按位置映射3个数组列的配置单元查询 [英] Hive query to map 3 array columns position wise

问题描述

i/p:

c1                        c2                        c3
[[1,2,3],[4],[5,6]]       ['v1','v2','v3']          [['sam'], ['tam'], ['bam']] 

o/p:

c1                        c2                        c3
[1,2,3]                   'v1'                      ['sam']
[4]                       'v2'                      ['tam']
[5,6]                     'v3'                      ['bam']

有人能建议我如何开始为上述问题编写查询吗？

推荐答案

使用POST EXPLODE()：

with your_data as (
select array(array(1,2,3),array(4),array(5,6)) c1, array('v1','v2','v3') c2, array(array('sam'), array('tam'), array('bam')) c3
--returns [[1,2,3],[4],[5,6]]  ["v1","v2","v3"]  [["sam"],["tam"],["bam"]]
)

select a1.c1, a2.c2, a3.c3
  from your_data d 
       lateral view posexplode(d.c1) a1 as p1, c1
       lateral view posexplode(d.c2) a2 as p2, c2
       lateral view posexplode(d.c3) a3 as p3, c3
 where a1.p1=a2.p2 and a1.p1=a3.p3 --match positions in exploded arrays
 --without this where condition
 --lateral views will produce cartesian product
 --alternatively you can explode arrays in subqueries and join them
 --using positions, in such way you can do left-join, not only inner
 ;

结果：

OK
c1      c2      c3
[1,2,3] v1      ["sam"]
[4]     v2      ["tam"]
[5,6]   v3      ["bam"]
Time taken: 0.078 seconds, Fetched: 3 row(s)

简化版，感谢@GrzegorzSkibinski的建议：

with your_data as (
    select array(array(1,2,3),array(4),array(5,6)) c1, array('v1','v2','v3') c2, array(array('sam'), array('tam'), array('bam')) c3
    --returns [[1,2,3],[4],[5,6]]  ["v1","v2","v3"]  [["sam"],["tam"],["bam"]]
    )

    select a1.c1, d.c2[a1.p1] as c2,  d.c3[a1.p1] as c3
      from your_data d 
           lateral view posexplode(d.c1) a1 as p1, c1
     ;

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