[rrd-users] api for iterating over single rows in a rrd file

Daniel Pocock daniel at pocock.pro
Fri Jul 4 10:12:25 CEST 2014

On 04/07/14 09:57, Tobias Oetiker wrote:
> Hi Plamen,
> Yesterday Plamen Dimitrov wrote:
>> Hi rrdtool users!
>> As part of my google summer of code project with Ganglia I'm developing an
>> R package that imports the values from an RRD file into vectors in R
>> (without exporting to csv, xml or other intermediate format first). I'm
>> using the rrdfetch api to do this. Here is a working prototype:
>> https://github.com/pldimitrov/Rrd
>> Wnile this seems to work fairly well, it struck me that in a scenario when
>> I'm only interested in reading one row at a time (e.g. to compare values
>> from many RRDs simultaneously) , the rrdfetch code would need to go through
>> all error/sanity checks, find the RRA we want and seek to the desired
>> location in the file at each iteration.
>> I know the use of the internal rrd_read, rrd_seek, rrd_open, etc...
>> functions is not encouraged so I'm wondering what might be a good solution.
>> Ideally, it would be useful to have something that iterates one row at a
>> time, reads and caches the data.
>> Does anything like this already exist?  Would you agree it makes sense to
>> have this in addition to rrdfetch?
> no there is no iterator ... if you do see a memory problem with
> reading the whole file, you may want to split your reading into
> of say 10000 rows

Hi Tobi,

What do you think of the other half of the question, simultaneously
reading a row from all the RRDs?

Has anything like this been discussed before, has anybody else expressed
interest in that?



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