presto-spi/src/main/java/io/prestosql/spi/type/RowType.java/RowType/hash
class RowType:    @Override
    public long hash(Block block, int position)
    {
        Block arrayBlock = block.getObject(position, Block.class);
        long result = 1;
        for (int i = 0; i < arrayBlock.getPositionCount(); i++) {
            Type elementType = fields.get(i).getType();
            result = 31 * result + TypeUtils.hashPosition(elementType, arrayBlock, i);
        }
        return result;
    }