- name
- sqlalchemy-code-review
- description
- Reviews SQLAlchemy code for session management, relationships, N+1 queries, and migration patterns. Use when reviewing SQLAlchemy 2.0 code, checking session lifecycle, relationship() usage, or Alembic migrations.
SQLAlchemy Code Review
Quick Reference
Review Checklist
- [ ] Sessions use context managers (
with, async with) - [ ] No session sharing across requests or threads
- [ ] Sessions closed/cleaned up properly
- [ ]
relationship() uses appropriate lazy strategy - [ ] Explicit
joinedload/selectinload to avoid N+1 - [ ] No lazy loading in loops (N+1 queries)
- [ ] Using SQLAlchemy 2.0
select() syntax, not legacy query() - [ ] Bulk operations use bulk_insert/bulk_update, not ORM loops
- [ ] Async sessions use proper async context managers
- [ ] Migrations are reversible with
downgrade() - [ ] Data migrations use
op.execute() not ORM models - [ ] Migration dependencies properly ordered
Gates (SQLAlchemy-specific)
Run once per SQLAlchemy-related finding, after you can anchor file:line (see review-verification-protocol) and before the finding ships. If a step’s pass condition is not met, do not assert the finding as written—gather evidence, withdraw, downgrade severity, or rephrase as a question.
Gate 1 — Session scope and lifecycle
| Step | Action | Pass condition |
|---|
| 1a | Open the module where the session is created or injected (not from memory). | file:line for Session, sessionmaker, async_session, or the factory/Depends() that yields a session. |
| 1b | If claiming leak, cross-request sharing, or missing cleanup: trace the session’s scope (context manager, try/finally, middleware). | Scoped region cited with a file:line range, or withdraw if scope is correct after the read. |
Gate 2 — N+1, lazy loading, eager loads
| Step | Action | Pass condition |
|---|
| 2a | Identify the loop or repeated call site (ORM attribute access, execute in a loop). | file:line for the loop or hot path. |
| 2b | If claiming N+1: name the relationship or query pattern emitted per iteration. | Relationship or per-iteration SQL pattern with file:line, or rephrase as a question if unclear. |
Gate 3 — Migrations (Alembic)
| Step | Action | Pass condition |
|---|
| 3a | Open the revision file (e.g. under versions/, or the project’s Alembic layout). | Repo-relative path + file:line for revision / upgrade / downgrade. |
| 3b | If claiming broken downgrade() or risky data migration: point at the op.* / op.execute() involved. | Snippet or line range in that file for each claimed op, or withdraw. |
When to Load References
- Reviewing session creation/cleanup → sessions.md
- Reviewing model relationships → relationships.md
- Reviewing database queries → queries.md
- Reviewing Alembic migration files → migrations.md
Review Questions
- Are all sessions properly managed with context managers?
- Are relationships configured to avoid N+1 queries?
- Are queries using SQLAlchemy 2.0
select() syntax? - Are all migrations reversible and properly tested?
