[vz-dev] Why do you not use RRD?

justin at justinotherguy.org justin at justinotherguy.org
Fri Dec 19 23:21:07 CET 2014


> Am 18.12.2014 um 20:42 schrieb Ralf G. R. Bergs <Ralf+VolksZaehler at bergs.biz>:
> That reminded me about something that I wanted to ask from the very
> beginning: Why do you not use RRD in the middleware?

funny thing is:
this question has been asked (and answered!) a number of times before; it definitely is a legit question.

The advantages of RRD (lower resource requirements, maximum file size, …) have been clear from the start. There has always been one major drawback:
looking at the DIN rail meters you realize that the number of pulses / entries in your db is not constant over time, but proportional to the electric power.
Mapping that to a db that is strictly made for data that comes in at a constant rate gives you less precise results the lower the number of entries (= pulses) per time is.
In short: for the DIN rail meters RRD has always been a very bad choice.

Looking at the EDL meters you do not have this effect. I can’t remember someone asking the question ever since the EDL meters have taken „center stage“ in the project.
So: thanks for bringing that idea up again :-)

I would think this could be a very good idea - well worth a try, anyway!

Doctrine doesn’t seem to support RRD (I know - omitting doctrine would help save even more resources, but I see a common code base as a big advantage), so I reckon the middleware would need to speak to RRD natively.

Should be an interesting development. Care to give it a try?

Regards, J.

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