@Override
    public int compareTo(Hit other) {
        int cmpRes = 0;
        if ((sortData != null) && (other instanceof FastHit) && hasSortData(((FastHit) other).sortDataSorting)) {
            cmpRes =  SortDataHitSorter.getComparator(sortDataSorting, null).compare(this, other);
        }
        return (cmpRes != 0) ? cmpRes : super.compareTo(other);
    }
Sets the index of the node this hit originated at
container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java