PostgreSQL Current count of specific value - sql

Question

I need to achieve a view such as:
+------------+----------+--------------+----------------+------------------+
| Parent id | Expected | Parent Value | Distinct Value | Distinct Value 2 |
+------------+----------+--------------+----------------+------------------+
| 1 | 001.001 | 3 | 6/1/2017 | 5,000.00 |
| 1 | 001.002 | 3 | 9/1/2018 | 3,500.00 |
| 1 | 001.003 | 3 | 1/7/2018 | 9,000.00 |
| 2 | 002.001 | 7 | 9/1/2017 | 2,500.00 |
| 3 | 003.001 | 5 | 3/6/2017 | 1,200.00 |
| 3 | 003.002 | 5 | 16/8/2017 | 8,700.00 |
+------------+----------+--------------+----------------+------------------+
where I get distinct child objects that have same parents, but I cannot make the "Expected" column work. Those zeros don't really matter, I just need to get subindex like "1.1", "1.2" to work. I tried rank() function but it seems it doesnt really help.
Any help appreciated, thanks in advance.
My initial try looks like this:
SELECT DISTINCT
parent.parent_id,
rank() OVER ( order by parent_id ) as expected,
parent.parent_value,
ct.distinct_value,
ct.distinct_value_2
FROM parent
LEFT JOIN (crosstab (...) )
AS ct( ... )
ON ...

Answer 1

Use partition by parent_id in the window function and order by another_col to define the order in groups by parent_id.
with parent(parent_id, another_col) as (
values (1, 30), (1, 20), (1, 10), (2, 40), (3, 60), (3, 50)
)
select
parent_id,
another_col,
format('%s.%s', parent_id, row_number() over w) as expected
from parent
window w as (partition by parent_id order by another_col);
parent_id | another_col | expected
-----------+-------------+----------
1 | 10 | 1.1
1 | 20 | 1.2
1 | 30 | 1.3
2 | 40 | 2.1
3 | 50 | 3.1
3 | 60 | 3.2
(6 rows)