Why this chapter matters
Solid schema design prevents update anomalies and makes analytics easier to trust over time.
What you will learn
- Define primary keys, foreign keys, and essential constraints.
- Apply normalization principles to reduce redundant storage.
- Balance normalized design with query readability and performance.
Lessons in this chapter
- Relational modeling basicsModel entities and relationships with clear table boundaries. Read the full guide →
- Normal forms in practiceUse practical first, second, and third normal form checks.
- Constraints as guardrailsEnforce invariants with NOT NULL, UNIQUE, CHECK, and foreign keys in PostgreSQL.
- Schema choices and analyticsEvaluate how modeling decisions affect downstream query complexity.
Study task
Redesign a denormalized PostgreSQL orders sheet into customer, order, and order_item tables with keys and constraints.
Chapter checkpoint
Why is a foreign key useful in PostgreSQL table design?
A foreign key enforces referential integrity so related records cannot drift into invalid states.