How to prepare for Booking.com tech interview (Backend role)

Hey all, created a new template on how to successfully prepare for the „Software Engineer I – Backend“ position at Booking.com

Please feel free to use for your next tech interview(applicable not only for booking actually): https://prepto.tech/blog/preparing-for-software-engineer-i-backend-role-at-bookingcom

Example of Question & Answer for topic „Database Design and Optimization“:

Q: How would you optimize a slow-performing SQL query that joins multiple tables with millions of records?

A:

For Booking.com’s scale, I would implement the following optimization strategies:

1. Analyze query execution plan using EXPLAIN to identify bottlenecks
2. Optimize indexes based on WHERE, JOIN, and ORDER BY clauses
3. Consider denormalization for frequently accessed data
4. Implement materialized views for complex aggregations
5. Use partitioning for large tables (e.g., by date for historical booking data)
6. Consider vertical partitioning to split rarely used columns
7. Implement query caching using Redis for frequently accessed data
8. Use LIMIT and pagination to handle large result sets
9. Consider using covering indexes for better performance