How to set the number of mappers for a MapReduce job?

687

Explain the Reducer's reduce phase?

1054

How many Mappers run for a MapReduce job?

609

When should you use a reducer?

630

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

650

List the network requirements for using Hadoop ?

627

What happen if the number of the reducer is 0 in MapReduce?

652

what happens when Hadoop spawned 50 tasks for a job and one of the task failed?

691

What do you understand by the term Straggler ?

686

In Hadoop, which file controls reporting in Hadoop?

774

Define Writable data types in MapReduce?

675

If reducers do not start before all mappers finish then why does the progress on mapreduce job shows something like map(50%) reduce(10%)? Why reducers progress percentage is displayed when mapper is not finished yet?

712

Is there any point of learning mapreduce, then?

646

What do you understand by compute and storage nodes?

681

How can you add the arbitrary key-value pairs in your mapper?

1423