SortBuilders.fieldSort(OpenSearchUrlQueue.WEIGHT).order(SortOrder.DESC),
                SortBuilders.fieldSort(CREATE_TIME).order(SortOrder.ASC));
    }

    @Override
    public void saveSession(final String sessionId) {
        // TODO use cache
    }

    @Override
    public boolean visited(final OpenSearchUrlQueue urlQueue) {
        final String url = urlQueue.getUrl();