Outbox Pattern solves distributed dual-write problem via transactional guarantee

The Outbox Pattern addresses a fundamental distributed systems challenge by eliminating the assumption that updating a database and publishing an event can be an atomic operation. It ensures a committed business change remains linked to its describing event by writing both records in a single local transaction. A separate relay or CDC process then asynchronously publishes the committed event from the outbox table. This pattern does not guarantee exactly-once processing, so event publication can be retried and consumers must be idempotent. At larger scales, performance concerns shift to managing the outbox table, publisher efficiency, and partition key distribution.