Returns the difference between the timestamps. This function will give the same result as timeval() => difference()
but is slightly faster.
Since all timestamps are in order, the difference will always be a positive value.
interval()
None
The returned series will contain the difference between timestamps as their values. The timestamp of the difference is the latest of the two compared timestamps.
# Select the interval between timestamps from 'series-001'
select interval() from 'series-001'