Google introduced the MapReduce algorithm to perform massively parallel processing of very large data sets using clusters of commodity hardware. MapReduce is a core Google technology and key to maintaining Google's website indexes.
The general MapReduce concept is simple: The "map" step partitions the data and distributes it to worker processes, which may run on remote hosts. The outputs of the parallelized computations are "reduced" into a merged result. MapReduce works well when performing the sort of aggregate operations typical in business intelligence-daily sales totals for instance-as well as operations such as web search that involve searches through massive data sets.
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