[rrd-users] Re: disabling interpolation?

[Alex van den Bogaerdt]

Paul C. Williamson wrote:
> 
> Not to add fuel to the fire, but...
> 
> There were probably 5 people in the room from 9:00 am until 9:47, then 1 walked out leaving 4.  Over that hours, there were an average of 4.76 people in the room.
> 

Right.  As I said: don't mess with the averages.  However, it is safe
to say the minimum amount of people in that room is 4, not 4.76 and
the maximum amount of people in that room was 5, not 4.76 .
It makes no sense to say that during this interval there were 4.76
people in the room *unless* you are talking about averages.

This is why I think it is good to have a data source type which is
valid during the whole interval, independent of the time in this
interval that the data was entered.  See my other mail about this; it
makes it clear that the proposed "REAL" DST cannot be combined with
averages.

If you alter your example so that it talks about five minutes (and the
times can be 9:00 to 9:04 + 9:04 to 9:05) you have exactly the problem
that most people suffer from (assuming the default step time of 5 mins).

Either you measure at 9:00 and 9:05 *exactly* or you need another way to
work around the problem.  If I enter "4" for the number of people in the
room at 9:04, and the number used to be 5, I cannot say that there was
a minimum of 4.80 people in the room...

regards,
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