Question

I store several properties of objects in hashsets. Among other things, something like “creation date”. There are several hashsets in the db.

So, my question is, how can I find all objects older than a week for example? Can you suggest an algorithm what faster than O(n) (naive implementation)?

Thanks,
Oles

Answer 1

My initial thought would be to store the data elsewhere, like relational database, or possibly using a zset.

If you had continuous data (meaning it was consistently set at N interval time periods), then you could store the hash key as the member and the date (as a int timestamp) as the value. Then you could do a zrank for a particular date, and use zrevrange to query from the first rank to the value you get from zrank.