Database design: the schema decisions that haunt you later

Third normal form (3NF) eliminates redundancy and protects data integrity. It's the right choice for transactional systems where data accuracy is critical. But read-heavy applications often benefit from denormalization — duplicating data to avoid joins. The modern answer: normalize your source of truth (OLTP), denormalize your read layer (OLAP or materialized views). Don't try to serve both workloads with the same schema.