问题
I have table products:
+----------+-----------+----------+---------+
|family_id |shopper_id |product_id|quantity |
+----------+-----------+----------+---------+
|A |1 |Kit Kat |10 |
|A |1 |Kit Kat |5 |
|A |1 |Snickers |9 |
|A |2 |Kit Kat |7 |
|B |3 |Kit Kat |2 |
+----------+---------- +----------+---------+
For each product, I want to calculate 2 totals:
- total quantity per shopper
- total quantity per family. Sum of total quantities for all shoppers in the same family.
The final table should look like:
+----------+----------+-------------------------+-----------------------+
|shopper_id|product_id|total_quantity_shopper |total_quantity_family |
+----------+----------+-------------------------+-----------------------+
|1 |Kit Kat | 15 | 22 |
|1 |Snickers | 9 | 9 |
|2 |Kit Kat | 7 | 22 |
|3 |Kit Kat | 2 | 2 |
+----------+----------+-------------------------|-----------------------|
This is my query:
SELECT
distinct shopper_id,
product_id,
sum(quantity) OVER (PARTITION BY shopper_id, product_id) as total_quantity_shopper,
sum(quantity) OVER (PARTITION BY family_id, product_id) as total_quantity_family
FROM
products;
But looking at the query plan, it looks very inefficient (I think). How can I improve the query above?
回答1:
I think the family is a hierarchy for the shopper. So, I would suggest group by and window functions:
select family_id, shopper_id, product_id,
sum(quantity) as total_quantity_shopper,
sum(sum(quantity)) over (partition by family_id, product_id) as total_quantity_family
from products
group by family_id, shopper_id, product_id
来源：https://stackoverflow.com/questions/64687823/optimizing-query-with-multiple-sums