In case you have your own slow SQL query, you can optimize it automatically here.
For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:
CREATE INDEX b_idx_articleid ON B (ArticleId);
SELECT
C.[Date],
B.[GroupingA],
B.[GroupingB],
SUM(C.Sales) AS Sales
FROM
C
INNER JOIN
B
ON C.[ArticleId] = B.[ArticleId]
WHERE
B.Upload.Id = 1
GROUP BY
C.[Date],
B.[GroupingA],
B.[GroupingB]