So, if I have an event like "program observed a car at 2017-04-20 15:15:15.9939311", and I want to calculate summary statistics over time for that -- select cou

So, if I have an event like "program observed a car at 2017-04-20 15:15:15.9939311", and I want to calculate summary statistics over time for that -- select count(*) where car_time % 86400 == foo". That's the one kind of query I've been finding problematic in Prometheus. (Edited to add: This was answered by another reply -- Prometheus has to do a full table scan for things like this.)