Precalculate numbers of records for each possible combination - mysql

Question

I have a mySQL database table containing cellphones information like this:
ID Brand Model Price Type Size
==== ===== ===== ===== ====== ====
1 Apple A71 3128 A 40
2 Samsung B7C 3128 B 20
3 Apple ZX5 3128 A 30
4 Huawei Q32 2574 B 40
5 Apple A21 2574 A 25
6 Apple A71 3369 A 30
7 Samsung A71 7413 C 40
Now I want to create another table, that would contain counts for every possible combination of the parameters.
Params Count
============================================== =======
ALL 1000000
Brand(Apple) 20000
Brand(Apple,Samsung) 40000
Brand(Apple),Model(A71) 7100
Brand(Apple),Type(A) 6000
Brand(Apple),Model(A71,B7C),Type(A,B) 7
Model(A71) 12514
Model(A71,B7C) 26584
Model(A71),Type(A) 6521
Model(A71),Type(A,B) 8958
Model(A71),Type(A,B),Size(40) 85
And so on for every possible combination. I was thinking about creating a stored procedure (that i would execute periodically), that would perform queries with every existing condition like that, but I am a little stuck on how exactly should it look like. Or is there a better way how to do this?
Edit: the reason why I want to store information like this is to be able to show number of results in filter in client application, like in the picture.
I would like to create index on the Params column to be able to get the Count number for given hash instantly, improving performance.
I also tried querying and caching the values dynamically, but I want to try this approach as well, so I can compare which one is more effective.
This is how I am calculating the counts now:
SELECT COUNT(*) FROM products;
SELECT COUNT(*) FROM products WHERE Brand IN ('Apple');
SELECT COUNT(*) FROM products WHERE Brand IN ('Apple', 'Samsung');
SELECT COUNT(*) FROM products WHERE Brand IN ('Apple') AND Model IN ('A71');
etc.

Answer 1

You can use a ROLLUP for this.
SELECT
model, type, size, COUNT(*)
FROM mytab
GROUP BY 1, 2, 3
WITH ROLLUP
With your sample data, we get the following:
| model | type | size | COUNT(*) |
| ----- | ---- | ---- | -------- |
| A21 | A | 25 | 1 |
| A21 | A | | 1 |
| A21 | | | 1 |
| A71 | A | 30 | 1 |
| A71 | A | 40 | 1 |
| A71 | A | | 2 |
| A71 | C | 40 | 1 |
| A71 | C | | 1 |
| A71 | | | 3 |
| B7C | B | 20 | 1 |
| B7C | B | | 1 |
| B7C | | | 1 |
| Q32 | B | 40 | 1 |
| Q32 | B | | 1 |
| Q32 | | | 1 |
| ZX5 | A | 30 | 1 |
| ZX5 | A | | 1 |
| ZX5 | | | 1 |
| | | | 7 |
The subtotals are present in the rows with null values in different columns, and the total is the last row where all group by columns are null.