Hadoop MapReduce 2.0

Introduction

• MapReduce is a programming model and an associated implementation for processing and generating large data sets
• Users specify a map function that processes a key/value pair to generate a set of intermediate key/value pairs, and a reduce function that merges all intermediate values associated with the same intermediate

Projection Pushdown

Projection pushdown minimizes data transfer betweenMapR Databaseand the Apache Spark engine by omitting unnecessary fields from table scans. It is especially beneficial when a table contains many columns.