>>Reservoir sampling is appropriate with more than just a set of unknown size -- you very frequently know the size of a set, but it's still too big to sample di

>>Reservoir sampling is appropriate with more than just a set of unknown size -- you very frequently know the size of a set, but it's still too big to sample directly. I'm not sure that I buy this...Do you have an example? Still, it is a neat algorithm. And it is a true stream query algorithm, that is, if you have an open-ended stream, it maintains a random sample at all times.