how to include 0 results in count with group by in HIVEQL

Question

I'm a newbie in HIVE. I want to include 0 rows in results

I have one table like

- - - - - - - - - - - - - - -
data_source_id,  part_hour, ...
- - - - - - - - - - - - - - -

this is my query

SELECT data_source_id, COUNT(*) as count 
FROM data_source 
WHERE part_hour = 2022041618 
GROUP BY data_source_id;

example result is

data_source_id, count
12            , 35
13            , 36

but my desired result is

data_source_id, count
12            , 35
13            , 36
15.           , 0
        

How can I get a 0 in results?

Answer 1

You can do this but you need to remove where clause.

SELECT data_source_id, 
SUM(case when part_hour = 2022041618 then 1 else 0 end ) as count 
FROM data_source  
GROUP BY data_source_id;

You can also do using self join.

EDIT - I changed below SQL as per your need. If you have partitions on part hour and data_source_id, your SQL should be quick.

select distinct d.data_source_id, nvl(rs.count,0) 
FROM 
(select distinct data_source_id from data_source) d
left join (SELECT data_source_id, COUNT(*) as count 
FROM data_source 
WHERE part_hour = 2022041618 
GROUP BY data_source_id) rs on rs.data_source_id=d.data_source_id;