presto-spi/src/main/java/io/prestosql/spi/block/LazyBlock.java/LazyBlock/getRegionSizeInBytes
class LazyBlock:    @Override
    public long getRegionSizeInBytes(int position, int length)
    {
        if (!isLoaded()) {
            return 0;
        }
        return getBlock().getRegionSizeInBytes(position, length);
    }