Question

I have a table with multiple products. For each product, I am collecting an history of prices. Thus I have four columns:

• log_entry
• product_id
• product_price
• timestamp

Until now, I updated all prices at the same time. This lead to an easy query: In a subquery, I filtered the max timestamp and then got all prices and products.

Today I changed my update policy: I now update prices for products asynchronously. This means, when I use my old query, I only get a product-price-pair with the maximum timestamp.

How do I get the most current price/the maximum timestamp for every product in one query?

Answer 1

You could use group by on a result that was sorted by timestamp. Not sure if it works:

select * from (
  select * from products 
    order by timestamp desc
) as products_temp
group by product_id;