A compensating transaction must be designed to be idempotent. Why is this property crucial?
Java interview question for Advanced practice.
Answer
To allow the transaction to be safely retried multiple times without causing unintended side effects.
Explanation
Idempotency means that an operation can be performed multiple times with the same result as if it were performed only once. This is critical for compensating transactions because the system (e.g., an orchestrator) might retry sending a compensation command due to network failures or timeouts. If the compensation were not idempotent (e.g., a 'refund' that could be applied multiple times), retries could lead to incorrect system state.