Kafka Message Ordering: Global vs Per-Key Order

In this chapter

One order for everything means one lane

What breaks

A flash sale wants every order in exact arrival order. The topic has 12 partitions.

Three ways to respond

• Sort by timestamp in the consumer: Clocks and late events break this.
• One partition, or your own sequence numbers: Gives up some speed on purpose. (the fix)
• Go to 48 partitions: More lanes. Still no single order.

The fix: One partition, or your own sequence numbers

Kafka orders records only inside a partition. A total order needs one partition, which caps throughput.

Remember: Global order = one partition = one lane.

More on Ordering problems

• Kafka Hot Partition: Choosing the Right Message Key

Keep learning

• Previous: Kafka Outbox Duplicates: Dedupe by Event ID, Not Offset
• Next: Kafka Hot Partition: Choosing the Right Message Key
• All Kafka tutorial chapters

More courses

• Jobs, linked to lessons — Browse jobs where every requirement links to the chapter that teaches it. See how ready you are, how long the gap takes to close, and which listings look stale.
• Match a job post to courses — Paste a job post. Each skill is matched to a track here and put in learning order, foundations first.
• React from open source with patterns — Patterns extracted from Material UI, Radix, React Aria, React Hook Form, Redux Toolkit, TanStack, and Next.js — not slides about hooks.
• Database in depth — How a query becomes work. Indexes, isolation, locks, and the plans that explain why a page is slow — not an ORM tour.
• System Design — Core concepts first (SQL vs NoSQL, CAP, indexing, replication, sharding), then designs grouped by what carries them: the database, Redis, Kafka, or many services.
• Microservices — Microservice patterns one diagram at a time: how to split a monolith, how services talk, and how data stays consistent without distributed transactions.
• Frontend system design — How a UI is sliced when it is a product, not a page: ownership of state, cache, routes, and what happens when the network lies.
• TypeScript in depth — The type system as a design tool. Inference, narrowing, generics, and the errors that mean the model is wrong — not a catalog of utility types.
• CSS in depth — See the box, then the page. Visual chapters from the box model through Flexbox surprises, Grid, selectors, and units, then backgrounds, shapes, and visual effects, each with a playground.
• Accessibility — Foundations first (WCAG in plain words, semantic HTML, lists, alt text), then hands-on HTML labs, a full pass of WAI-ARIA 1.3, and a final fix-the-page challenge.
• Docker — What an image is, why layers cache, and how containers find each other on a network.
• Redis — Fifteen Redis patterns, one picture each: cache, session, lock, counter, rate limiter, queue, and when Redis is the wrong tool.