Big Data Engineer
70+ Big Data Engineer Interview Questions and Answers

Asked in Impetus Technologies

Q. Difference between partitioning and bucketing. Types of joins in spark Optimization Techniques in spark Broadcast variable and broadcast join Difference between ORC and Parquet Difference between RDD and Datafr...
read moreExplaining partitioning, bucketing, joins, optimization, broadcast variables, ORC vs Parquet, RDD vs Dataframe, project architecture and responsibilities for Big Data Engineer role.
Partitioning is dividing data into smaller chunks for parallel processing, while bucketing is organizing data into buckets based on a hash function.
Types of joins in Spark include inner join, outer join, left join, right join, and full outer join.
Optimization techniques in Spark include caching, re...read more

Asked in TCS

Q. What optimization techniques have you utilized in your projects? Please explain with specific use cases.
I have utilized optimization techniques such as indexing, caching, and parallel processing in my projects.
Implemented indexing on large datasets to improve query performance
Utilized caching to store frequently accessed data and reduce load times
Implemented parallel processing to speed up data processing tasks
Big Data Engineer Interview Questions and Answers for Freshers

Asked in Carelon Global Solutions

Q. Given the following data: col1 100 100 200 200 300 400 400 400 Using PARTITION BY col1, how do you get the rank as shown below? col1 rank 100 1 100 1 200 1 200 1 300 1 400 1 400 1 400 1
Using SQL's RANK function with PARTITION BY to assign ranks based on col1 values.
RANK() function assigns a unique rank to each distinct value in the partition.
Identical values receive the same rank, and the next rank is skipped.
Example: For values 100, 100, the rank is 1 for both.
For values 200, 200, the rank is also 1 for both, continuing this pattern.

Asked in Micron Technology

Q. Write a program to check if a Fibonacci number is present within a specified range (100-200).
To check if a Fibonacci number is present between 100-200
Generate Fibonacci numbers until 200
Check if any number is between 100-200
Use dynamic programming to optimize Fibonacci generation

Asked in TCS

Q. What is the difference between lineage and directed acyclic graphs (DAG)?
Lineage tracks the history of data transformations, while DAG is a graph structure with nodes representing tasks and edges representing dependencies.
Lineage focuses on the history of data transformations, showing how data has been derived or modified.
DAG is a graph structure where nodes represent tasks and edges represent dependencies between tasks.
Lineage helps in understanding the data flow and ensuring data quality and reliability.
DAG is commonly used in workflow managemen...read more

Asked in Impetus Technologies

Q. How do you handle upserts in Spark?
Spark can handle upserts using merge() function
Use merge() function to handle upserts in Spark
Specify the primary key column(s) to identify matching rows
Specify the update column(s) to update existing rows
Specify the insert column(s) to insert new rows
Example: df1.merge(df2, on='id', whenMatched='update', whenNotMatched='insert')
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Asked in TCS

Q. What is the difference between cache and persistence?
Cache is temporary storage used to store frequently accessed data for quick retrieval, while persistence refers to storing data permanently.
Cache is temporary and volatile, while persistence is permanent and non-volatile
Cache is typically faster to access than persistence
Examples of cache include browser cache, CPU cache, and in-memory cache systems like Redis
Examples of persistence include databases like MySQL, PostgreSQL, and file systems like HDFS

Asked in Innova Solutions

Q. Spark and hadoop architectural difference , DAG, What is stage boundaries , Partitioning and bucketing in hive
Spark and Hadoop have different architectures. DAG is a directed acyclic graph. Stage boundaries are logical divisions in a Spark job. Hive has partitioning and bucketing.
Spark is an in-memory processing engine while Hadoop is a distributed file system.
DAG is a graph of stages in a Spark job.
Stage boundaries are logical divisions in a Spark job that help optimize execution.
Partitioning in Hive is a way to divide a table into smaller, more manageable parts based on a column.
Bu...read more
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Asked in Citicorp

Q. What is the difference between an internal and external table in Hive?
Internal tables store data in a Hive-managed warehouse while external tables store data outside of Hive.
Internal tables are managed by Hive and are stored in a Hive warehouse directory
External tables are not managed by Hive and can be stored in any location accessible by Hive
Dropping an internal table also drops the data while dropping an external table only drops the metadata
Internal tables are faster for querying as they are stored in a Hive-managed warehouse
External tables...read more

Asked in Impetus Technologies

Q. SQL question Remove duplicate records 5th highest salary department wise
Remove duplicate records and find 5th highest salary department wise using SQL.
Use DISTINCT keyword to remove duplicate records.
Use GROUP BY clause to group the records by department.
Use ORDER BY clause to sort the salaries in descending order.
Use LIMIT clause to get the 5th highest salary.
Combine all the above clauses to get the desired result.

Asked in Micron Technology

Q. How do you convert a list of dictionaries to CSV format using Python?
Convert a list of dictionaries to CSV in Python
Use the csv module to write to a file or StringIO object
Use the keys of the first dictionary as the header row
Loop through the list and write each dictionary as a row

Asked in PwC

Q. If we have streaming data coming from Kafka and Spark, how will you handle fault tolerance?
Implement fault tolerance by using checkpointing, replication, and monitoring mechanisms.
Enable checkpointing in Spark Streaming to save the state of the computation periodically to a reliable storage like HDFS or S3.
Use replication in Kafka to ensure that data is not lost in case of node failures.
Monitor the health of the Kafka and Spark clusters using tools like Prometheus and Grafana to detect and address issues proactively.

Asked in PwC

Q. If you have a large dataset to load that will not fit into memory, how would you load the file?
Use techniques like chunking, streaming, or distributed processing to load large datasets that exceed memory limits.
Chunking: Load data in smaller, manageable pieces. For example, using pandas in Python: pd.read_csv('file.csv', chunksize=1000).
Streaming: Process data on-the-fly without loading it all into memory. Use libraries like Dask or Apache Kafka.
Distributed Processing: Utilize frameworks like Apache Spark or Hadoop to distribute the data across multiple nodes.
Database ...read more

Asked in Wipro

Q. How do you tune Spark's configuration settings to optimize query performance?
Spark configuration settings can be tuned to optimize query performance by adjusting parameters like memory allocation, parallelism, and caching.
Increase executor memory and cores to allow for more parallel processing
Adjust shuffle partitions to optimize data shuffling during joins and aggregations
Enable dynamic allocation to scale resources based on workload demands
Utilize caching to store intermediate results and avoid recomputation
Monitor and analyze query execution plans ...read more

Asked in Wipro

Q. What strategies do you use to handle data skew and partition imbalance in Spark?
To handle data skew and partition imbalance in Spark, strategies include using salting, bucketing, repartitioning, and optimizing join operations.
Use salting to evenly distribute skewed keys across partitions
Implement bucketing to pre-partition data based on a specific column
Repartition data based on a specific key to balance partitions
Optimize join operations by broadcasting small tables or using partitioning strategies

Asked in Cognizant

Q. What is speculative execution in Hadoop?
Speculative execution in Hadoop is a feature that allows the framework to launch duplicate tasks for a job, with the goal of completing the job faster.
Speculative execution is used when a task is taking longer to complete than expected.
Hadoop identifies slow-running tasks and launches duplicate tasks on other nodes.
The first task to complete is used, while the others are killed to avoid duplication of results.
This helps in improving job completion time and overall efficiency ...read more

Asked in LTIMindtree

Q. Explain higher order function, closure, anonymous function, map, flatmap, tail recursion
Higher order functions, closures, anonymous functions, map, flatmap, and tail recursion are key concepts in functional programming.
Higher order function: Functions that can take other functions as arguments or return functions as results.
Closure: Functions that capture variables from their lexical scope, even when they are called outside that scope.
Anonymous function: Functions without a specified name, often used as arguments to higher order functions.
Map: A function that ap...read more

Asked in Infosys

Q. What is Spark, and why is it faster than Hadoop?
Spark is a fast and distributed data processing engine that can perform in-memory processing.
Spark is faster than Hadoop because it can perform in-memory processing, reducing the need to write intermediate results to disk.
Spark uses DAG (Directed Acyclic Graph) for processing tasks, which optimizes the workflow and minimizes data shuffling.
Spark allows for iterative computations, making it suitable for machine learning algorithms that require multiple passes over the data.
Spa...read more

Asked in Innominds Software

Q. 1. Java vs Python 2. Normalizations 3. Why mongodb 4. Program to reverese linkedlist (just the idea) 5. Cloud Computing
Interview questions for Big Data Engineer role
Java and Python are both popular programming languages for Big Data processing, but Java is preferred for its performance and scalability
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity
MongoDB is a NoSQL database that is highly scalable and flexible, making it a good choice for Big Data applications
To reverse a linked list, iterate through the list and change the directi...read more

Asked in Wissen Technology

Q. What is partitioning in Hive?
Partitioning in Hive is a way of dividing a large table into smaller, more manageable parts based on a specific column.
Partitioning improves query performance by reducing the amount of data that needs to be scanned.
Partitions can be based on date, region, or any other relevant column.
Hive supports both static and dynamic partitioning.
Partitioning can be done on external tables as well.

Asked in Tata Technologies

Q. What are the various operators in the C programming language?
C programming language has various operators for performing operations on variables and values.
Arithmetic Operators: +, -, *, /, % (e.g., a + b)
Relational Operators: ==, !=, >, <, >=, <= (e.g., a > b)
Logical Operators: &&, ||, ! (e.g., a && b)
Bitwise Operators: &, |, ^, ~, <<, >> (e.g., a & b)
Assignment Operators: =, +=, -=, *=, /= (e.g., a += b)
Increment/Decrement Operators: ++, -- (e.g., a++)

Asked in PubMatic

Q. Given a list of numbers, find the number of pairs that sum to a specific target value.
Count pairs in an array that sum up to a target value.
Iterate through the array and store the frequency of each element in a hashmap.
For each element, check if the difference between the target and the element exists in the hashmap.
Increment the count of pairs if the difference is found in the hashmap.

Asked in Virtusa Consulting Services

Q. What type of file system did you use in your project?
We use Hadoop Distributed File System (HDFS) for our project.
HDFS is a distributed file system designed to run on commodity hardware.
It provides high-throughput access to application data and is fault-tolerant.
HDFS is used by many big data processing frameworks like Hadoop, Spark, etc.
It stores data in a distributed manner across multiple nodes in a cluster.
HDFS is optimized for large files and sequential reads and writes.

Asked in Alibaba Group

Q. What is the difference between Spark and Hadoop MapReduce?
Spark is faster than Hadoop MapReduce due to in-memory processing and supports multiple types of workloads.
Spark performs in-memory processing, while Hadoop MapReduce writes to disk after each task.
Spark supports multiple types of workloads like batch processing, interactive queries, streaming data, and machine learning, while Hadoop MapReduce is mainly for batch processing.
Spark provides higher-level APIs in Java, Scala, Python, and R, making it easier to use than Hadoop Map...read more

Asked in Cognizant

Q. How do you add data into a partitioned Hive table?
To add data into a partitioned hive table, you can use the INSERT INTO statement with the PARTITION clause.
Use INSERT INTO statement to add data into the table.
Specify the partition column values using the PARTITION clause.
Example: INSERT INTO table_name PARTITION (partition_column=value) VALUES (data);

Asked in Barclays Shared Services

Q. Explain the Hadoop Architecture.
Hadoop Architecture is a distributed computing framework that allows for the processing of large data sets.
Hadoop consists of two main components: Hadoop Distributed File System (HDFS) and MapReduce.
HDFS is responsible for storing data across multiple nodes in a cluster.
MapReduce is responsible for processing the data stored in HDFS by dividing it into smaller chunks and processing them in parallel.
Hadoop also includes other components such as YARN, which manages resources in...read more

Asked in EXL Service

Q. What is the difference between RANK and DENSE_RANK in SQL?
Rank assigns a unique rank to each distinct row, while dense rank assigns consecutive ranks to rows with the same values.
Rank function assigns unique ranks to each distinct row in the result set
Dense rank function assigns consecutive ranks to rows with the same values
Rank function leaves gaps in the ranking sequence if there are ties, while dense rank does not

Asked in Virtusa Consulting Services

Q. What command is used to check disk utilization and health in Hadoop?
Use 'hdfs diskbalancer' command to check disk utilisation and health in Hadoop
Run 'hdfs diskbalancer -report' to get a report on disk utilisation
Use 'hdfs diskbalancer -plan <path>' to generate a plan for balancing disk usage
Check the Hadoop logs for any disk health issues

Asked in PubMatic

Q. Given an array of integers that is initially increasing and then decreasing, find a target value using a binary search approach.
Binary search can be used to solve moderate problems of arrays that are first increasing and then decreasing.
Use binary search to find the peak element in the array, which marks the transition from increasing to decreasing.
Divide the array into two parts based on the peak element and apply binary search on each part separately.
Handle edge cases such as when the array is strictly increasing or strictly decreasing.
Example: ['1', '3', '5', '7', '6', '4', '2']

Asked in PwC

Q. What are the core components of Spark?
Core components of Spark include Spark Core, Spark SQL, Spark Streaming, MLlib, and GraphX.
Spark Core: foundation of the Spark platform, provides basic functionality for distributed data processing
Spark SQL: module for working with structured data using SQL and DataFrame API
Spark Streaming: extension of the core Spark API that enables scalable, high-throughput, fault-tolerant stream processing of live data streams
MLlib: machine learning library for Spark that provides scalabl...read more
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