Distributed

Transactional Outbox

Write the event as a row in the same transaction as the state change; a relay publishes it afterwards.

Why interviewers ask about it

Eliminates the dual-write problem. Publishing is at-least-once by construction, which is why consumers must be idempotent.

A sequence of local transactions, each with a compensating action, replacing a distributed transaction.

At-least-once delivery combined with idempotent consumers that deduplicate, committing the dedup record with the side effect.

This term is part of the free System Design interview preparation module - browse the full glossary for every definition.