How to optimize group by and where

[Eric Colson]

Hi everybody,

I try since several days to improve the speed of the following query:
SELECT id_magasin, id_produit, SUM(int_qte_vendue)
FROM dwh.etl_vente
WHERE int_date BETWEEN 1148 AND 1178
AND id_magasin IN (6, 2, 9, 5, 31)
GROUP BY 1, 2;

I run the optimizer and I can read in the extra column:
Using temporary
Using Filesort

I have add a unique index on the three columns:
alter table etl_vente ADD UNIQUE NDX_MAGASIN4 (int_date, id_magasin, id_produit);

However, the "using temporary, using filesort" result always appears when running the optimizer.

What is wrong? Can someone help me please?

Eric