Dealing With Contention hard
In a Saga, if a Compensating Transaction (Undo) fails repeatedly due to contention, what is the last resort?
- A Ignore it.
- B Retry forever.
- C Human Intervention. The system parks the transaction in a 'Dead Letter Queue' for an operator to manually fix the data inconsistency.
- D Delete the user.
Answer: C. Human Intervention. The system parks the transaction in a 'Dead Letter Queue' for an operator to manually fix the data inconsistency.
You cannot rollback a rollback. If automatic recovery fails, manual reconciliation is the storage of last resort.
One system design question a day, with spaced repetition so the ones you miss come back.
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