I've spoken to friends who've played with billion+ row Oracle RDBMS installs, and we (at Next Big Sound) have an offline snapshot MySQL instance with tables of up to about a hundred million rows (with over a hundred columns).

That said, I agree that distributed columnar stores end up being much more useful for large-scale analytics, and the power of high computation parallelism seals the deal. We've mostly moved on from those snapshot MySQL databases to Impala running on top of our Hadoop cluster, so you're preaching to the choir :)

That said, a hell of a lot of analytics can be done in a properly-structured SQL database, and schema changes aren't a big deal as long you don't need to do them online in a production system.

More info: http://stackoverflow.com/questions/14733462/can-mysql-handle...