Real Time Apache and Scala Multiple Choice Questions And Answers pdf

11. What is an “RDD Lineage”?
Spark does not support data replication in the memory. In the event of any data loss, it is rebuilt using the “RDD Lineage”. It is a process that reconstructs lost data partitions.

12. What is a “Spark Driver”?
“Spark Driver” is the program that runs on the master node of the machine and declares transformations and actions on data RDDs. The driver also delivers RDD graphs to the “Master”, where the standalone cluster manager runs.

13. What is SparkContext?
“SparkContext” is the 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.

14. What is Hive on Spark?
Hive is a component of Hortonworks’ Data Platform (HDP). Hive provides an SQL-like interface to data stored in the HDP. Spark users will automatically get the complete set of Hive’s rich features, including any new features that Hive might introduce in the future.

The main task around implementing the Spark execution engine for Hive lies in query planning, where Hive operator plans from the semantic analyzer which is translated to a task plan that Spark can execute. It also includes query execution, where the generated Spark plan gets actually executed in the Spark cluster.

15. Name a few commonly used Spark Ecosystems.
Spark SQL (Shark)
Spark Streaming
GraphX
MLlib
SparkR

16. What is “Spark Streaming”?
Spark supports stream processing, essentially an extension to the Spark API. This allows stream processing of live data streams. The data from different sources like Flume and HDFS is streamed and processed to file systems, live dashboards and databases. It is similar to batch processing as the input data is divided into streams like batches.
Business use cases for Spark streaming: Each Spark component has its own use case. Whenever you want to analyze data with the latency of less than 15 minutes and greater than 2 minutes i.e. near real time is when you use Spark streaming

17. What is “GraphX” in Spark?
“GraphX” is a component in Spark which is used for graph processing. It helps to build and transform interactive graphs.

18. What is the function of “MLlib”?
“MLlib” is Spark’s machine learning library. It aims at making machine learning easy and scalable with common learning algorithms and real-life use cases including clustering, regression filtering, and dimensional reduction among others.

19. What is “Spark SQL”?
Spark SQL is a Spark interface to work with structured as well as semi-structured data. It has the capability to load data from multiple structured sources like “textfiles”, JSON files, Parquet files, among others. Spark SQL provides a special type of RDD called SchemaRDD. These are row objects, where each object represents a record.
Here’s how you can create an SQL context in Spark SQL:
        SQL context: scala> var sqlContext=new SqlContext
        HiveContext: scala> var hc = new HIVEContext(sc)

20. What is a “Parquet” in Spark?
“Parquet” is a columnar format file supported by many data processing systems. Spark SQL performs both read and write operations with the “Parquet” file.

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