Fragma Data Systems Data Engineer Interview Questions and Answers

Q1. Tell me about yourself, and project architecture. What are your day-to-day responsibilities?
Ans. 
I am a Data Engineer with experience in designing and implementing project architectures. My day-to-day responsibilities include data processing, ETL tasks, and ensuring data quality.
• Designing and implementing project architectures for data processing

• Performing ETL tasks to extract, transform, and load data into the system

• Ensuring data quality and integrity through data validation and cleansing

• Collaborating with cross-...read more
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Q2. SQL: To calculate the difference in marks for each student ID and marks across different years?
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Use SQL to calculate the difference in marks for each student ID across different years.
• Use a self join on the table to compare marks for the same student ID across different years.

• Calculate the difference in marks by subtracting the marks from different years.

• Group the results by student ID to get the difference in marks for each student.
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Q3. SQL: Statewise which gender purchase is the most?
Ans. 
The answer to the question is that in which state which gender makes the most purchases.
• Aggregate the data by state and gender to calculate the total purchases made by each gender in each state.

• Identify the gender with the highest total purchases in each state.

• Present the results in a table or chart for easy visualization.
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Q4. What is ADF ??
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ADF stands for Azure Data Factory, a cloud-based data integration service that allows you to create, schedule, and manage data pipelines.
• ADF is used for building, scheduling, and monitoring data pipelines to move and transform data from various sources to destinations.

• It supports data integration between various data stores such as Azure SQL Database, Azure Blob Storage, and on-premises data sources.

• ADF provides a visu...read more
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Q5. Pysaprk Coding Question?
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Q6. What is DAG ??
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Q7. What is Lineage ??
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Lineage refers to the history and origin of data, including its source, transformations, and dependencies.
• Lineage helps in understanding how data is generated, processed, and transformed throughout its lifecycle.

• It tracks the flow of data from its source to its destination, including any intermediate steps or transformations.

• Lineage is important for data governance, data quality, and troubleshooting data issues.

• Example...read more
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Q8. How does Spark handle fault tolerance?
Ans. 
Spark handles fault tolerance through resilient distributed datasets (RDDs) and lineage tracking.
• Spark achieves fault tolerance through RDDs, which are immutable distributed collections of objects that can be rebuilt if a partition is lost.

• RDDs track the lineage of transformations applied to the data, allowing lost partitions to be recomputed based on the original data and transformations.

• Spark also replicates data par...read more
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Q9. There are four cores and four worker nodes in Spark. How many jobs will run in parallel?
Ans. 
Only one job will run in parallel in Spark with four cores and four worker nodes.
• In Spark, each core can only run one task at a time, so with four cores, only four tasks can run concurrently.

• Since there are four worker nodes, each with four cores, a total of four tasks can run in parallel.

• Therefore, only one job will run in parallel in this scenario.
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Q10. What are the optimisation techniques you have used in your project ?
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Q1. Find duplicate rows in the given table
Ans. 
Identify duplicate rows in a table
• Use SQL query with GROUP BY and HAVING clause to identify duplicate rows based on specific columns

• Example: SELECT column1, column2, COUNT(*) FROM table_name GROUP BY column1, column2 HAVING COUNT(*) > 1
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1.ETL Pipeline
2.PySpark Code
3.SQL

Q1. 1.sql easy question 2.pyspark easy code as I was fesher
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Q2. 1.query related to group by
Ans. 
Group by is a SQL clause used to aggregate data based on one or more columns.
• Used to group rows that have the same values in specified columns.

• Commonly used with aggregate functions like COUNT, SUM, AVG.

• Example: SELECT department, COUNT(*) FROM employees GROUP BY department;

• Can include HAVING clause to filter groups based on aggregate values.

• Example: SELECT department, AVG(salary) FROM employees GROUP BY department HAV...read more
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Q1. 1.One tricky sql query 2.What is sqoop?sqoop performs which job - map or reduce?
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