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Well, he's absolutely right. MapReduce apparently didn't last that long at Google — it's long been supplanted by other technologies internally.

But MapReduce has long been superseded by Spark outside of Google right?

Which ones?

As far as I remember, mostly Flume (open sourced as Apache Beam and also known as Cloud Dataflow on GCP).

Flume/Beam still provides map/reduce as operations, mind you, but with a much richer processing model.