Hello Aljoscha <aljos...@apache.org>, You mentioned: '.. Yes, this is right if you temperatures don’t have any other field on which you could partition them. '.
What I am failing to understand is that if temperatures are partitioned on some other field (in my use-case, I have one such: the temp_reading_timestamp), they will be pushed to different nodes (different threads in local run) based on that field. Because they will be computed (scattered) and later collected (gathered), how could I arrive at the _running_ average temperature? The client application needs to know *how the average temperature is changing over time'. Could you please fill in the gap in my understanding? -- Nirmalya -- Software Technologist http://www.linkedin.com/in/nirmalyasengupta "If you have built castles in the air, your work need not be lost. That is where they should be. Now put the foundation under them."