Impala compare consecutive rows and insert identical row if there are no values

Question

I have a table that gives me data every month and I need that range of time. I noticed that sometimes I don't have data for 3/4 month but I need to duplicate the last row available with the missing timestamp.

Example:

product_id	total_revenue	yearmonth
1	50	202201
2	17	202201
3	30	202201
1	67	202202
2	31	202202
1	67	202203
2	31	202203
3	33	202203

But I need an output like:

product_id	total_revenue	yearmonth
1	50	202201
2	17	202201
3	30	202201
1	67	202202
2	31	202202
3	30	202202
1	67	202203
2	31	202203
3	33	202203

I have a select statement like:

select 
    product_id, total_revenue, yearmonth 
from 
    revenue

I found a similar question, (Postgresql compare consecutive rows and insert identical row if there are no values) but in Impala I have not the lateral join, does anybody know how can I do?

Answer 1

I did it!

with crossed as
(
select
product_id,id_month,
rank() over (partition by product_id order by id_month asc) as r
from
(
select distinct cast(id_month as string) as id_month
from calendar d
where day_data <= date_sub(now(), interval 1 month)
) a
cross join
(select product_id, min(concat(year,month)) as minimum
from revenue
group by product_id
) b
where a.id_month >= b.minimum
)
, created as
(
select
coalesce(a.product_id,b.product_id) as product_id,
coalesce(concat(a.year,a.month),b.id_month) as id_month,
a.total_revenue,
b.r
from revenue a
full outer join crossed b
on a.product_id=b.product_id and concat(a.year,a.month)=b.id_month
where a.year is null
)
,
real as
(
select
coalesce(a.product_id,b.product_id) as product_id,
coalesce(concat(a.year,a.month),b.id_month) as id_month,
a.total_revenue,
b.r
from revenue a
full outer join crossed b
on a.product_id=b.product_id and concat(a.year,a.month)=b.id_month
where a.year is not null
)
select product_id,id_month,total_revenue,'CREATED' as tipe
from
(
select created.product_id,created.id_month,real.total_revenue,
rank () over (partition by created.product_id,created.id_month order by (created.r-real.r) asc) as r
from
created left join real on created.product_id=real.product_id
and created.id_month > real.id_month
)a
where r=1
union
select product_id,concat(year,month) as id_month,total_revenue,'REAL' as tipe
from revenue