docs: private Database buildDerivatorDB(Relation<ParameterizationFunction> relation, CASHInterval interval) {
      DBIDs ids = interval.getIDs();
      ProxyDatabase proxy = new ProxyDatabase(ids);
      int dim = dimensionality(relation);
      SimpleTypeInformation<DoubleVector> type = new VectorFieldTypeInformation<>(DoubleVector.FACTORY, dim);
      WritableDataStore<DoubleVector> prep = DataStoreUtil.makeStorage(ids, DataStoreFactory.HINT_HOT, DoubleVector.class);
  
      // Project
      for(DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        prep.put(iter, DoubleVector.wrap(relation.get(iter).getColumnVector()));
      }
  
      if(LOG.isDebugging()) {
        LOG.debugFine("db fuer derivator : " + ids.size());
      }
  
      MaterializedRelation<DoubleVector> prel = new MaterializedRelation<>(type, ids, null, prep);
      proxy.addRelation(prel);
      return proxy;
    }