hive - split a row into multiple rows between the range of values

Question

I have a table below and would like to split the rows by the range from start to end columns.

i.e id and value should repeat for each value between start & end(both inclusive)

--------------------------------------
id      | value   | start     | end
--------------------------------------
1       | 5       | 1         | 4
2       | 8       | 5         | 9
--------------------------------------

Desired output

--------------------------------------
id      | value   | current
--------------------------------------
1       | 5       | 1
1       | 5       | 2
1       | 5       | 3
1       | 5       | 4

2       | 8       | 5
2       | 8       | 6
2       | 8       | 7
2       | 8       | 8
2       | 8       | 9
--------------------------------------

I can write my own UDF in java/python to get this result but would like to check if I can implement in Hive SQL using any existing hive UDFs

Thanks in advance.

Answer 1

This can be accomplished with a recursive common table expression, which Hive doesn't support.

One option is to create a table of numbers and use it to generate rows between start and end.

create table numbers
location 'hdfs_location' as 
select row_number() over(order by somecolumn) as num
from some_table --this can be any table with the desired number of rows 
;

--Join it with the existing table 
select t.id,t.value,n.num as current
from tbl t
join numbers n on n.num>=t.start and n.num<=t.end

Answer 2

You can do using posexplode() UDF.

WITH
data AS (
  SELECT 1 AS id, 5 AS value, 1 AS start, 4 AS `end`
  UNION ALL
  SELECT 2 AS id, 8 AS value, 5 AS start, 9 AS `end`
)
SELECT distinct id, value, (zr.start+rge.diff) as `current`
   FROM data zr LATERAL VIEW posexplode(split(space(zr.`end`-zr.start),' ')) rge as diff, x

Here is its Output:

+-----+--------+----------+--+
| id  | value  | current  |
+-----+--------+----------+--+
| 1   | 5      | 1        |
| 1   | 5      | 2        |
| 1   | 5      | 3        |
| 1   | 5      | 4        |
| 2   | 8      | 5        |
| 2   | 8      | 6        |
| 2   | 8      | 7        |
| 2   | 8      | 8        |
| 2   | 8      | 9        |
+-----+--------+----------+--+