what does the text input format do?

770

Why Mapper runs in heavy weight process and not in a thread in MapReduce?

591

What is identity mapper and chain mapper?

624

How would you tackle calculating the number of unique visitors for each hour by mining a huge apache log? You can use post processing on the output of the mapreduce job.

770

What is the need of key-value pair to process the data in MapReduce?

617

Is reduce-only job possible in Hadoop MapReduce?

651

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

867

A number of combiners can be changed or not in MapReduce?

595

What is streaming?

624

How will you submit extra files or data ( like jars, static files, etc. ) For a mapreduce job during runtime?

619

Define Writable data types in MapReduce?

644

What is a "reducer" in Hadoop?

823

How to write a custom partitioner for a Hadoop MapReduce job?

601

What are the configuration parameters in the 'MapReduce' program?

631

What is a IdentityMapper and IdentityReducer in MapReduce ?

900