Atlassian Senior Data Engineer Interview Questions and Answers

Q1. How did you ingest kafka data and you day to day activity
Ans. 
I ingested Kafka data using Kafka Connect and performed data processing and analysis on a daily basis.
• Used Kafka Connect to ingest data from various sources into Kafka topics

• Developed custom Kafka Connect connectors for specific data sources

• Utilized Kafka Streams for real-time data processing and analysis

• Worked with schema registry for data serialization and deserialization
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Q2. What is catalyst optimizer
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Catalyst optimizer is a query optimization framework in Apache Spark that improves performance by generating optimized query plans.
• Catalyst optimizer is a rule-based optimization framework in Apache Spark.

• It leverages advanced techniques like predicate pushdown, constant folding, and join reordering to optimize query plans.

• Catalyst optimizer helps in improving the performance of Spark SQL queries by selecting the most ...read more
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I was asked two SQL questions.
The first was to find customers who liked both apples and oranges. The second one was to find the customer with the highest order value

Basic Python, SQL, and Bash questions

Q1. SQL questions with operations that include changing from string to array. Tip: stick to RDBMS-specific dialects only (like Postgres), I used Spark SQL
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Q2. Simple Python questions with a follow-up to optimise it
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Q3. Bash script-based questions, are pretty basic.
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Q4. Data pipeline design and best practices.
Ans. 
Data pipeline design involves creating a system to efficiently collect, process, and analyze data.
• Understand the data sources and requirements before designing the pipeline.

• Use tools like Apache Kafka, Apache NiFi, or AWS Glue for data ingestion and processing.

• Implement data validation and error handling mechanisms to ensure data quality.

• Consider scalability and performance optimization while designing the pipeline.

• Doc...read more
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Q1. Easy to medium Leetcode-based question. With moderate difficulty.
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Q2. Simple Python-based question with optimisation.
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Q3. Design specific questions based on Data pipelines.
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Q1. SQL-based question with moderate difficulty.
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Q2. Python-based questions, follow questions with some optimisations.
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Q3. Bash-script based round.
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Q1. Find longest palindromic substring in a given string.
Ans. 
Use dynamic programming to find the longest palindromic substring in a given string.
• Iterate through the string and expand around each character to find palindromes.

• Store the length of the longest palindrome found so far.

• Return the substring based on the start and end indices of the longest palindrome.
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Q2. How to serialize and deserialise a tree
Ans. 
To serialize and deserialize a tree, use a recursive approach to traverse the tree and store the data in a suitable format.
• Use pre-order traversal to serialize the tree by storing the node values in a list or string.

• For deserialization, reconstruct the tree by recursively building nodes from the serialized data.

• Consider using JSON or XML format for serialization to easily store and retrieve tree structure.
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Q3. Find if a given regex (containing ., * and lower case english chars) matches a given string.
Ans. 
Use regex library to match given regex with string.
• Use a regex library like re in Python to match the given regex with the string.

• Check if the regex matches the string using the library functions.

• Handle cases where the regex contains special characters like . and * appropriately.
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Q4. Explain about throttling and implement throttle function.
Ans. 
Throttling is a technique used to control the rate of requests sent to a server.
• Throttling helps prevent server overload by limiting the number of requests processed at a time.

• Implementing a throttle function involves setting a maximum request rate and delaying excess requests.

• Example: Implementing a throttle function in a web application to limit the number of API calls made to a third-party service.

• Example: Throttlin...read more
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Q1. Find squares of elements in a sorted array and return the sorted response.
Ans. 
Sort the squares of elements in a sorted array and return the sorted response.
• Iterate through the array and square each element.

• Store the squared values in a new array.

• Sort the new array and return it.
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Q2. Write a short promise example and implement your own promise
Ans. 
A promise is a commitment to do something in the future, typically used for asynchronous operations in JavaScript.
• Promises are used to handle asynchronous operations in JavaScript.

• They represent a value that may be available now, in the future, or never.

• Promises have three states: pending, fulfilled, or rejected.

• Example: new Promise((resolve, reject) => { setTimeout(() => resolve('Done!'), 1000); });
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Q3. Explain event loop, what are different types of queues in event loop
Ans. 
Event loop is a mechanism that allows for asynchronous execution of code by managing the order of events in a single thread.
• Event loop continuously checks the call stack for any functions that need to be executed, and processes them in a non-blocking manner.

• Different types of queues in event loop include microtask queue (Promise callbacks), macrotask queue (setTimeout, setInterval callbacks), and animation frame queue
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Q4. What is virtual DOM and why its faster
Ans. 
Virtual DOM is a lightweight copy of the actual DOM, used to improve performance by minimizing direct manipulation of the real DOM.
• Virtual DOM is a concept used in frameworks like React to optimize rendering performance.

• Changes are first made to the virtual DOM, which is then compared to the real DOM to identify the minimal updates needed.

• This approach reduces the number of actual DOM manipulations, resulting in faster...read more
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Q1. Reverse the linked list.
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Q1. Internel working of Hashmap
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Q1. Salary Discussion
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Q1. Tell me about your experience?
Ans. 
I have over 8 years of experience in software development, specializing in backend systems and database management.
• Developed scalable backend systems using Java and Spring framework

• Designed and optimized database schemas for performance

• Led a team of developers in implementing new features and resolving technical issues

• Worked on integrating third-party APIs for enhanced functionality
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Q2. Asked deeply on my current project?
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Q3. What are difficulties you faced in your work?
Ans. 
Difficulties faced include complex technical challenges, tight deadlines, and communication issues.
• Complex technical challenges such as optimizing performance of a large-scale system

• Tight deadlines requiring quick turnaround on projects

• Communication issues with team members or stakeholders leading to misunderstandings
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