Altimetrik Gcp Data Engineer Interview Questions and Answers

Q1. Which of these 2 select * from table and select * from table limit 100 is faster
Ans. 
select * from table limit 100 is faster
• Using 'select * from table' retrieves all rows from the table, which can be slower if the table is large

• Using 'select * from table limit 100' limits the number of rows retrieved, making it faster

• Limiting the number of rows fetched can improve query performance
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Q2. Explain scd and Merge in bigquery
Ans. 
SCD stands for Slowly Changing Dimension and Merge is a SQL operation used to update or insert data in BigQuery.
• SCD is used to track changes to data over time in a data warehouse

• Merge in BigQuery is used to perform insert, update, or delete operations in a single statement

• Example: MERGE INTO target_table USING source_table ON condition WHEN MATCHED THEN UPDATE SET col1 = value1 WHEN NOT MATCHED THEN INSERT (col1, col2)
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Q3. Architecture of bigquery
Ans. 
BigQuery is a fully managed, serverless data warehouse that enables scalable analysis over petabytes of data.
• BigQuery uses a columnar storage format for efficient querying.

• It supports standard SQL for querying data.

• BigQuery allows for real-time data streaming for analysis.

• It integrates with various data sources like Google Cloud Storage, Google Sheets, etc.

• BigQuery provides automatic scaling and high availability.
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Q4. Dataflow function to split sentence
Ans. 
Dataflow function to split sentence
• Use the Split transform in Dataflow to split the sentence into words

• Apply ParDo function to process each word individually

• Use regular expressions to handle punctuation and special characters
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Q1. Explain your project
Ans. 
Developed a data pipeline to ingest, process, and analyze customer feedback data for a retail company.
• Used Google Cloud Platform services like BigQuery, Dataflow, and Pub/Sub for data processing.

• Implemented data cleansing and transformation techniques to ensure data quality.

• Created visualizations and dashboards using tools like Data Studio for stakeholders to easily interpret the data.
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Q2. GCP bigquery architecture
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Q3. Gcp object versioning
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Q4. Gcp storage class types
Ans. 
GCP offers different storage classes for varying performance and cost requirements.
• Standard Storage: for frequently accessed data

• Nearline Storage: for data accessed less frequently

• Coldline Storage: for data accessed very infrequently

• Archive Storage: for data stored for long-term retention
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Q5. Sql optimisation techniques
Ans. 
SQL optimization techniques focus on improving query performance by reducing execution time and resource usage.
• Use indexes to speed up data retrieval

• Avoid using SELECT * and instead specify only the columns needed

• Optimize joins by using appropriate join types and conditions

• Limit the use of subqueries and instead use JOINs where possible

• Use EXPLAIN to analyze query execution plans and identify bottlenecks
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Q6. Sql coding date format and joins related questions
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Q7. Partitioning and cluster by
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Q1. Advanced sql recursive cte and python code using lambda function to explode the list
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Q2. Project explanation and daily activity and challenge faced in project
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Standard Aptitude questions

Based on strings and array

Q1. Background questions and technical questions related to problem solved
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Q1. Technical round was purely based on end to end Power BI Technical questions
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Q1. Management round was based on past career experience and challenges faced
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