[rrd-developers] Re: Hallo!

Tobias Oetiker oetiker at ee.ethz.ch
Tue Jul 27 21:39:41 MEST 1999

Today you sent me mail regarding Re: Hallo! :

*> On Tuesday, July 27, Tobias Oetiker wrote:
*> > 
*> > uff ... great ... 
*> Again, thank you.  Now, two suggestions.  1 is easy to code (from the quick
*> peek I had), the other likely a little harder.
*> 1) Along with the current IF,GT,etc RPN notation, a DUP would be exceedingly
*> usefull.  Especially within cricket, where the data-source is implied in the
*> scale= portion.  Currently I could use that to remove "spikes" in the graph.
*> (My current RPN is: 'CDEF:sds1=ds1,8,*,ds1,8,*,10000000,LT,*', but within
*> cricket, all I can do is something like: 'scale=8,*', which is the tail end
*> of the CDEF.  If I had a DUP function, I could rewrite the above LT stuff...)

OK will be in 1.0.3 

*> 2) One more consolidation function.  However, this function could take an
*> argument to it, so I'm not sure how it would be invoked/etc.  The function
*> is something like 'WEIGHTED', which would be a weighted average, using some
*> sort of exponential, linear, or other function, to weigh the individual points
*> within the average.  One possibility, would be to have the ability to store
*> the weight of each point within the RRD file.  That way the "function" could
*> be hand crafted whichever way you wish it to be.  Common things like an expo-
*> nential, or linearly weighted function could be "built-in".
*> Something along the lines of:
*> RRA:WEIGHTED(linear,0):0.1:12:300		# Equivelant to 'AVERAGE'
*> RRA:WEIGHTED(linear,-1):0.1:12:300
*> RRA:WEIGHTED(exp,0.5):0.1:12:300
*> RRA:WEIGHTED(0.5,0.2,0.1,0.05,0.05,0.05,0.05):0.1:7:300
*> WEIGHTED(linear,X) -> X == slope

checkout rrd_format.h consolidation in this manner is not possible using the
current rrd_format ... it could be dine in rrd_graph or adding a new
data-source typoe called RRD which would use an existing RRD as datasource
for filling a new RRD ... 

*> I'm not sure if I'm making much sense here...
*> --Toby.

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