's method that takes in a List[Tuple[str, Any]]],
                representing a list of tuples of (column name, column value).
                By default, this is a method that joins each column value with a new
                line. This method is only relevant if there are multiple content_keys.
        """
        try:
            from rockset import QueryPaginator, RocksetClient
            from rockset.models import QueryRequestSql
        except ImportError:
            raise ImportError(
                "Could not import rockset client python package. "
                "Please install it with `pip install rockset`."
            )
        if not isinstance(client, RocksetClient):
            raise ValueError(
                f"client should be an instance of rockset.RocksetClient, "
                f"got {type(client)}"
            )
        if not isinstance(query, QueryRequestSql):
            raise ValueError(
                f"query should be an instance of rockset.model.QueryRequestSql, "
                f"got {type(query)}"
            )
        self.client = client
        self.query = query
        self.content_keys = content_keys
        self.content_columns_joiner = content_columns_joiner
        self.metadata_keys = metadata_keys
        self.paginator = QueryPaginator
        self.request_model = QueryRequestSql
        try: