Mactores Engineer Interview Questions and Answers

Q1. Java hash map and how it works
Ans. 
Java hash map is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values based on keys.
• HashMap in Java implements the Map interface and allows null keys and values.

• It uses hashing to store and retrieve key-value pairs, providing O(1) time complexity for get() and put() operations.

• Example: HashMap map = new HashMap<>(); map.put("key", 1); int value = map.get("key");
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First round was coding round that comprised of 4 questions, 1 sql and 3 programming questions. Out of 3, if you are able to run 2 code successfully, you'll qualify for the next round

Q1. In this round, interviewer will ask basic interview questions first, then they'll give multiple sql questions, few questions based on spark and few programming questions
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Q1. Difference between Spark and MapReduce. Spark joins like broadcast and sort merge
Ans. 
Spark is faster than MapReduce due to in-memory processing and DAG execution.
• Spark uses DAG (Directed Acyclic Graph) execution while MapReduce uses batch processing.

• Spark performs in-memory processing while MapReduce writes to disk after each operation.

• Spark has a more flexible programming model with support for multiple languages.

• Spark has built-in libraries for machine learning, graph processing, and stream processin...read more
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Q2. Spark file formats like parquet, orc, avro etc. Which one you are using and why
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Q3. Spark optimization techniques
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Spark optimization techniques improve performance and efficiency of Spark applications.
• Partitioning data to reduce shuffling

• Caching frequently used data

• Using broadcast variables for small data

• Tuning memory allocation and garbage collection

• Using efficient data formats like Parquet

• Avoiding unnecessary data shuffling

• Using appropriate hardware configurations

• Optimizing SQL queries with appropriate indexing and partitioning
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Q4. Basic programming language based questions
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Q5. Hive- partition vs bucketing
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Hive partitioning is dividing data into smaller, manageable parts while bucketing is dividing data into equal parts based on a hash function.
• Partitioning is useful for filtering data based on a specific column

• Bucketing is useful for evenly distributing data for faster querying

• Partitioning can be done on multiple columns while bucketing is done on a single column

• Partitioning creates separate directories for each partiti...read more
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Q6. Hive optimization techniques
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Hive optimization techniques improve query performance and reduce execution time.
• Partitioning tables to reduce data scanned

• Using bucketing to group data for faster querying

• Using vectorization to process data in batches

• Using indexing to speed up lookups

• Using compression to reduce storage and I/O costs
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Q7. Recent projects you've worked on
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Q8. SQL based questions, window functions
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Q1. Why do you want to switch
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Q2. Have you ever faced any problem in previous projects, how you handled that
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Q1. Questions related to SAP BW and HANA
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Q1. Questions related to SAP BW and HANA
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Q1. Reason for Job Change
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90 min coding test with 4-5 problems to solve

Q1. Technical rounds mostly goes around the project work ans some were based on the JD.
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Asked get write python code for a perticular scenario

Q1. Salary discussion happened
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Q1. Questions on tomcat, java., spring
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Q1. Q on OOPS, Resume based projects in detail
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Q1. Standard HR questions
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Q1. About previous rolls
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Q2. Whaat did you di
Ans. 
I successfully implemented a new project management system to streamline workflow and improve team efficiency.
• Implemented new project management system

• Streamlined workflow

• Improved team efficiency
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