Oracle partition with Monthly Interval - sql

Question

I am performing a query with a partition window of 1 calendar month. The data I'm working with is collected at regular intervals eg. every fifteen minutes.
Here is the code:
SELECT AVG(data_value) OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN INTERVAL '1' MONTH PRECEDING AND CURRENT ROW)
This query works well, and collects the monthly average. The only problem is that the start and end of the interval are exactly a month apart, so the boundaries of the interval window are inclusive, eg. the start would be Nov-01-2019 00:00 and the End would be Dec-01-2019 00:00.
I need to make it so that the starting boundary is not included, because it's not considered part of the data set, eg. Start at Nov-01-2019 00:15 (the next row) and the End would still be Dec-01-2019 00:00.
I'm wondering if there's something that Oracle can do that would achieve this.
I imagine the code looking something like this:
SELECT AVG(data_value) OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN INTERVAL '1' MONTH (+ 1 ROW) PRECEDING AND CURRENT ROW)
I've tried several variants of this but Oracle does not like them. Any help would be appreciated.

Answer 1

Work out how many days there were in the previous month using:
EXTRACT( DAY FROM TRUNC( time_stamp, 'MM' ) - 1 )
The use the NUMTODSINTERVAL function to create an interval of one fewer days so you exclude the extra day that is being counted:
SELECT id,
data_value,
time_stamp,
AVG(data_value)
OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN NUMTODSINTERVAL(
EXTRACT( DAY FROM TRUNC( time_stamp, 'MM' ) - 2 ),
'DAY'
) PRECEDING
AND CURRENT ROW
) AS avg_value_month_minus_1_day
FROM table_name;
So, if your data is:
CREATE TABLE table_name ( id, data_value, time_stamp ) AS
SELECT 1,
LEVEL,
DATE '2020-01-01' + LEVEL - 1
FROM DUAL
CONNECT BY LEVEL <= 50;
Then comparing the above query to your output with:
SELECT id,
data_value,
time_stamp,
AVG(data_value)
OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN NUMTODSINTERVAL(
EXTRACT( DAY FROM TRUNC( time_stamp, 'MM' ) - 2 ),
'DAY'
) PRECEDING
AND CURRENT ROW
) AS avg_value_month_minus_1_day,
AVG(data_value)
OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN INTERVAL '1' MONTH PRECEDING
AND CURRENT ROW
) AS avg_value_month
FROM table_name;
Outputs (for February, when there is a full month of preceding data):
ID | DATA_VALUE | TIME_STAMP | AVG_VALUE_MONTH_MINUS_1_DAY | AVG_VALUE_MONTH
-: | ---------: | :------------------ | --------------------------: | --------------:
1 | 32 | 2020-02-01 00:00:00 | 17 | 16.5
1 | 33 | 2020-02-02 00:00:00 | 18 | 17.5
1 | 34 | 2020-02-03 00:00:00 | 19 | 18.5
1 | 35 | 2020-02-04 00:00:00 | 20 | 19.5
1 | 36 | 2020-02-05 00:00:00 | 21 | 20.5
1 | 37 | 2020-02-06 00:00:00 | 22 | 21.5
1 | 38 | 2020-02-07 00:00:00 | 23 | 22.5
1 | 39 | 2020-02-08 00:00:00 | 24 | 23.5
1 | 40 | 2020-02-09 00:00:00 | 25 | 24.5
1 | 41 | 2020-02-10 00:00:00 | 26 | 25.5
1 | 42 | 2020-02-11 00:00:00 | 27 | 26.5
1 | 43 | 2020-02-12 00:00:00 | 28 | 27.5
1 | 44 | 2020-02-13 00:00:00 | 29 | 28.5
1 | 45 | 2020-02-14 00:00:00 | 30 | 29.5
1 | 46 | 2020-02-15 00:00:00 | 31 | 30.5
1 | 47 | 2020-02-16 00:00:00 | 32 | 31.5
1 | 48 | 2020-02-17 00:00:00 | 33 | 32.5
1 | 49 | 2020-02-18 00:00:00 | 34 | 33.5
1 | 50 | 2020-02-19 00:00:00 | 35 | 34.5
db<>fiddle here

Answer 2

Alas, Oracle doesn't support intervals with both months and smaller units.
One method is to subtract it out:
select (sum(data_value) over (partition by id
order by time_stamp
range between interval '3' month preceding and current row
) -
sum(data_value) over (partition by id
order by time_stamp
range between interval '3' month preceding and '3' month preceding
)
) /
(count(data_value) over (partition by id
order by time_stamp
range between interval '3' month preceding and current row
) -
count(data_value) over (partition by id
order by time_stamp
range between interval '3' month preceding and '3' month preceding
)
)
Admittedly, this is cumbersome for an average, but it might be just fine for a sum() or count().

Answer 3

To shift the window of time that you are looking at you can shift the value you are sorting on by an appropriate interval of time:
SELECT AVG(data_value)
OVER (PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN INTERVAL '1' MONTH PRECEDING AND CURRENT ROW
) Current_Calc
, AVG(data_value)
OVER (PARTITION BY id
ORDER BY time_stamp - interval '15' minute
RANGE BETWEEN INTERVAL '1' MONTH PRECEDING AND CURRENT ROW
) Shift_Back
, AVG(data_value)
OVER (PARTITION BY id
ORDER BY time_stamp + interval '15' minute
RANGE BETWEEN INTERVAL '1' MONTH PRECEDING AND CURRENT ROW
) shift_forward
FROM Your_Data
based on the description of your problem I believe you want to shift it back by 15 minutes, but I could be misreading the problem statement, and without appropriate data to test against, and expected results </shrugs>
These are sliding windows that always contain one months worth of data relative to the current time_stamp This means that for each time_stamp month you will get anywhere from 29 to 32 days worth of data with some of that data being counted in both the current and preceding months averages.
On the other hand, if what you are interested in is averages for the discreet months, then you should be partitioning by month rather creating a sliding window, if you want running averages per month you can add the sort, but you won't need the windowing clause:
SELECT TRUNC(time_stamp, 'MM') MON
, AVG(data_value)
OVER (PARTITION BY id, TRUNC(time_stamp, 'MM')) MON_AVG
, AVG(data_value)
OVER (PARTITION BY id, TRUNC(time_stamp, 'MM')
ORDER BY time_stamp) RUN_MON_AVG
, TRUNC(time_stamp - INTERVAL '15' MINUTE, 'MM') MON_2
, AVG(data_value)
OVER (PARTITION BY id, TRUNC(time_stamp - INTERVAL '15' MINUTE, 'MM')
) MON_AVG_2
, AVG(data_value)
OVER (PARTITION BY id, TRUNC(time_stamp - INTERVAL '15' MINUTE, 'MM')
ORDER BY time_stamp) RUN_MON_AVG
FROM Your_Data

Answer 4

Thanks for the feedback! I was able to assemble the answer I needed based on the answers above. Here is the code that I went with:
SELECT AVG(data_value) OVER (
PARTITION BY id
ORDER BY time_stamp
RANGE BETWEEN (NUMTODSINTERVAL(EXTRACT( DAY FROM (TRUNC(time_stamp,'MM') - 1) ),'DAY') - NUMTODSINTERVAL(1,'SECOND')) PRECEDING AND CURRENT ROW)
Because my interval is exactly one month, and I want to remove the first entry, I first convert the previous month into an interval in seconds, as recommended above. Then I subtract one second from the lower bound of the interval. This has the effect of making the lower bound of the interval an "open" bound and the upper bound a "closed" bound.
As a side note, I used one second because the periodicity of my dataset is not consistent, but its minimum is three minutes, so anything less than that will work.