presto-main/src/main/java/io/prestosql/operator/PagesIndex.java/PagesIndex/sort
class PagesIndex:    public void sort(List<Integer> sortChannels, List<SortOrder> sortOrders, int startPosition, int endPosition)
    {
        createPagesIndexComparator(sortChannels, sortOrders).sort(this, startPosition, endPosition);
    }