Is it possible to reset *view.Data on each call to ExportView

[Jack L]

Hi,

I'm writing an exporter in Go and am attempting to implement the function ExportView(vd *view.Data).  I'm exporting to a system that does not understand cumulative counters.  I need to send the delta of values, not the total value, each time.  I've noticed that each time ExportView is called for a view setup with view.Count() or view.Sum(), I'm getting the cumulative values.  Is it possible to just get the delta?

I could remember and send deltas easily enough, but things get much more tricky with view.Distribution. For this, I would also want the distribution of values between calls to ExportView but I appear to get the total distribution.  Is there a way to get just the distribution between calls?

Thanks!

[Morgan McLean]

+ Rahul

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[Rahul Patel]

Hi Jack,

It is not possible to get delta from the library. You would need to do something like metric-adjuster used for scraping prometheus. In a nut-shell metric-adjuster caches the first value and then subtracts the first value from any subsequent value. This is slightly different from what you want. You need to delta compare to previous. With slight modification you should be able to use it.

BTW, you should use ExportMetrics api instead of ExportView.

-Rahul

[Jack L]

Thanks!   I was following the documentation on https://opencensus.io/exporters/custom-exporter/go/metrics/ which uses     ExportView(vd *view.Data).  Why should I use ExportMetrics instead?

[Rahul Patel]

Metrics is new (better) representation of aggregated data. ExportMetrics API uses this new format. ExportView will be deprecated. 

Also, currently we are working on Open-Telemetry (merge of OpenCensus and OpenTracing). In OpenTelemetry export api will be aligned to ExportMetrics.

-Rahul

[Eric Shen]

Hi Rahul, 

I am using OpenCensus Java client lib and Prometheus exporter. I noticed the same issue. This thread is almost 2 yrs old. I am wondering if OpenCensus now supports delta out of box? Or I still write my own metric-adjuster? 

Thanks, 

Eric