Comcast India Engineering Center Data Engineer 3 Interview Questions and Answers

It was well designed

Q1. Basic Questions about data warehousing
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Q2. Dbt Scenarios
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Q1. Basicn details to check for qualifications
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Q1. About my projects
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Q1. More details about ML models
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Python Programming related questions, along with one advanced SQL query problem. The final question was a Data Science project on prediting sales potential of various outlets.

Q1. Pattern based - Three memory chips, each of 1GB. You have to store 3GB of data in these chips in such a way that even if one memory chip is corrupted, no data is lost.
Ans. 
Use RAID 5 to store data across all three memory chips with parity bits for fault tolerance.
• Implement RAID 5 to distribute data and parity bits across all three memory chips.

• If one memory chip is corrupted, the data can be reconstructed using the parity bits from the other two chips.

• Example: Store 1GB of data on each chip and use the remaining space for parity bits to ensure fault tolerance.
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Q2. DSA question - Get the longest common prefix string from a list of strings
Ans. 
Find the longest common prefix string from a list of strings.
• Iterate through the characters of the first string and compare with corresponding characters of other strings

• Stop when a mismatch is found or when reaching the end of any string

• Return the prefix found so far
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Q3. DBMS question - What are joins and what are their types?
Ans. 
Joins are used in DBMS to combine rows from two or more tables based on a related column between them.
• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN returns rows when there is at least one match in both tables.

• LEFT JOIN returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN returns all rows from the right table and the matched rows from the left tab...read more
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Q4. ML and DL question - Activation functions, Exploding and Vanishing Gradient problems, LSTM and GRU models frameworks and differences.
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Was taken by the product manager employed in the company. Basic case study question regarding a ride share app planning to expand internationally.

A formal orientation and introduction with the VP and founder of ION India

Q1. Introduce yourself and mention your work that makes you relevant for the job.
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Q2. Is there any correlation between algorithms and law?
Ans. 
Algorithms and law can be correlated through the use of algorithms in legal processes and decision-making.
• Algorithms can be used in legal research to analyze large amounts of data and identify patterns or trends.

• Predictive algorithms can be used in legal cases to assess the likelihood of success or failure.

• Algorithmic tools can help in legal document review and contract analysis.

• However, there are concerns about bias i...read more
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Q1. Cache vs persist
Ans. 
Cache is used for temporary storage of data in memory, while persist is used for saving data to disk for long-term storage.
• Cache is typically faster as it stores data in memory for quick access.

• Persist saves data to disk for durability and long-term storage.

• Cache is often used for temporary data that can be recomputed if lost, while persist is used for important data that needs to be retained.

• Examples: Using cache for ...read more
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Q2. Broadcast join and other optimization techniques
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Q1. Sql window function
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Q2. Spark architecture, dataframe vs rdd
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Q3. Python reverse sentence
Ans. 
Reverse a sentence using Python
• Split the sentence into words using split() method

• Reverse the list of words using list slicing

• Join the reversed list of words back into a sentence using join() method
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Q4. Join based on nulls in sql
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Q1. Probability related
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Q2. Stats related like IQR etc.
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Q1. Difference between entropy & information gain
Ans. 
Entropy measures randomness in data, while information gain measures the reduction in uncertainty after splitting data.
• Entropy is used in decision trees to measure impurity in a dataset before splitting it.

• Information gain is used in decision trees to measure the effectiveness of a split in reducing uncertainty.

• Entropy ranges from 0 (pure dataset) to 1 (completely impure dataset).

• Information gain is calculated as the d...read more
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Q2. LSTM & GRU, Which to use when ?
Ans. 
LSTM for longer sequences, GRU for faster training and less complex models.
• Use LSTM for tasks requiring long-term dependencies and memory retention.

• Use GRU for faster training and simpler models with fewer parameters.

• Consider using LSTM for tasks like language translation or speech recognition.

• Consider using GRU for tasks like sentiment analysis or text generation.
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Time Series data were given, we have to provide some insights

Q1. Tell me about your self?
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Q2. What technology & tools u know ? And basic questions regarding that topics ?
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Q1. Job culture and job responsibilities ?
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Q2. Some questions on an analytical tools like power BI ?
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Q1. About the project and technical aspect
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