Combiner (HDFS + MapReduce)

• Combiner is what? it is a mini reducer.
• To decrease the network traffic and increase the performance we use the combiner
• After removing the same key,value pairs from each collection out of mappercode, the unique key,value pairs are sent to the combiner block.
• Each mapper or input split has its own combiner and combining the output of all combiner make the reducer into action and hence the reducer gives the output of all in the O/P file.