What is HADOOP?
Hadoop is an open-source software framework. Hadoop was created by Doug Cutting and Mike Cafarella in 2005. Cutting, who...
Category: Interview Question
What is DataNode in hadoop?
A DataNode in hadoop stores data in the [Hadoop File System]. A functional file system has more than one...
What is NameNode in hadoop?
The NameNode in hadoop is the centerpiece of an HDFS file system. It keeps the directory tree of all...
What is JobTracker and TaskTracker in hadoop?
The main work of JobTracker and TaskTracker in hadoop is given below. JobTracker is a master which creates and...
What is InputSplit in hadoop?
InputSplit represents the data to be processed by an individual Mapper. it presents a byte-oriented view on the input and...
What is RecordReader in hadoop?
RecordReader reads <key, value> pairs from an InputSplit. Where key and value is- key – the key to read...
What are the most common input formats in Hadoop? Which input format is default one?
These are the most common input formats in Hadoop. Text Input Format Key Value Input Format Sequence File Input...
What are the input formats in hadoop?
These are input formats in hadoop. CombineFileInputFormat, CombineSequenceFileInputFormat, CombineTextInputFormat, CompositeInputFormat, DBInputFormat, FileInputFormat, FixedLengthInputFormat, KeyValueTextInputFormat, MultiFileInputFormat, NLineInputFormat, Parser.Node, SequenceFileAsBinaryInputFormat, SequenceFileAsTextInputFormat,...
What is TextInputFormat and KeyValueInputFormat class?
In Hadoop TextInputFormat reads lines of text files and provides the offset of the line as key to the Mapper...
What is a Combiner in hadoop?
The Combiner in hadoop is a ‘mini-reduce’ process which operates only on data generated by a mapper. The Combiner...