Apache Spark Interview Questions for various topics.
To perform a cumulative sum by group in a PySpark DataFrame, we can use the `Window` function along with `cumsum()`. This allows us to partition the data by a specific group and then perform the cumulative sum within each group. Below is an example to demonstrate how this can be done in PySpark. Step-by-Step Process …
How to Perform Cumulative Sum by Group in Python Spark DataFrame? Read More »
The parameters `partitionColumn`, `lowerBound`, `upperBound`, and `numPartitions` are used in Apache Spark, particularly when reading data from a database using Spark’s `JDBC` data source. These parameters are key to optimizing the parallelism and partitioning of your data read operations. Here’s an explanation of each parameter: PartitionColumn The `partitionColumn` specifies the column used to partition the …
To access S3A files using Apache Spark, you need to configure Spark to use the s3a protocol, which is an implementation provided by Hadoop-AWS. This will allow Spark to read from and write to AWS S3 using Hadoop’s FileSystem API. Below is a detailed explanation on how to configure and use S3A with Spark, along …
How Can You Access S3A Files Using Apache Spark? Read More »
In Apache Spark, the plan truncation warnings indicate that Spark is encountering difficulties in compiling the physical execution plan due to its complexity. This can occur when dealing with significant nested queries or a large number of joined tables. To resolve these issues, you can manually simplify the execution plan by breaking it into smaller …
How to Resolve Spark’s Plan Truncation Warnings with Manual Aggregation Expressions? Read More »
In Apache Spark, writing a single CSV file without creating a folder is often required for ease of use and compatibility with other systems. By default, Spark writes the output of a DataFrame into multiple parts within a folder. However, we can coalesce the DataFrame into a single partition before writing it to a CSV …
How to Write a Single CSV File in Apache Spark Without Creating a Folder? Read More »
Unpacking a list for selecting multiple columns in a Spark DataFrame is a common task when you need to dynamically select columns based on a list of column names. This can be particularly useful in scenarios where the columns to select are determined at runtime. Below, I’ll show you how to achieve this in PySpark. …
How to Unpack a List for Selecting Multiple Columns in a Spark DataFrame? Read More »
Error handling is a crucial part of working with Apache Spark. One common error that developers encounter while working with Spark, specifically PySpark, is the “Expected Zero Arguments for Classdict Construction” error. This error often arises due to an issue with class decorators or the incorrect use of RDDs and DataFrames. Let’s explore what causes …
How to Resolve Spark Error: Expected Zero Arguments for Classdict Construction? Read More »
Understanding which operations preserve the order of elements in an RDD (Resilient Distributed Dataset) is crucial for scenarios where the sequence of data matters. Not all operations in Apache Spark maintain the order of elements in an RDD. Let’s discuss some common operations and whether they preserve order or not. Operations that Preserve Order Here …
Which Operations Preserve RDD Order in Apache Spark? Read More »
Apache Spark applications may encounter the error “java.lang.OutOfMemoryError: GC Overhead Limit Exceeded” when the Garbage Collector (GC) spends too much time trying to free up memory without making significant progress. This error generally indicates that the JVM is spending more than 98% of its time doing GC and freeing less than 2% of the heap …
Why Does Apache Spark Fail with java.lang.OutOfMemoryError: GC Overhead Limit Exceeded? Read More »
To generate a Spark Schema (StructType) from a case class, you can use Scala’s case class feature along with Spark’s `Encoders` and `ScalaReflection` utilities. This approach leverages the strong type inference features of Scala to automatically derive the schema. Generate a Spark Schema from a Case Class in Scala Let’s go through the steps to …
How to Generate a Spark StructType/Schema from a Case Class? Read More »
