private void prepareForIndex(QueryTranslatorImpl q) throws QueryException {

    QueryableCollection collPersister = q.getCollectionPersister(collectionRole);

    if (!collPersister.hasIndex())
      throw new QueryException("unindexed collection before []: " + path);
    String[] indexCols = collPersister.getIndexColumnNames();
    if (indexCols.length != 1) throw new QueryException("composite-index appears in []: " + path);
    // String[] keyCols = collPersister.getKeyColumnNames();

    JoinSequence fromJoins =
        new JoinSequence(q.getFactory())
            .setUseThetaStyle(useThetaStyleJoin)
            .setRoot(collPersister, collectionName)
            .setNext(joinSequence.copy());

    if (!continuation) addJoin(collectionName, collPersister.getCollectionType());

    joinSequence.addCondition(
        collectionName + '.' + indexCols[0] + " = "); // TODO: get SQL rendering out of here

    CollectionElement elem = new CollectionElement();
    elem.elementColumns = collPersister.getElementColumnNames(collectionName);
    elem.elementType = collPersister.getElementType();
    elem.isOneToMany = collPersister.isOneToMany();
    elem.alias = collectionName;
    elem.joinSequence = joinSequence;
    collectionElements.addLast(elem);
    setExpectingCollectionIndex();

    q.addCollection(collectionName, collectionRole);
    q.addFromJoinOnly(collectionName, fromJoins);
  }