In the last post we saw how to run a MapReduce job on Hadoop. Now we're going to analyze how a MapReduce program works. And, if you don't know what MapReduce is, the short answer is "MapReduce is a programming model for processing large data sets wit…
This is a guide to migrating from Apache MapReduce 1 (MRv1) to the Next Generation MapReduce (MRv2 or YARN). See the following sections for more information: Introduction Terminology and Architecture For MapReduce Programmers: Writing and Running Job…
In the last post we saw how to write a MapReduce program for finding the top-n items of a dataset. The code in the mapper emits a pair key-value for every word found, passing the word as the key and 1 as the value. Since the book has roughly 38,000 w…
Python实现MapReduce 下面使用mapreduce模式实现了一个简单的统计日志中单词出现次数的程序: from functools import reduce from multiprocessing import Pool from collections import Counter def read_inputs(file): for line in file: line = line.strip() yield line.split() def count(file_name…
