How to change a number of mappers running on a slave in MapReduce?

835

What is the relationship between Job and Task in Hadoop?

706

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

748

How many Reducers run for a MapReduce job?

740

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.

892

How does Hadoop Classpath plays a vital role in stopping or starting in Hadoop daemons?

746

What counter in Hadoop MapReduce?

693

In Hadoop what is InputSplit?

680

Mention what is the next step after mapper or maptask?

690

What happens if the quantity of the reducer is 0 in mapreduce?

637

How does inputsplit in mapreduce determines the record boundaries correctly?

681

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

720

Mention what are the main configuration parameters that user need to specify to run mapreduce job?

777

What are the main configuration parameters in a MapReduce program?

674

What are the the issues associated with the map and reduce slots based mechanism in mapReduce?

688