presto-main/src/main/java/io/prestosql/operator/PagesIndex.java/PagesIndex/calculateEstimatedSize
class PagesIndex:    private long calculateEstimatedSize()
    {
        long elementsSize = (channels.length > 0) ? sizeOf(channels[0].elements()) : 0;
        long channelsArraySize = elementsSize * channels.length;
        long addressesArraySize = sizeOf(valueAddresses.elements());
        return INSTANCE_SIZE + pagesMemorySize + channelsArraySize + addressesArraySize;
    }