I’d like some help on the below requirement. Suppose I’d like to know the number of metrics(count) I received from a set of hosts in the last 24 hours .
select count(*) from system where time > now() - 24h group by host
This query will not return a group for those hosts that have not sent data in the last 24 hours . I’d like to know how I could use something like fill() , so that I could return a count of 0 for those “host” which did not send any data in the last 24 hours.