When the reducers are are started in a mapreduce job?

593

What is the sequence of execution of map, reduce, recordreader, split, combiner, partitioner?

699

Can MapReduce program be written in any language other than Java?

927

What is partitioner and its usage?

688

How do Hadoop MapReduce works?

720

Is it legal to set the number of reducer task to zero? Where the output will be stored in this case?

660

In Map Reduce why map write output to Local Disk instead of HDFS?

902

What is Shuffling and Sorting in a MapReduce?

659

How to submit extra files(jars,static files) for MapReduce job during runtime in Hadoop?

769

Explain the sequence of execution of all the components of MapReduce like a map, reduce, recordReader, split, combiner, partitioner, sort, shuffle.

649

How many Reducers run for a MapReduce job?

688

What is Hadoop Map Reduce ?

804

How to create a custom key and custom value in MapReduce Job?

674

What is the data storage component used by Hadoop?

619

Why MapReduce uses the key-value pair to process the data?

632