Real questions from top companies
Explain how partitioning and bucketing in Hive/Spark optimize queries. What are the trade-offs in bucket count, partition cardinality, and small-file problem? When does over-partitioning or over-bucketing become counterproductive?
Explain the Medallion Architecture (Bronze, Silver, Gold).
Explain the concept of window functions in SQL and provide an example
Explain the difference between Star and Snowflake schemas. When would you choose one over the other?
Explain the difference between partition count and query performance in Spark.
Find average salary for each manager – Assume a table with manager_id and employee_salary
Find each student's previous year's scores using the LAG function.
Find the third-highest salary for each department.
Finding nth Highest Salary within each department
Given a CSV file with raw customer transactions, design an ETL pipeline that cleans data, aggregates total sales by region and product, and loads into target table
Given a dataset, perform transformations: Filter rows where sales > 1000, Add a new column calculating a 10% discount on sales, Group data by region and calculate total revenue.
Given a table with 10 records and another with 4 records, how many records result from a cross join?
Given two dataframes (df1: id, name and df2: id, country, address, city, count), join them, filter for rows where country = 'Singapore', and pivot the output. Sort cities in descending order of population count
How can you automate data insertion into BigQuery using Python?
How can you delete partitions from a table in Hive using a command?
How do you count occurrences in a column in SQL?
How do you design a scalable and fault-tolerant data warehouse on a cloud platform?
How do you interact with Google BigQuery using Python?
How do you keep a specific column on top in SQL?
How many records result from Inner Join, Left Join, Right Join given Table A and Table B?
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