Define Data Architecture

Objective

Choose database engine, define schema strategy, select data access patterns, and plan migration and caching approaches.

Decisions to Make

1. Database Engine

Choose one (or combination):
- SQLite — File-based, zero config. Best for: desktop apps, prototypes, single-user.
- PostgreSQL — Full-featured relational. Best for: production web apps, complex queries.
- MySQL/MariaDB — Relational, widely supported. Best for: standard web apps.
- Neo4j — Graph database. Best for: relationship-heavy data, graph traversals.
- MongoDB — Document store. Best for: flexible schemas, rapid prototyping.
- Combination — e.g., SQLite for FOB + Neo4j for HOMEBASE.

Document rationale: performance needs, data model fit, team expertise, licensing.

2. Schema Strategy

• Migration tool: Django migrations, Alembic, Flyway, manual SQL
• Versioning: How are schema changes tracked? Numbered migrations? Timestamps?
• Seed data: How is initial/test data loaded? Fixtures, factories, management commands?
• Schema evolution: How are breaking changes handled? Expand-contract pattern?

3. Data Access Patterns

Choose one:
- ORM — Object-Relational Mapping (Django ORM, SQLAlchemy). Best for: standard CRUD.
- Repository Pattern — Abstract interface over storage. Best for: storage-agnostic design, testability.
- Raw Queries — Direct SQL/Cypher. Best for: complex queries, performance-critical paths.
- Hybrid — ORM for simple CRUD + raw queries for complex operations.

4. Read/Write Separation & Caching

• Is read/write separation needed? (CQRS pattern)
• Cache strategy: application-level cache, query cache, HTTP cache
• Cache invalidation approach
• Connection pooling configuration

5. Scan Skills

Query Playbook Skills where capability_domain in:
- DB_RELATIONAL
- DB_GRAPH
- DATA_ACCESS

Report coverage and gaps.

Deliverables

• ✅ Database engine chosen with rationale
• ✅ Schema strategy defined (migrations, versioning, seed data)
• ✅ Data access pattern selected
• ✅ Caching strategy defined (if applicable)
• ✅ Skill coverage assessed for this domain
• ✅ Decision recorded for inclusion in SAO.md (DTA-18)