Of course, you're right, but we didn't know that at the time. It turns out there's nothing we were doing that really warranted using a data warehouse (for that is what InfiniDB was really suited for). We were collecting a lot of numerical, time-series data, bulk loading it and then performing summarised queries periodically.

Mongo, Cassandra, etc are not good fits for this. Vertica was very expensive. In the end we went with a sharded and partitioned MySQL setup (partitioning really is great if you use it well). It's worked very well.