Getting wrong(?) average when calculating values in a time range - sql

Question

I am working with AWS Redshift / PostgreSQL. I have two tables that can be joined on the interval_date (DATE data_type) and interval_time_utc (VARCHAR data type) and/or the status and price_source columns. Source A is equivalent to the Y status and Source B is equivalent to the N status. I am trying to get the average price and the sum of mw_power for a given hour for each status / price_source. An hour is the timestamps from XX:05 to XX:00 so for 15:00, the values should be from the 14:05 to the 15:00 timestamps. Even if for an hour interval where all status are one value, I still need to calculate the average price for both price_source values, but the sum of mw_power would be 0. I am passing in the date and time intervals through my application code. I am seeing a different average price for the 15:00 hour than I expect so either I am bad at math or there is a bug in my query I can't determine. The 14:00 and 16:00 hour results come back as expected.
power_table
interval_date
interval_time_utc
mw_power
status
2022-05-09
13:00
92.25
N
2022-05-09
13:05
90.75
N
2022-05-09
13:10
91.25
N
2022-05-09
13:15
92.00
N
2022-05-09
13:20
92.00
N
2022-05-09
13:25
90.00
N
2022-05-09
13:30
93.00
N
2022-05-09
13:35
91.75
N
2022-05-09
13:40
90.25
N
2022-05-09
13:45
93.00
N
2022-05-09
13:50
91.00
N
2022-05-09
13:55
94.00
N
2022-05-09
14:00
91.00
N
2022-05-09
14:05
91.00
N
2022-05-09
14:10
94.00
N
2022-05-09
14:15
92.00
N
2022-05-09
14:20
91.00
N
2022-05-09
14:25
94.00
Y
2022-05-09
14:30
92.00
Y
2022-05-09
14:35
91.75
Y
2022-05-09
14:40
92.25
Y
2022-05-09
14:45
91.00
Y
2022-05-09
14:50
92.00
Y
2022-05-09
14:55
93.00
Y
2022-05-09
15:00
90.00
Y
price_table
interval_date
interval_time_utc
price
price_source
2022-05-09
13:00
54.20
Source A
2022-05-09
13:05
54.20
Source A
2022-05-09
13:10
54.20
Source A
2022-05-09
13:00
54.20
Source B
2022-05-09
13:05
54.20
Source B
2022-05-09
13:10
54.20
Source B
2022-05-09
13:15
34.11
Source A
2022-05-09
13:20
34.11
Source A
2022-05-09
13:25
34.11
Source A
2022-05-09
13:15
39.61
Source B
2022-05-09
13:20
39.61
Source B
2022-05-09
13:25
39.61
Source B
2022-05-09
13:30
2.81
Source A
2022-05-09
13:35
2.81
Source A
2022-05-09
13:40
2.81
Source A
2022-05-09
13:30
17.13
Source B
2022-05-09
13:35
17.13
Source B
2022-05-09
13:40
17.13
Source B
2022-05-09
13:45
1.58
Source A
2022-05-09
13:50
1.58
Source A
2022-05-09
13:55
1.58
Source A
2022-05-09
13:45
15.98
Source B
2022-05-09
13:50
15.98
Source B
2022-05-09
13:55
15.98
Source B
2022-05-09
14:00
4.60
Source A
2022-05-09
14:05
4.60
Source A
2022-05-09
14:10
4.60
Source A
2022-05-09
14:00
18.09
Source B
2022-05-09
14:05
18.09
Source B
2022-05-09
14:10
18.09
Source B
2022-05-09
14:15
2.46
Source A
2022-05-09
14:20
2.46
Source A
2022-05-09
14:25
2.46
Source A
2022-05-09
14:15
16.66
Source B
2022-05-09
14:20
16.66
Source B
2022-05-09
14:25
16.66
Source B
2022-05-09
14:30
3.36
Source A
2022-05-09
14:35
3.36
Source A
2022-05-09
14:40
3.36
Source A
2022-05-09
14:30
21.52
Source B
2022-05-09
14:35
21.52
Source B
2022-05-09
14:40
21.52
Source B
2022-05-09
14:45
4.55
Source A
2022-05-09
14:50
4.55
Source A
2022-05-09
14:55
4.55
Source A
2022-05-09
14:45
16.30
Source B
2022-05-09
14:50
16.30
Source B
2022-05-09
14:55
16.30
Source B
2022-05-09
15:00
-21.87
Source A
2022-05-09
15:00
4.96
Source B
-- query that i am using to get hourly values
SELECT pricet.price_source,
COALESCE(powert.volume, 0),
pricet.price,
powert.status
FROM (SELECT status,
SUM(mw_power) volume
FROM power_table
WHERE (interval_date || ' ' || interval_time_utc)::timestamp BETWEEN '2022-05-09 14:05:00.0' AND '2022-05-09 15:00:00.0'
GROUP BY status) powert
RIGHT JOIN (SELECT price_source,
AVG(price) price
FROM price_table
WHERE (interval_date || ' ' || interval_time_utc)::timestamp BETWEEN '2022-05-09 14:05:00.0' AND '2022-05-09 15:00:00.0'
GROUP BY price_source) pricet
ON pricet.price_source = CASE WHEN powert.status = 'Y' THEN 'Source A'
ELSE 'Source B'
END;
I am looking to get an expected output of the following for the 15:00 hour:
price_source
volume
price
status
Source A
736.00
0.54
Y
Source B
368.00
17.38
N
Result that I'm getting from query:
price_source
volume
price
status
Source A
736.00
1.54
Y
Source B
368.00
17.05
N
db fiddle link of tables and query and results: https://dbfiddle.uk/?rdbms=postgres_14&fiddle=474b009c5cf5366961751a61c0f96c6c

Answer 1

I think you made a calculator error. I changed your fiddle to add a rolling sum and rolling average for the second part of your query. To get an average of .54 (Source A) your sum would need to be 12 less than the total of the values for this hour. 12 is the count of values for the hour so a possible slip in subtracting 12 before dividing by 12?
The other source (B) the total would need to be off by 4m (an addition of 4 to the sum). Not sure how this could have happened but ...
Anyway the fiddle is at https://dbfiddle.uk/?rdbms=postgres_14&fiddle=e65c38677f3ab92607bbff778bc0f69e