Difference between SparkContext, JavaSparkContext, SQLContext, and SparkSession?

Question

1. What is the difference between SparkContext, JavaSparkContext, SQLContext and SparkSession?
2. Is there any m

Answer 1

Explanation from spark source code under branch-2.1

SparkContext: Main entry point for Spark functionality. A SparkContext represents the connection to a Spark cluster, and can be used to create RDDs, accumulators and broadcast variables on that cluster.

Only one SparkContext may be active per JVM. You must stop() the active SparkContext before creating a new one. This limitation may eventually be removed; see SPARK-2243 for more details.

JavaSparkContext: A Java-friendly version of [[org.apache.spark.SparkContext]] that returns [[org.apache.spark.api.java.JavaRDD]]s and works with Java collections instead of Scala ones.

Only one SparkContext may be active per JVM. You must stop() the active SparkContext before creating a new one. This limitation may eventually be removed; see SPARK-2243 for more details.

SQLContext: The entry point for working with structured data (rows and columns) in Spark 1.x.

As of Spark 2.0, this is replaced by [[SparkSession]]. However, we are keeping the class here for backward compatibility.

SparkSession: The entry point to programming Spark with the Dataset and DataFrame API.