Hive, ordering lines using a variable lag - sql

Question

I have the following hive table:
product | price
A | 100
B | 102
C | 220
D | 240
E | 242
F | 410
For every line I would like to divide the lower price by the current price, if the result is greater than 0.9 I would like to increments a row number. If the result is lower than 0.9 then row number should be 1 for this line, and current price become lower price, then iterate.
Result should look like:
product | price | row_number
A | 100 | 1
B | 102 | 2
C | 220 | 1
D | 240 | 2
E | 242 | 3
F | 410 | 1
Because:
lower price = 100: product A get 1 as row_number
100/102 >= 0.9: product B get 2 as row_number
100/220 < 0.9: product C get 1 as row_number, lower price = 220
220/240 >= 0.9: product D get 2 as row_number
220/242 >= 0.9: product E get 3 as row_number
220/410 < 0.9: product F get 1 as row_number, lower price = 410
I was thinking about creating a temporary_row_number just ordered by price:
product | price | temp_row_number
A | 100 | 1
B | 102 | 2
C | 220 | 3
D | 240 | 4
E | 242 | 5
F | 410 | 6
And then:
Select
product,
price,
case
when lag(price,temp_row_number-1,0)/price over() >= 0.9 then lag(price,temp_row_number-1,0)
else price
end as test
from my_table
This will retrieve:
product | price | test
A | 100 | 100
B | 102 | 100
C | 220 | 220
D | 240 | 240
E | 242 | 242
F | 410 | 410
But ideally I would like to retrieve
product | price | test
A | 100 | 100
B | 102 | 100
C | 220 | 220
D | 240 | 220
E | 242 | 220
F | 410 | 410
So I could compute row_number row using the row_number() function order by product and price and get the expected result.

Answer 1

WITH CTE
AS
(select product,price,(case when price between 100 and 200 then 1
when price between 200 and 300 then 2
when price between 300 and 400 then 3 END ) AS RN
FROM #test)
SELECT Product,Price, ROW_NUMBER() OVER (PARTITION BY RN ORDER BY RN) FROM CTE
ORDER BY Product