database-designlisted

# database-design SQL schema design, ORM patterns, migration strategies, query optimisation, and data-modelling for relational databases. ## When to use - Design a schema for a multi-tenant SaaS application - Write an Alembic migration to add a non-null column to an existing table - This query takes 4 seconds, help me add the right index - Should I use a junction table or an array column for tags? - Model a user → orders → line-items hierarchy in SQLAlchemy - What constraints should I add to prevent orphaned records? - Explain the difference between 3NF and BCNF - Write a Drizzle ORM schema for a blog with posts, tags, and comments ## When NOT to use - How do I set up PostgreSQL connection pooling with pgBouncer? — Connection pooling config — NOT data modelling - Configure Redis as a session store — NoSQL / caching — out of scope - Set up a Kafka consumer for event streaming — ETL / streaming pipeline — out of scope - How do I back up my PostgreSQL database? — Operations/DBA — not schema engineering ## Anti-patterns ### Symptom Invoking this skill for tasks outside its scope — e.g., infrastructure concerns when the request is about application code, or vice versa. ### Problem Scope mismatch wastes context and produces advice tuned for the wrong domain. A database schema skill answering a connection-pooling question gives schema advice when the real problem is operational configuration. ### Solution Read the NOT for clauses carefully. If the request matches an exclusi