Multi Step Processes hard
Message A fails and goes to the DLQ. Message B (dependent on A) succeeds. You fix the bug and replay Message A from the DLQ. What is the risk?
- A Message B is deleted.
- B Message A is processed *after* Message B, potentially overwriting newer state with older state (Out-of-Order execution).
- C Message A disappears.
- D The queue jams.
Answer: B. Message A is processed *after* Message B, potentially overwriting newer state with older state (Out-of-Order execution).
DLQ replay breaks chronological order. If A was 'Create User' and B was 'Update User', reprocessing A later might accidentally reset the user's data to the initial state, undoing B's update.
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