At Meta, teams running experiments on surfaces like Facebook Feed or Instagram Reels need schemas that support both reliable analysis and efficient SQL querying. A weak design makes it hard to answer basic questions like who was assigned, when they were exposed, and whether they converted.
Explain how you would design a PostgreSQL schema to track A/B test assignments and outcomes. Your answer should cover:
The interviewer expects a practical schema design discussion grounded in SQL analytics. Focus on table structure, join paths, event timestamps, deduplication strategy, and trade-offs between normalized event tables and pre-aggregated outcome tables.