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

Simon Hobson linux at thehobsons.co.uk
Fri Jul 4 12:19:20 CEST 2014

Daniel Pocock <daniel at pocock.pro> wrote:

>> From a technical perspective, if rrdtool provided such an API:
> - it would make programming easier for people accessing data in this way
> - it could be optimized for efficiency (e.g. the IO subsystem would be
> reading 4KiB of data from each file at a time, the iterator would then
> return values from that buffer and the IO subsystem would only do more
> reads when the iterator advances over a page boundary)
>> From a user perspective, it would enable people to look across all their
> RRDs, e.g. to answer questions like "which CPUs were over 90% utilized
> at any time between 09:00 and 10:00"

I can see the point of being able to iterate through the data (open, seek, get row, get row, ...) - I'm sure there are probably a few applications where that would be useful.

I don't see where having RRD handle multiple files would be any better than the program itself opening multiple files. I suspect it would be a massively complicated task to build generic "open and merge multiple files" function given the variety of ways they can be configured.
Better, IMO, for your program to handle that - you are in a position to know what RRDs you've set up, and overall it's probably no harder than finding a reliable way to tell RRD what you want.

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