Database Schema Design

Design relational or document schemas from access patterns, cardinality, and lifecycle. Use when modeling entities, choosing embed vs normalize, or shaping schema boundaries before implementation.

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Database Schema Design

Priority: P0 (CRITICAL)

Start from reads, writes, and ownership. Schema follows access patterns, not vice versa.

Rules

  • Model one business concept per table/collection boundary.
  • Choose embed vs reference or normalize vs denormalize from cardinality, update frequency, and read locality.
  • Encode uniqueness, nullability, and foreign-key or ownership rules explicitly.
  • Prefer additive evolution over destructive redesigns.

Verify

  • Hot reads are supported without avoidable joins or fan-out.
  • Cardinality and lifecycle were written down for major relationships.
  • Constraints or validation rules exist for business invariants.
  • IDs, timestamps, and soft-delete semantics are consistent.

Anti-Patterns

  • No schema from ORM defaults: model business access patterns first.
  • No many-to-many without owner rules: define source of truth and cleanup behavior.
  • No nullable drift: nullable fields need lifecycle meaning.

References

HoangNguyen0403/agent-skills-standard/tree/main/skills/database/database-schema-design commit babfd2c401

Frequently asked questions

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