[feature request] Should support ceil and floor functions

[pauldix]

Some users want to round results from math and aggregates. These functions should act like transformation functions (like derivative). For example say you have a series where you're reporting uptime in seconds for devices and you want to show how many days it has been up.

-- ceil rounds up, floor rounds down
-- the first argument is the thing you're taking the ceiling of
-- this would give you as many data points as you have uptime reports, many of which
-- would be the same because of the large divisor
select ceil(value / 86400) from uptime where time > now() - 30d

-- if you're reporting uptime frequently, you may want to limit the number of points here
-- this would give you only 30 data points back
select ceil(last(value) / 86400) from uptime where time > now() - 30d group by time(1d) 

-- ceil and floor should support an optional second argument that specifies the precision to round to
select ceil(value / 86400, .2f) from uptime where time > now() - 30d

Just my initial thoughts on this. Feedback welcome.

[laf]

Thanks @pauldix

Exactly what we're looking for :)

[musl]

@pauldix Great idea. This will make some history graphs easier to make and read - especially for those targeted at an audience that's not expected to be well versed in statistics. I think it'll also help with clarity and style in other cases.

[toddboom]

Also adding a request for round() in response to #5435.

[beckettsean]

As mentioned in my post to the mailing list we are experimenting with simplifying our open GitHub Issues. This feature request has been rolled into an aggregate issue for all function requests, so that we can close this issue until we are ready to work on it.

You may continue to make comments here. Closing the issue does not mean we are rejecting this idea.

[MikiDi]

Hi,
I would like to have a go at implementing the CEIL() and FLOOR() functions.
However, I'm new to the project ... could anyone give some pointers on what to look at first, which special cases to consider, etc? :-)

Michaël

[timhallinflux]

closed via #9632