If I take the index off the benchmark will run just about as fast for 500M rows as it did for 0 rows, at 500M rows MySQL's BTREE index starts to fall over, but

If I take the index off the benchmark will run just about as fast for 500M rows as it did for 0 rows, at 500M rows MySQL's BTREE index starts to fall over, but I have plenty of options to mitigate that. I don't think anything is a perfect fit for time series data, but again my point was that the traditional relational database's are _really_ good, and they do in fact scale up well beyond what most people think they will.