Data Consistency and Error Handling Questions

Cover strategies for maintaining correct and reliable data across services and for surfacing and recovering from errors. Topics include consistency models such as strong consistency and eventual consistency patterns for distributed transactions including two phase commit and compensating transactions design of idempotent operations retry logic conflict detection and reconciliation implications of replication and sharding and validation at multiple layers. Candidates should describe error propagation and user facing messaging instrumentation monitoring for data divergence and practical approaches for reconciling inconsistent state.