presto-spi/src/main/java/io/prestosql/spi/type/LongDecimalType.java/LongDecimalType/getSlice
class LongDecimalType:    @Override
    public Slice getSlice(Block block, int position)
    {
        return Slices.wrappedLongArray(
                block.getLong(position, 0),
                block.getLong(position, SIZE_OF_LONG));
    }