Facebook data engineering interview questions are bilingual, product-analytics-flavored, and PostgreSQL-grounded on the SQL side. Facebook Inc. rebranded to Meta Platforms Inc. in October 2021, but the data-engineering interview shape — and the question patterns that show up in the live phone screen and onsite — has not moved. The standard technical phone screen is 5 minutes intro + 30 minutes SQL + 30 minutes Python + 5 minutes Q&A , with the candidate choosing whether to start with SQL or Python. Four primitives carry the loop: n*(n+1)/2 - sum(arr) arithmetic-series sum-formula (and its XOR self-cancellation alternative) for the missing-number array problem, character-by-character tokenization plus two-pass evaluation for arithmetic formula parsing, correlated EXISTS subqueries with EXTRACT(MONTH FROM ts - INTERVAL '1 month') for month-over-month MAU retention, and CTE composition plus self-joins for post-hiatus aggregation and friend-recommendation queries.…