What is Apache Crunch Hadoop?

Hi Durga Sir,

Could u please explain what is Apache Crunch Hadoop ? how it is different from the Hadoop 2.0 or Yarn ?

thanks in advance

The Apache Crunch Java library provides a framework for writing, testing, and running MapReduce pipelines. Its goal is to make pipelines that are composed of many user-defined functions simple to write, easy to test, and efficient to run.