Amazon Data Engineer interview questions

1. What difference have you made in current team apart from regular work ? 2. What are the steps you follow to rebuild a table in database ? 3. How did you do performance tuning ? 4. How do you find the skewness of data in table ? 5. Difference between RDBMS and Dimensional Modeling SQL 1) purchase customer_id product_id quantity purchase_date 1 111 1 01/01/2017 1 111 2 01/02/2107 1 222 2 01/02/2017 2 111 3 01/04/2017 2 222 1 01/03/2017 3 222 1 01/05/2017 3 222 1 01/06/2017 3 111 1 01/06/2017 3 111 1 01/04/2017 Q: How many customers bought each product how many times during the week? Product_Id Number_of Customers Number_of_Times 111 2 2 111 1 1 222 2 1 222 1 2 2) daily_usage account_id usage_amount usage_date 1 10 1 1 20 2 1 15 3 1 30 4 Q. a) How do you print the usage_amount of previous/consecutive rows b) Without using window functions