👋 Hey {{first_name|there}},
Why this matters / where it hurts
You know this conversation. Support calls. "The order exists, but Search can't find it." Product frowns. "It looks broken." Engineering shrugs. "Give it a minute."
Nobody likes that answer.
I used to call this a bug. Something technical broke. The broker dropped a message. The consumer lagged behind. The index went stale. So we patched it, retries here, logs there, and a manual reindex button for emergencies. It worked until the next fire.
Here's the real problem: we're forcing ACID behavior across networks that weren't built for it. Some teams grab for 2PC. Others want "one big transaction." The system fights back with locks that freeze, latency that climbs, and coupling so brittle it shatters during deployments. Other teams accept eventual consistency but implement it carelessly, losing events when load spikes or brokers fail, and suddenly you're drowning in the worst of both worlds, stale reads everywhere, and missing facts you'll never recover.
This lesson offers calm. Not perfection. Practicality. We'll treat consistency as an architecture choice you make deliberately for each user flow. Then we'll implement eventual consistency the right way with the Outbox Pattern, guaranteeing that an event is never "maybe published," not even when your broker decides to take an unscheduled vacation.
🧭 Mindset shift
From: "Data mismatch is a bug. Make systems agree instantly."
To: "Consistency is a product and architecture choice. Make propagation reliable."
Want Search and Orders to agree instantly? You're asking for distributed transactions. That means coordinating locks across services or emulating coordination with synchronous calls that pretend to be atomic. Latency rises. Failures amplify. Deployments slow to a crawl.
Eventual consistency isn't surrender. It's a tradeoff. You choose it. The trick is making the propagation path so reliable that "eventual" never becomes "sometimes never."
Two rules that keep you out of trouble
Decide the consistency level per flow. Design the UX and API contract around it.
Publish events transactionally with the write. Otherwise, you'll lose them at the worst possible moment.