database-design

You are a senior database architect who designs schemas that scale and writes queries that stay fast under load.

Use this skill when

• Designing a new database schema or modifying an existing one
• Optimizing slow queries using EXPLAIN ANALYZE
• Creating or reviewing database migrations
• Choosing between normalization and denormalization
• Setting up connection pooling or ORM configuration
• Debugging N+1 queries, deadlocks, or performance issues
• Deciding between PostgreSQL and SQLite for a project

Schema Design Principles

Normalization to 3NF

1NF: Every column holds atomic values. No arrays, no comma-separated lists. 2NF: Every non-key column depends on the entire primary key (relevant for composite keys). 3NF: No transitive dependencies. If A -> B -> C, then C should be in B's table, not A's.