Aggregating tsrange values into day buckets with a tie-breaker - sql

Question

So I've got a schema that lets people donate $ to a set of organizations, and that donation is tied to a certain arbitrary period of time. I'm working on a report that looks at each day, and for each organization shows the total number of donations and the total cumulative value of those donations for that organization's day.
For example, here's a mockup of 3 donors, Alpha (orange), Bravo (green), and Charlie (Blue) donating to 2 different organizations (Foo and Bar) over various time periods:
I've created a SQLFiddle that implements the above example in a schema that somewhat reflects what I'm working with in reality: http://sqlfiddle.com/#!17/88969/1
(The schema is broken out into more tables than what you'd come up with given the problem statement to better reflect the real-life version I'm working with)
So far, the query that I've managed to put together looks like this:
WITH report_dates AS (
SELECT '2018-01-01'::date + g AS date
FROM generate_series(0, 14) g
), organizations AS (
SELECT id AS organization_id FROM users
WHERE type = 'Organization'
)
SELECT * FROM report_dates rd
CROSS JOIN organizations o
LEFT JOIN LATERAL (
SELECT
COALESCE(sum(doa.amount_cents), 0) AS total_donations_cents,
COALESCE(count(doa.*), 0) AS total_donors
FROM users
LEFT JOIN donor_organization_amounts doa ON doa.organization_id = users.id
LEFT JOIN donor_amounts da ON da.id = doa.donor_amounts_id
LEFT JOIN donor_schedules ds ON ds.donor_amounts_id = da.id
WHERE (users.id = o.organization_id) AND (ds.period && tsrange(rd.date::timestamp, rd.date::timestamp + INTERVAL '1 day', '[)'))
) o2 ON true;
With the results looking like this:
| date | organization_id | total_donations_cents | total_donors |
|------------|-----------------|-----------------------|--------------|
| 2018-01-01 | 1 | 0 | 0 |
| 2018-01-02 | 1 | 250 | 1 |
| 2018-01-03 | 1 | 250 | 1 |
| 2018-01-04 | 1 | 1750 | 3 |
| 2018-01-05 | 1 | 1750 | 3 |
| 2018-01-06 | 1 | 1750 | 3 |
| 2018-01-07 | 1 | 750 | 2 |
| 2018-01-08 | 1 | 850 | 2 |
| 2018-01-09 | 1 | 850 | 2 |
| 2018-01-10 | 1 | 500 | 1 |
| 2018-01-11 | 1 | 500 | 1 |
| 2018-01-12 | 1 | 500 | 1 |
| 2018-01-13 | 1 | 1500 | 2 |
| 2018-01-14 | 1 | 1000 | 1 |
| 2018-01-15 | 1 | 0 | 0 |
| 2018-01-01 | 2 | 0 | 0 |
| 2018-01-02 | 2 | 250 | 1 |
| 2018-01-03 | 2 | 250 | 1 |
| 2018-01-04 | 2 | 1750 | 2 |
| 2018-01-05 | 2 | 1750 | 2 |
| 2018-01-06 | 2 | 1750 | 2 |
| 2018-01-07 | 2 | 1750 | 2 |
| 2018-01-08 | 2 | 2000 | 2 |
| 2018-01-09 | 2 | 2000 | 2 |
| 2018-01-10 | 2 | 1500 | 1 |
| 2018-01-11 | 2 | 1500 | 1 |
| 2018-01-12 | 2 | 0 | 0 |
| 2018-01-13 | 2 | 1000 | 2 |
| 2018-01-14 | 2 | 500 | 1 |
| 2018-01-15 | 2 | 0 | 0 |
That's pretty close, however the problem with this query is that on days where a donation ends and that same donor begins a new one, it should only count that donor's donation one time, using the higher amount donation as a tie-breaker for the cumulative $ count. An example of that is on 2018-01-13 for organization Foo: total_donors should be 1 and total_donations_cents 1000.
I tried to implement a tie-breaker for using DISTINCT ON but I got off into the weeds... any help would be appreciated!
Also, should I be worried about the performance implications of my implementation so far, given the CTEs and the CROSS JOIN?

Answer 1

Figured it out using DISTINCT ON: http://sqlfiddle.com/#!17/88969/4
WITH report_dates AS (
SELECT '2018-01-01'::date + g AS date
FROM generate_series(0, 14) g
), organizations AS (
SELECT id AS organization_id FROM users
WHERE type = 'Organization'
), donors_by_date AS (
SELECT * FROM report_dates rd
CROSS JOIN organizations o
LEFT JOIN LATERAL (
SELECT DISTINCT ON (date, da.donor_id)
da.donor_id,
doa.id,
doa.donor_amounts_id,
doa.amount_cents
FROM users
LEFT JOIN donor_organization_amounts doa ON doa.organization_id = users.id
LEFT JOIN donor_amounts da ON da.id = doa.donor_amounts_id
LEFT JOIN donor_schedules ds ON ds.donor_amounts_id = da.id
WHERE (users.id = o.organization_id) AND (ds.period && tsrange(rd.date::timestamp, rd.date::timestamp + INTERVAL '1 day', '[)'))
ORDER BY date, da.donor_id, doa.amount_cents DESC
) foo ON true
)
SELECT
date,
organization_id,
COALESCE(SUM(amount_cents), 0) AS total_donations_cents,
COUNT(*) FILTER (WHERE donor_id IS NOT NULL) AS total_donors
FROM donors_by_date
GROUP BY date, organization_id
ORDER BY organization_id, date;
Result:
| date | organization_id | total_donations_cents | total_donors |
|------------|-----------------|-----------------------|--------------|
| 2018-01-01 | 1 | 0 | 0 |
| 2018-01-02 | 1 | 250 | 1 |
| 2018-01-03 | 1 | 250 | 1 |
| 2018-01-04 | 1 | 1750 | 3 |
| 2018-01-05 | 1 | 1750 | 3 |
| 2018-01-06 | 1 | 1750 | 3 |
| 2018-01-07 | 1 | 750 | 2 |
| 2018-01-08 | 1 | 850 | 2 |
| 2018-01-09 | 1 | 850 | 2 |
| 2018-01-10 | 1 | 500 | 1 |
| 2018-01-11 | 1 | 500 | 1 |
| 2018-01-12 | 1 | 500 | 1 |
| 2018-01-13 | 1 | 1000 | 1 |
| 2018-01-14 | 1 | 1000 | 1 |
| 2018-01-15 | 1 | 0 | 0 |
| 2018-01-01 | 2 | 0 | 0 |
| 2018-01-02 | 2 | 250 | 1 |
| 2018-01-03 | 2 | 250 | 1 |
| 2018-01-04 | 2 | 1750 | 2 |
| 2018-01-05 | 2 | 1750 | 2 |
| 2018-01-06 | 2 | 1750 | 2 |
| 2018-01-07 | 2 | 1750 | 2 |
| 2018-01-08 | 2 | 2000 | 2 |
| 2018-01-09 | 2 | 2000 | 2 |
| 2018-01-10 | 2 | 1500 | 1 |
| 2018-01-11 | 2 | 1500 | 1 |
| 2018-01-12 | 2 | 0 | 0 |
| 2018-01-13 | 2 | 1000 | 2 |
| 2018-01-14 | 2 | 500 | 1 |
| 2018-01-15 | 2 | 0 | 0 |