tl;dr: Co-locating workflow state and application data in the same Postgres database lets you commit both in a single transaction, eliminating the idempotency and atomicity problems that plague durable workflow engines. This means transactional steps get exactly-once semantics without bookkeeping tables, and you can replace the transactional outbox pattern by enqueuing workflows via a UDF in the same transaction as your app updates. The post is from DBOS, which builds a Postgres-backed durable execution framework around this idea.