Wonder Werkz Data Engineer Interview Questions and Answers

Q1. Spark related questions
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Q2. Previous projects done
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Developed a real-time data processing system for a retail company to optimize inventory management.
• Designed and implemented data pipelines to ingest, process, and analyze large volumes of data

• Utilized technologies like Apache Kafka, Spark, and Hadoop for real-time processing

• Built dashboards and reports for stakeholders to monitor inventory levels and make data-driven decisions
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Q1. 1- Tell me about yourself 2- Spark questions (Architecture, Dag, Lineage,Broadcast, Accumulator, Repartition,coalesce,cache,persist,etc) 3- Basic Pyspark coding problem 4- Python coding problem(Array) 5- ...read more
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Q1. 1- Tell me about yourself 2- Spark architecture 3- Parquet vs avro 4- catalyst optimiser 5- external table vs managed table vs cluster table 6- GIL in python 7- Memory management in python 8- Data skewnes...read more
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General Aptitude test

Q1. On SQL functions
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Q2. Python coding questions
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Q1. Cloud Computing
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Q2. Spark Programming
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Q1. Python, sql, aws
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Q1. Aws, architecture and design
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Q1. Cultural fit and compensation
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Mostly Aptitude, Reasoning,Verbal in the round-1 with 60 questions

2 programming questions - you can select which language u are comfortable

Q1. It's purely based on your resume, so which language u are comfortable they can prefer to ask that's the thing
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Q1. Asked to write a program to check whether string is valid or not. String consists of only three kind of special characters "(), [], {}". We need to return true if all special characters are in correct for...read more
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Q2. What is useRef hook used for?
Ans. 
useRef hook is used to persist a mutable value across renders without causing a re-render.
• Used to store mutable values that do not trigger re-renders.

• Commonly used for accessing DOM elements or storing previous values.

• Does not cause a re-render when the value changes.
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Q3. What are the best practices to avoid rerenders and to improve performance
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Use memoization, virtual DOM, and shouldComponentUpdate to avoid unnecessary rerenders and improve performance.
• Implement memoization to store the result of expensive function calls and avoid recalculating them.

• Use virtual DOM to efficiently update only the parts of the UI that have changed.

• Override shouldComponentUpdate to prevent unnecessary rerenders by comparing current and next props/state.
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Q4. What are callbacks, Promises, async await
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Callbacks, Promises, async await are asynchronous programming concepts in JavaScript.
• Callbacks are functions passed as arguments to another function to be executed later.

• Promises are objects representing the eventual completion or failure of an asynchronous operation.

• async await is a syntax for writing asynchronous code that looks synchronous, making it easier to read and maintain.

• Example: Using a callback to handle th...read more
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Q1. Duplicate in list
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Find duplicates in a list of elements.
• Iterate through the list and keep track of elements seen so far

• If an element is already in the seen elements, it is a duplicate

• Use a hash set to efficiently check for duplicates
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Q2. Anagram in list
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Check if any two strings in the list are anagrams of each other
• Iterate through the list and for each string, sort the characters and check if it already exists in a hashmap

• If it exists, then the current string is an anagram of the existing string

• Return true if anagrams are found, false otherwise
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