Database Design

Database Design

Schema Design Principles

• Normalize first — eliminate redundancy, then denormalize only for proven performance needs
• Name clearly — user_id not uid, created_at not ts
• Every table needs — a primary key, created_at, updated_at
• Soft deletes — add deleted_at instead of hard deleting rows you might need to recover

Relationship Patterns

Indexing Strategy

Rule: Index columns you filter, sort, or join on frequently.

-- Index for common query patterns
CREATE INDEX idx_orders_user_status ON orders(user_id, status);
CREATE INDEX idx_posts_created ON posts(created_at DESC);

-- Partial index for active records only
CREATE INDEX idx_active_users ON users(email) WHERE deleted_at IS NULL;

When NOT to Over-Index

• Every index slows down writes
• Index columns with low cardinality (boolean, status with 3 values) only if queries are very frequent
• Monitor query performance, add indexes based on actual slow queries