Idempotent writes can go to every region

When a write is safe to repeat and the authoritative copy lives elsewhere, a design can skip replication and promotion entirely: write to every region independently and repair the gaps. The Financial Times ran its content publishing platform across the EU and the US this way.

Two conditions made it work. The platform was not the source of truth for articles; the editorial CMS was, so a lost copy could be fetched again. And publishing was idempotent: doing it twice leaves the same result as doing it once. The regional clusters were treated as entirely separate and each article was published to both. A monitor checked every data store in both regions and alerted if an article had not arrived within two minutes; the repair was to publish again, by hand or with tools that routinely republished recent content.

No region is ever promoted, so Promoting a replica can lose acknowledged writes never comes up, and reconciliation shrinks to a republish. The price is that regions can disagree for a while, and the pattern holds only where a repeat is harmless, which is what Idempotency keys make retries safe tries to arrange for everything else.