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Apache Spark 2.x for Java Developers

You're reading from  Apache Spark 2.x for Java Developers

Product type Book
Published in Jul 2017
Publisher Packt
ISBN-13 9781787126497
Pages 350 pages
Edition 1st Edition
Languages
Authors (2):
Sourav Gulati Sourav Gulati
Profile icon Sourav Gulati
Sumit Kumar Sumit Kumar
Profile icon Sumit Kumar
View More author details

Table of Contents (19) Chapters

Title Page
Credits
Foreword
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Introduction to Spark 2. Revisiting Java 3. Let Us Spark 4. Understanding the Spark Programming Model 5. Working with Data and Storage 6. Spark on Cluster 7. Spark Programming Model - Advanced 8. Working with Spark SQL 9. Near Real-Time Processing with Spark Streaming 10. Machine Learning Analytics with Spark MLlib 11. Learning Spark GraphX

SQLContext and HiveContext


Prior to Spark 2.0, SparkContext used to be the entry point for Spark applications, an SQLContext and HiveContext used to be the entry points to run Spark SQL. HiveContext is the superset of SQLContext. The SQLContext needs to be created to run Spark SQL on the RDD.

The SQLContext provides connectivity to various data sources. Data can be read from those data sources and Spark SQL can be executed to transform the data as per the requirement. It can be created using SparkContext as follows:

JavaSparkContext javaSparkContext = new JavaSparkContext(conf); 
SQLContext sqlContext = new SQLContext(javaSparkContext); 

The SQLContext creates a wrapper over SparkContext and provides SQL functionality and functions to work with structured data. It comes with the basic level of SQL functions.

The HiveContext, being a superset of SQLContext, provides a lot more functions. The HiveContext lets you write queries using Hive QL Parser ,which means all of the Hive functions can be...

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