hive之array操作_hive array操作

• array_col[n] 取array_col第n个元素，n始自0
• size(array_col) 计算array_col元素个数
• sort_array(array_col) 对array_col中元素进行升序排序，不可指定降序 --select sort_array(array('a','b','a'))
• array_contains(array_col,x) 检索array_col中是否包含x元素，若包括则为true，否则false

一个SQL让你认识array相关函数~~~come on~

with tmp as 
(
    select t.node,t.parent,collect_set(parent) over() as parent_set --就是一个array类型数据
    from 
    (
    select 4 as node,2 as parent 
    union all select 5 as node,2 as parent 
    union all select 6 as node,3 as parent 
    union all select 7 as node,3 as parent 
    union all select 2 as node,1 as parent 
    union all select 3 as node,1 as parent 
    union all select 1 as node,null as parent 
    ) t 
)
select node,parent,parent_set
,parent_set[0] --取array中第一个值
,sort_array(parent_set) --对array进行排序，只能升序，不能指定降序
,size(parent_set) --对array计数
,array_contains(parent_set,node) --检索array中是否有当前node
from tmp

结果