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Derivative function not working?

Asked by Tobias Schlottke

Hi there,

I've got a little problem with the derivative function and can't get it to work so far:
I'm trying to plot the requests/min for an tomcat webserver.
So far, I've got the total number of requests in there, for example 400.000.000, each minute I get the new number.
As soon as I apply the derivative function, it just shows a scala from 0 to 1 and does not plot anything.
Am I getting this totally wrong?

Best,

Tobias

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Michael Leinartas (mleinartas) said : 		#1

Do you have gaps in the incoming metrics? The derivative function will return None for every pair of input values that has at least one None value in it. If that is the case, try first applying the keepLastValue() function to the data before applying the derivative function. Also look into nonNegativeDerivative which works better with counters that reset or roll over often.

You can inspect the values before and after applying the function(s) by copying a graph URL and appending &format=raw (or 'csv', or 'json'). This should give you a better idea of what's going on

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