[rrd-users] RRDtool spread values by time on rrd, how to turn off this behavior?

[Simon Hobson]

Daniel Hilst wrote:

what must be the most frequently asked question on this list

>2) The feed it with:
>rrdtool update test.rrd 1334578211:10
>rrdtool update test.rrd 1334578221:0
>
>
>I get
>1334578210 9.000000
>1334578220 1.000000

Terse answer: This is normal behaviour, it is **EXACTLY** how RRD is 
intended to work, and no you can't turn it off.

Garrulous answer:
RRD is designed to do one thing well, normalise and store data at 
specified resolutions, in an economic way. It is not a general 
purpose database - if you want to store arbitrary data for arbitrary 
times and get the original data out then you should use a regular 
database.
**ALL** data is normalised and consolidated according to the 
parameters used when creating the database. With some care* it is 
possible to make the normalisation a null operation, and using a 
consolidation process of one data point consolidated into one 
consolidated data point will make the consolidation a null operation 
as well - but both processes are still performed.

Alex has an excellent set of tutorials at
http://www.vandenbogaerdt.nl/rrdtool/
In particular, see "Rates, normalizing and consolidating"

* To make normalisation a null operation, you must supply data values 
every step time, and they must be timestamped **exactly** on the step 
time boundary. These boundaries are always an integer multiple of 
step time since unix epoch (midnight, Jan 1, 1970 UTC) and this 
cannot be changed.
-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.