Paytm Interview Experience for Data Engineer ( 2 Years Experienced)

Round 1(Technical) [1hr]:

• Introduction
• Discussion on Project.
• Some SQL questions are easy to difficult level. like
  • Remove duplicates from the table.
  • nth height item in each partition.
  • In one table IPL team’s name give and you have to find a combination of matches to be played between them with some conditions. = use self join
  • Running aggregation on table = use window function with a range
• Some warm-up Coding questions:
  • Freq of each word in a string.
  • Subarray sum equal to K.
  • Merge K sorted list in a single list in a sorted manner.
• Simple Data Structure question :
  • Reverse stack without using extra space.
• Some discussion on Optimization Technique in spark.
• Python Collection.

Round 2(Technical) [1.5 h]:

• Brief Introduction.
• Project discussion and your contribution to project.
• SQL question:
  • Design bank statement from customer table based on debit and credit amount column.
• Warm up coding question:
  • How many char to append, to make string palindrome.
  • Email masking.
• Data Structure Question:
  • Add two numbers represented by linked lists
  • Convert a Binary Tree into its Mirror Tree.
  • Bottom View of Tree.
• Some questions related to Hive and Spark like.
  • Spark Architecture.
  • I have a file with name, address, score as input read file in spark and validate the fields to come up with error score let’s say if the name consists of numeric – error is 10% if address length < 5 then an error is 15% and if the score is less than > 40 then an error is 20% if the record has an error of >= 20% write to error file else write to a success file.
  • Join Optimization in Spark and Hive.
  • Slowly changing dimensions and its types.
  • Some questions related to file format and compression technique.

Round 3(Technical + Managerial) [1.5 h]:

• Brief Introduction.
• Tell me something which is not written in the resume.
• Project architecture discussion and some cross-question why using this tech.
• Some questions related to the cluster configuration.
• Some situation-based questions on spark.
  • If a spark job is taking 5min to complete and after some months it takes 2 hrs. to complete, so what could be the reason for the same.
  • Difference between repartition and coalesce: In which case you will use repartition to decrease the number of partition.
  • What challenges you face in your project.
  • If you have to process 500 GB data and on your cluster, you are having 64 GB ram and 16 core then question is How many executor you will use for this spark job and what will be the configuration of each executor.
  • In which case you will use data warehouse and data lake.
  • Which Data structure you will use to store aadhar card data.
• One Designing Problem of DSA:
  • design snake ladder.
    • find minimum dice roll require to win, if while taking input you are also taking ladder and snake position index.
    • Which data structure you will chose to solve this.
• One Puzzle:
  • There are 5 lanes on a race track. One needs to find out the 3 fastest horses among total of 25. Find out the minimum number of races to be conducted in order to determine the fastest three.

After that HR discussion happened on telephonic call.

This is all about my experience during the Interview process. Hope this will help you.

 All the best!!