Its not really about SQL or NoSQL - I believe AdRoll internally has systems that map SQL queries onto TrailDB where its needed.
Its about efficiency. TrailDB compresses the hell out of event streams grouped by some key (typically user). I think it's generally something like 100x - it does so by making certain assumptions about your data. Similarly, when operating on your event sequences, many of those operations can be performed as integer instructions on the compressed data.
TrailDB gives you order(s) of magnitude of leverage. That's the difference between doing analytics on a single machine and a cluster in many cases. There aren't too many other databases that were designed to gracefully handle tens of trillions of events, so its really not surprising that you need a different tool for that job.
Its about efficiency. TrailDB compresses the hell out of event streams grouped by some key (typically user). I think it's generally something like 100x - it does so by making certain assumptions about your data. Similarly, when operating on your event sequences, many of those operations can be performed as integer instructions on the compressed data.
TrailDB gives you order(s) of magnitude of leverage. That's the difference between doing analytics on a single machine and a cluster in many cases. There aren't too many other databases that were designed to gracefully handle tens of trillions of events, so its really not surprising that you need a different tool for that job.