使用 Hive 炸裂函数 explode (map<string,string>) 宽表转高表

一个会写诗的程序员

发布于 2021-12-24 06:34:57

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Hive 炸裂函数 explode(map<string,string>) 宽表转高表SQL:

select  
slice_id,
user_id,
shop_id,
'user_stats_public' as table_code,
explode(kv) as (field_code,field_value)
from 
(   select 
    user_id,
    -1 as shop_id,
    abs(hash(user_id) % 20000) as  slice_id, 
    map(
    'residence_city_name',residence_city_name,
    'residence_city_level',residence_city_level,
    'gender', gender,
    'age', age,
    'activeness_level' , activeness_level,
    'consuming_level' , consuming_level,
    'pay_amt_td_level' , pay_amt_td_level,
    'old_ecom_user' , old_ecom_user
    ) as kv
from  ecom_kunlun.types_mapping_table_13_1639904624993 
where date = max_pt('ecom_kunlun.types_mapping_table_13_1639904624993') ) a;

explode() : Usage Examples

explode (array)

select explode(array('A','B','C'));
select explode(array('A','B','C')) as col;
select tf.* from (select 0) t lateral view explode(array('A','B','C')) tf;
select tf.* from (select 0) t lateral view explode(array('A','B','C')) tf as col;

explode (map)

select explode(map('A',10,'B',20,'C',30));
select explode(map('A',10,'B',20,'C',30)) as (key,value);
select tf.* from (select 0) t lateral view explode(map('A',10,'B',20,'C',30)) tf;
select tf.* from (select 0) t lateral view explode(map('A',10,'B',20,'C',30)) tf as key,value;

posexplode (array)

select posexplode(array('A','B','C'));
select posexplode(array('A','B','C')) as (pos,val);
select tf.* from (select 0) t lateral view posexplode(array('A','B','C')) tf;
select tf.* from (select 0) t lateral view posexplode(array('A','B','C')) tf as pos,val;

inline (array of structs)

select inline(array(struct('A',10,date '2015-01-01'),struct('B',20,date '2016-02-02')));
select inline(array(struct('A',10,date '2015-01-01'),struct('B',20,date '2016-02-02'))) as (col1,col2,col3);
select tf.* from (select 0) t lateral view inline(array(struct('A',10,date '2015-01-01'),struct('B',20,date '2016-02-02'))) tf;
select tf.* from (select 0) t lateral view inline(array(struct('A',10,date '2015-01-01'),struct('B',20,date '2016-02-02'))) tf as col1,col2,col3;

stack (values)

select stack(2,'A',10,date '2015-01-01','B',20,date '2016-01-01');
select stack(2,'A',10,date '2015-01-01','B',20,date '2016-01-01') as (col0,col1,col2);
select tf.* from (select 0) t lateral view stack(2,'A',10,date '2015-01-01','B',20,date '2016-01-01') tf;
select tf.* from (select 0) t lateral view stack(2,'A',10,date '2015-01-01','B',20,date '2016-01-01') tf as col0,col1,col2;

Using the syntax "SELECT udtf(col) AS colAlias..." has a few limitations:

No other expressions are allowed in SELECT
- SELECT pageid, explode(adid_list) AS myCol... is not supported
UDTF's can't be nested
- SELECT explode(explode(adid_list)) AS myCol... is not supported
GROUP BY / CLUSTER BY / DISTRIBUTE BY / SORT BY is not supported
- SELECT explode(adid_list) AS myCol ... GROUP BY myCol is not supported

Please see LanguageManual LateralView for an alternative syntax that does not have these limitations.

Also see Writing UDTFs if you want to create a custom UDTF.