Analysis of information sources in references of the Wikipedia article "MapReduce" in English language version.
As of October, Google was running about 3,000 computing jobs per day through MapReduce, representing thousands of machine-days, according to a presentation by Dean. Among other things, these batch routines analyze the latest Web pages and update Google's indexes.
"We don't really use MapReduce anymore" [Urs Hölzle, senior vice president of technical infrastructure at Google]
The MapReduce implementation in MongoDB has little to do with map reduce apparently. Because for all I read, it is single-threaded, while map-reduce is meant to be used highly parallel on a cluster. ... MongoDB MapReduce is single threaded on a single server...