presto-main/src/main/java/io/prestosql/operator/SortedPositionLinks.java/SortedPositionLinks/sizeOfPositionLinks
class SortedPositionLinks:    private long sizeOfPositionLinks(int[][] sortedPositionLinks)
    {
        long retainedSize = sizeOf(sortedPositionLinks);
        for (int[] element : sortedPositionLinks) {
            retainedSize += sizeOf(element);
        }
        return retainedSize;
    }