[nl]

Rapidly growing, infrequently queried data is not the ideal scenario for most relational databases.

1) Relational databases typically aren't optimised for write-throughput. It's quite possible to do it, but you'll need fast and large disks (eg, FusionIO in a SAN or something).

2) Location-tracking applications typically don't require interactive queries - generally it is more a batch-based system that can be run offline.

Saying you are not going to be able to use a relational database is overstating it a bit in my view.

Clearly you can make it work, but something like Cassandra will give you better write thoughput, won't force you to rely on a SAN/NAS for data storage and will let you use Map/Reduce to batch process the data.