SQLAlchemy

Handle an optimistic version conflict with SQLAlchemy

Uses SQLAlchemy version counters and an HTTP precondition to reject stale writes without silently overwriting newer state.

How do SQLAlchemy's identity map and unit of work affect ORM behavior?

Explains object identity, tracked changes, flush ordering, and the limits of session-level caching.

How do you choose between lazy loading, joined loading, select-in loading, and raise-on-access in SQLAlchemy?

Chooses relationship loading from cardinality, query count, result size, and hidden-I/O boundaries.

How do you size and diagnose a SQLAlchemy connection pool?

Connects pool limits to process topology, transaction duration, database capacity, and queueing evidence.

How should a SQLAlchemy service handle stale pooled connections and database timeouts?

Separates stale checkout protection, connection aging, pool waits, statement timeouts, and uncertain transactions.

How should you scope SQLAlchemy sessions across requests, threads, and async tasks?

Defines one explicit SQLAlchemy session and transaction owner for each request, job, thread, or async task.

Python Backend

Python backend interview preparation grounded in real service development.

A backend-focused Python preparation path covering language semantics, typing, FastAPI, Django, concurrency, data access, testing, security, background work, reliability, and production diagnosis.