Yeah, there's a big difference between something that's pure distributed tracing (this) and something that does metrics/monitoring as well (TraceView, New Relic

Yeah, there's a big difference between something that's pure distributed tracing (this) and something that does metrics/monitoring as well (TraceView, New Relic, ...). Sampling is a valid way to make distributed tracing scalable and performant, but it can also limit the use-cases for the data. I imagine this being used for episodic debug cases, where one could turn up the sample rate and pay only for the traces captured/queried during an incident. But you would need to do your monitoring and trending separately. I wouldn't be surprised if they eventually start integrating this better with CloudWatch for that reason, though it doesn't seem to be doing any of that today. Disclosure: I work on TraceView (traceview.solarwinds.com) which is distributed tracing based APM product. We're inspired by Google Dapper and x-trace, both mentioned elsewhere in this thread.