Your padding + deduplication solution is nice. > Edit: If you used the ID of the last item instead of an offset, then you could get errors if your last item is

Your padding + deduplication solution is nice. > Edit: If you used the ID of the last item instead of an offset, then you could get errors if your last item is in fact the one that was deleted. If the items are sorted by ID, then we use the ID of the last item x. But for example if they are sorted by timestamp, then we use the timestamp of the last item (and maybe the ID to break ties). Then it doesn't matter if the last item is still there or not. We are only considering values before or after depending on the sort order.