Google has received a patent for the technique known as MapReduce. The patent, number 7,650,331 applied for in 2004, is entitled "System and method for efficient large-scale data processing" and covers the process of mapping work to multiple processors and then reducing the intermediate results from these processors to a final result. The technique is used widely by data mining companies, for example, in Yahoo's search infrastructure, Amazon's Elastic MapReduce service and IBM's M2 platform. The Apache Hadoop project is the most prominent open source implementation of the technique.

The concept of mapping and reducing fuctions has been a fundamental idea behind distributed parallel processing for many years, and in a dispute it could be reasonably claimed that Google didn't invent MapReduce itself, but that would just move the argument on to the specific claims within the patent.

Google has told US media that "Like other responsible, innovative companies, Google files patent applications on a variety of technologies it develops. While we do not comment about the use of this, or any part of our portfolio, we feel that our behaviour to date has been in line with our corporate values and priorities". Given that Google has not pursued patent infringements and appear to have been building a defensive patent portfolio, it is believed by some that Google are ensuring that it is not possible for a patent troll to obtain a similar patent and use it against Google and others.

(djwm)