What is the use of combiner?

Combine Mapper output Separate Reducer output Separate Mapper input Separate Mapper output

According to a global survey by Jaspersoft, what is the most popular big data store?

Relational Databases Hadoop HDFS Analytic Databases MongoDB

What is the default namenode server port number?

50070 50020 50010 50040

Which ecosystem project is ideal for use when we have multiple mapreduce and pig programs to run in a sequence

Oozie Hive Pig Sqoop

What does JobTracker do

coordinates and schedules the job Stores blocks of data stores metadata acts as a mini reducer