Map Reduce

refer to
– https://informationit27.medium.com/hadoop-mapreduce-in-action-b7c723b604ba
– https://www.slideshare.net/mudassarmulla/tutorial-hadoop-hdfsmapreduce
– https://cwiki.apache.org/confluence/display/HADOOP2/JobTracker
– https://www.youtube.com/watch?v=ULtOZqlZnCw

Tools built on top of Map Reduce

• Hive – convert HSQL into Map Reduce, easier coding with SQL alike syntax without java programming. From Facebook.
• Spark

Shortcoming of Map Reduce

• lacks of abstractions for leveraging distributed memory
• write result to external storage system
• inefficient for an important class of emerging application