Join Dataset in stream

[eric hoffmann]

Hi.
I need to compute an euclidian distance between an input Vector and a full
dataset stored in Cassandra and keep the n lowest value. The Cassandra
dataset is evolving (mutable). I could do this on a batch job, but i will
have to triger it each time and the input are more like a slow stream, but
the computing need to be fast can i do this on a stream way? is there any
better solution ?
Thx