docs: @Override
    public MultipleObjectsBundle delete(DBIDs ids) {
      // Prepare bundle to return
      MultipleObjectsBundle bundle = new MultipleObjectsBundle();
      for(Relation<?> relation : relations) {
        ArrayList<Object> data = new ArrayList<>(ids.size());
        for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
          data.add(relation.get(iter));
        }
        bundle.appendColumn(relation.getDataTypeInformation(), data);
      }
      // remove from db
      for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        doDelete(iter);
      }
      // fire deletion event
      eventManager.fireObjectsRemoved(ids);
  
      return bundle;
    }