提取SQL中的数组的最后N个元素（配置单元）

Question

我有一列包含数组，我想提取数组中的最后X个元素。

示例尝试提取最后两个元素：

     Column A
     ['a', 'b', 'c']
     ['d', 'e']
     ['f', 'g', 'h', 'i']

预期输出：

     Column A
    ['b', 'c']
    ['d', 'e']
    ['h', 'i']

最好的情况是不使用UDF进行操作

Answer 1

再次使用反向，爆炸，过滤和重新组装数组的一种方法：

with your_table as (
select stack (4,
0, array(), --empty array to check it works if no elements or less than n
1, array('a', 'b', 'c'),
2, array('d', 'e'),
3, array('f', 'g', 'h', 'i')
) as (id, col_A)
)

select s.id, collect_list(s.value) as col_A 
from
(select s.id, a.value, a.pos
  from your_table s
       lateral view outer posexplode(split(reverse(concat_ws(',',s.col_A)),',')) a as pos, value
where a.pos between 0 and 1 --last two (use n-1 instead of 1 if you want last n)  
distribute by s.id sort by a.pos desc --keep original order
)s
group by s.id

结果：
s.id    col_a
0   []
1   ["b","c"]
2   ["d","e"]
3   ["h","i"]

也许不雅致，但仅使用内置函数