[tracker1]

I think it depends partly on implementation and partly on their use case... The way ES works probably doesn't do well past a couple hundred nodes, max and even then likely has some real issues. Though they could have several independent clusters and shard out their users. What it looks like they implemented will scale better (to thousands of servers), and probably work better with their design.

That said, I'm somewhat surprised they didn't just try doing custom index/word counters against a larger cassandra cluster, which would scale well while still being somewhat out of the box as a software approach. I didn't thoroughly read through the article, but not sure of their use of stemming/mapping for word bases either.