Postgresql Database

• Async Loading: Always use TypeOrmModule.forRootAsync to load secrets from ConfigService.
• Sync: Set synchronize: false in production; use migrations instead.

Migrations

• Never use synchronize: true in production.
• Generation: Whenever a TypeORM entity (.entity.ts) is modified, a migration MUST be generated using pnpm migration:generate.
• Audit: Always inspect the generated migration file to ensure it matches the entity changes before applying.
• Production Strategies:
  • CI/CD Integration (Recommended): Run pnpm migration:run in a pre-deploy or post-deploy job (e.g., GitHub Actions, GitLab CI). Ensure the production environment variables are correctly set.
  • Manual SQL (For restricted DB access): Use typeorm migration:show to get the SQL or simply copy the up method's SQL into a management tool (like Supabase SQL Editor). Always track manual runs in the migrations metadata table.
• Zero-Downtime: Use Expand-Contract pattern (Add -> Backfill -> Drop) for destructive changes.
• Seeding: Use factories for dev data; only static dicts for prod.
• Row-Level Security (RLS): typeorm migration:generate cannot detect RLS policies (CREATE POLICY). You MUST use migration:create and write raw queryRunner.query() SQL to define and version-control RLS policies.

Best Practices

1. Pagination: Mandatory. Use limit/offset or cursor-based pagination.
2. Indexing: Define indexes in code (decorators/schema) for frequently filtered columns (where, order by).
3. Transactions: Use QueryRunner (TypeORM) or $transaction (Prisma) for all multi-step mutations to ensure atomicity.
4. Row-Level Security (RLS) Performance:
   • RLS adds a small overhead to every query on the table because the database must evaluate the policy conditions (e.g., WHERE tenant_id = current_setting('app.tenant_id')).
   • Mitigation: ALWAYS create an index on the columns used in your RLS policies (usually user_id or tenant_id).
   • Warning: Avoid complex JOINs or subqueries inside the RLS policy definition itself, as this can multiply execution time heavily. Keep policies simple (direct column comparisons).