LTIMindtree Senior Data Engineer Interview Questions and Answers

Q1. How to handle missing data in pyspark dataframe.
Ans. 
Handle missing data in pyspark dataframe by using functions like dropna, fillna, or replace.
• Use dropna() function to remove rows with missing data

• Use fillna() function to fill missing values with a specified value

• Use replace() function to replace missing values with a specified value
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Q2. Shared some table details and asked to get get maximum salary paid customer for all department from the table using pyspark
Ans. 
Use PySpark to find the maximum salary paid to customers in each department from a given table.
• Load the data into a DataFrame using spark.read.

• Group the data by department using groupBy() method.

• Use agg() function to calculate the maximum salary for each department.

• Example: df.groupBy('department').agg({'salary': 'max'})

• Show the results using show() method.
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Q1. Python sorting test
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Q2. SQL for joining 2 tables
Ans. 
Joining two tables in SQL combines rows based on a related column, enabling comprehensive data analysis.
• Use INNER JOIN to return only matching rows from both tables. Example: SELECT * FROM TableA INNER JOIN TableB ON TableA.id = TableB.a_id;

• LEFT JOIN returns all rows from the left table and matched rows from the right table. Example: SELECT * FROM TableA LEFT JOIN TableB ON TableA.id = TableB.a_id;

• RIGHT JOIN returns al...read more
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Q1. What is Lambda?
Ans. 
Lambda is a serverless computing service that runs code in response to events without provisioning servers.
• Lambda allows you to run code in response to triggers such as HTTP requests via API Gateway.

• It supports multiple programming languages, including Python, Node.js, and Java.

• You only pay for the compute time you consume, making it cost-effective for variable workloads.

• Lambda can be integrated with other AWS services...read more
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Q2. Read and write?
Ans. 
Read and write in data engineering refers to the processes of data ingestion and data output in systems.
• Reading data involves extracting information from various sources like databases, APIs, or files.

• Writing data refers to storing processed or raw data into databases, data lakes, or other storage solutions.

• Example of reading: Using SQL queries to fetch data from a relational database.

• Example of writing: Using ETL tool...read more
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Aptitude test and 2 coding questions

Q1. What is the oops of java
Ans. 
Object-oriented programming concepts in Java
• Encapsulation: bundling data and methods that operate on the data into a single unit

• Inheritance: allows a class to inherit properties and behavior from another class

• Polymorphism: ability of a method to do different things based on the object it is acting upon

• Abstraction: hiding the implementation details and showing only the functionality to the user
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Q2. On your self intrest on technologiea
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Q1. Talk something about your best frds
Ans. 
My best friends are like family to me, always there to support and uplift me.
• They are always there for me in good times and bad.

• We share common interests and hobbies.

• They understand me and accept me for who I am.

• We have created many unforgettable memories together.

• I can always count on them to give me honest advice and feedback.
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Q2. What do you heard about mindtree
Ans. 
Mindtree is an Indian multinational information technology and outsourcing company.
• Founded in 1999

• Headquartered in Bangalore, India

• Provides IT services and consulting

• Acquired by L&T in 2019
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DWT concept based questions, even though questions were perefectly answered, and the interviewer gave a promise note, no call back from them

Spark and Big data related questions

Q1. Salary discussion
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