Kafka vs a Message Queue: Why Events Stay After Reading

In this chapter

Keep the event after someone reads it

What breaks

A queue deletes TripRequested once one worker takes it. The worker crashes. The trip is gone, and pricing never saw it.

Three ways to respond

• Add a second queue: Still deleted after one read. No replay.
• Write it to a Kafka log: The event stays. Every reader keeps its own place. (the fix)
• Let the phone retry: The app may create the trip twice.

The fix: Write it to a Kafka log

A queue gives each item to one worker, then forgets it. Kafka keeps events for a set time, and each consumer group remembers its own position (offset).

Remember: Reading does not delete. Retention does.

More on Basics problems

• Kafka Topics vs Partitions and Message Keys Explained
• Kafka Producer Batching: Async Send, linger.ms, batch.size
• Event-Driven Architecture with Kafka: Drop Sync Calls
• Kafka Fan-Out: One Event, Many Consumer Groups

Keep learning

• Previous: Kafka Interview Questions: 26 Real Production Problems
• Next: Kafka Topics vs Partitions and Message Keys Explained
• All Kafka tutorial chapters

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