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

Tobias Oetiker tobi at oetiker.ch
Fri Jul 4 09:57:24 CEST 2014

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


> Regards,
> Plamen

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
www.oetiker.ch tobi at oetiker.ch +41 62 775 9902

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