Re: Using a windowed counter

"Alex van den Bogaerdt" <[email protected]> Wed, 14 Jun 2017 01:07:31 +0200

Newsgroups	gmane.comp.db.rrdtool.user
Message-ID	<dc1bb34748603e81961124763b2d52b7.squirrel@webmail.argewebhosting.nl>

> 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.