[rrd-users] Using a windowed counter

Alex van den Bogaerdt alex at vandenbogaerdt.nl
Wed Jun 14 01:07:31 CEST 2017

> A far simpler solution is; it's just a counter that resets every hour.

No it's not.

>> > 011111244445678888889998767777765555553444335888889899987677
>> > 010000120001121000121000012000110000010100012300011010001210

Look approximately halfway:  98767
Then look below: 00012

The "counter" goes from 7 to 6, as a result of rainfall 1 being added and
2 being removed from the window.

If you treat this as a counter being reset every hour, you would get
negative rainfall, or counter overflow with the resulting huge flood, or
rates becoming unknown because of sanity checks.

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