New question #184877 on Graphite:
https://answers.launchpad.net/graphite/+question/184877

Hi, 

I know this problem has been asked previously but I can't find a good solution. 
The problem is that the derivative function simply calculates the difference 
between two metrics without taking into account the timestamp, so, if you 
sample at a n-minutes pace, the derivative will show values grouped into that 
sampling rate (normally that imply bigger values). A solution could be to scale 
the result. This is alright as long as you know the sampling rate, Im currently 
managing thousand of metrics and the graph creation is automated by means of 
munin2graphite so this approarch won't work. Another approach would be that of 
summarizing (i.e. oversampling) the metric before derivation, but this does not 
work, the result is not equivalent to that of the scaling method. 

Looking into the code, I see, that the TimeSeries has a property called step 
that I guess is the time difference between points. Wouldn't it be correct to 
create a new funcion (let's call it timeUnitDerivative), that divide the 
function increment by the step in the implementation?  If so I can myself send 
a patch with docu.

Thanks in advance, Jose Fernandez (magec)

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