The relevant prior art is not the idea of a "map" or "reduce" function as such (that isn't what is significant about MR, anyway). The patent is about paralleli

The relevant prior art is not the idea of a "map" or "reduce" function as such (that isn't what is significant about MR, anyway). The patent is about parallelizing M and R operators for large-scale data analysis; I think that the relevant prior art would include 1980s work on parallel database systems (e.g. Gamma, Bubba).