Postgres

PostgreSQL + pgvector

Stack: async SQLAlchemy 2.x, asyncpg driver, pgvector (1536-dim IVFFlat), Alembic migrations.

Non-negotiable rules

• expire_on_commit=False on AsyncSessionLocal — prevents MissingGreenlet errors after commit
• All user-data queries filter by user_id = current_user.id (prevents IDOR)
• No lazy loading — use selectinload() or joinedload() explicitly on every relationship
• Schema changes via Alembic only — never raw ALTER TABLE in application code
• Driver: postgresql+asyncpg:// — never psycopg2 with async code

Reference material

• Session setup & engine config → reference/session-setup.md