Hadoop MapReduce
Monday, March 01, 2010
3:03 PM
Hadoop MapReduce
A bit different than Google MapReduce
Five phases of a MapReduce query
put: put data on local disks
map: map keys in data to values; store on mapper. 
shuffle: sort ranges of map key output to reducers. 
reduce: store one result per unique key on disk. 
get: get results off disk. 