reserved. Integration with MySQL Reducing Reduce(key, list) sum the list Output(key, sum) Hadoop aggregates the keys and calls reduce for each unique key: <word1>, (1,1,1,1,1,1…1) <word2>, (1,1,1) <word3>, (1,1,1,1,1,1) . Final result: <word1>, 45823 <word2>, 1204 <word3>, 2693