Top 10 products for dates between - clickhouse

Question

I'm trying to figure out the better way of creating a single query that will produce a result with top 10 products for each date. I have a row with two columns - PID (int) and EventDate (date), a row for each click.
Can you suggest how I can get the result with Top 10 products clicked on for a date range? I'm getting stuck on understanding how the sub-query must be constructed. I can only get the part with group by date, but then my mind gets stuck on count() and aggregation issues.
Here's my query for an individual date, but I want to have to for a range of dates. I can, of course, do sub-query by generating event dates, but want to figure out how to do it more elegantly.
SELECT TOP 10 COUNT() as count, PID
FROM view_product
WHERE EventDate = toDate('2020-05-11')
GROUP BY PID
ORDER BY count DESC
The expected output is something like this:
PID Count Date
1 123 2020-02-04
21 101 2020-02-04
1332 99 2020-02-04
11 51 2020-02-04
634 49 2020-02-04
1332 43 2020-02-04
1 24 2020-02-04
21 23 2020-02-04
1332 6 2020-02-04
11 3 2020-02-04
1 266 2020-02-02
21 241 2020-02-02
1332 232 2020-02-02
11 179 2020-02-02
634 163 2020-02-02
1332 159 2020-02-02
1 144 2020-02-02
21 100 2020-02-02
1332 99 2020-02-02
11 74 2020-02-02

Answer 1

It needs to use LIMIT BY-clause that takes 10 top rows of each day:
SELECT
PID,
EventDate,
count() AS Count
FROM view_product
WHERE EventDate >= '2020-05-01' AND EventDate < '2020-06-01'
GROUP BY EventDate, PID
ORDER BY EventDate, Count DESC
LIMIT 10 BY EventDate;
The test example:
SELECT
PID,
EventDate,
count() AS Count
FROM (
/* emulate test set */
SELECT test_data.1 AS PID, toDate(test_data.2) AS EventDate
FROM (
SELECT arrayJoin([
(1, '2020-02-04'),
(21, '2020-02-04'),
(1332, '2020-02-04'),
(11, '2020-02-04'),
(634, '2020-02-04'),
(1, '2020-02-04'),
(1, '2020-02-04'),
(21, '2020-02-04'),
(1, '2020-02-04'),
(1, '2020-02-02'),
(21, '2020-02-02'),
(11, '2020-02-02'),
(1332, '2020-02-02'),
(1332, '2020-02-02'),
(1332, '2020-02-02'),
(11, '2020-02-02')]) test_data))
GROUP BY EventDate, PID
ORDER BY EventDate, Count DESC
LIMIT 2 BY EventDate;
/* result
┌──PID─┬──EventDate─┬─Count─┐
│ 1332 │ 2020-02-02 │ 3 │
│ 11 │ 2020-02-02 │ 2 │
│ 1 │ 2020-02-04 │ 4 │
│ 21 │ 2020-02-04 │ 2 │
└──────┴────────────┴───────┘
*/
To get just n-top items without count-values use topK-aggregated function:
SELECT
EventDate,
topK(10)(PID)
FROM (
/* emulate test set */
SELECT test_data.1 AS PID, toDate(test_data.2) AS EventDate
FROM (
SELECT arrayJoin([
(1, '2020-02-04'),
(21, '2020-02-04'),
(1332, '2020-02-04'),
(11, '2020-02-04'),
(634, '2020-02-04'),
(1, '2020-02-04'),
(1, '2020-02-04'),
(21, '2020-02-04'),
(1, '2020-02-04'),
(1, '2020-02-02'),
(21, '2020-02-02'),
(11, '2020-02-02'),
(1332, '2020-02-02'),
(1332, '2020-02-02'),
(1332, '2020-02-02'),
(11, '2020-02-02')]) test_data))
GROUP BY EventDate;
/* result
┌──EventDate─┬─topK(10)(PID)──────┐
│ 2020-02-02 │ [1332,11,1,21] │
│ 2020-02-04 │ [1,21,1332,11,634] │
└────────────┴────────────────────┘
*/