Hive内置集合函数-size,map_keys,map_values,sort_array,array_contains

1. Hive内置Collection Functions

以下函数为Hive是提供的内置集合函数:

返回类型	函数(签名)	函数说明
int	size(Map<K.V>)	Returns the number of elements in the map type.
int	size(Array)	Returns the number of elements in the array type.
array	map_keys(Map<K.V>)	Returns an unordered array containing the keys of the input map.
array	map_values(Map<K.V>)	Returns an unordered array containing the values of the input map.
boolean	array_contains(Array, value)	Returns TRUE if the array contains value.
array	sort_array(Array)	Sorts the input array in ascending order according to the natural ordering of the array elements and returns it (as of version 0.9.0).

2. 测试Collection Functions

with tmp_map_data as (
    select map(
                   "k2", "v2", 
                   "k1", "v1", 
                   "k3", "v3"
           ) as m
    )
select
    size(m),								-- 3
    map_keys(m),							-- ["k1","k2","k3"]
    map_values(m),							-- ["v2","v1","v3"]
    sort_array(map_keys(m)),				-- ["k1","k2","k3"]
    array_contains(map_keys(m), 'k3'),		-- true
    array_contains(map_keys(m), 'k4')		-- false
from tmp_map_data;

3. 说明

Hive提供的内置集合函数, 在做一些集合内统计/查找/分析等场景下非常方便, 熟练使用, 可以极大的简化这类场景的开发.

参考文献:

• Hive UDF > CollectionFunctions