What is the purpose of shuffling and sorting phase in the reducer in Map Reduce Programming?

What is the purpose of shuffling and sorting phase in the reducer in Map Reduce Programming?

sorting hadoop mapreduce hdfs shuffle

hadoop

Chaining multiple MapReduce jobs in Hadoop

hadoop mapreduce

hadoop

How does Hadoop process records split across block boundaries?

hadoop split mapreduce block hdfs

hadoop

How does the MapReduce sort algorithm work?

algorithm sorting parallel-processing hadoop mapreduce

hadoop

Can apache spark run without hadoop?

hadoop amazon-s3 apache-spark mapreduce mesos

hadoop

Is there a .NET equivalent to Apache Hadoop? [closed]

c# .net hadoop mapreduce

hadoop

When do reduce tasks start in Hadoop?

hadoop mapreduce reduce

hadoop

Container is running beyond memory limits

hadoop mapreduce hadoop-yarn mrv2

hadoop

Hadoop truncated/inconsistent counter name

java hadoop mapreduce hadoop-yarn

hadoop

merge output files after reduce phase

hadoop mapreduce

hadoop

What is Hive: Return Code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask

hadoop mapreduce hive

hadoop

Integration testing Hive jobs

java testing hadoop mapreduce hive

hadoop

Where does hadoop mapreduce framework send my System.out.print() statements ? (stdout)

hadoop mapreduce

hadoop

data block size in HDFS, why 64MB?

database hadoop mapreduce block hdfs

hadoop

hadoop.mapred vs hadoop.mapreduce?

apache hadoop mapreduce

hadoop