Data Consistency and Idempotency Questions
Understand how to maintain correct data in distributed and asynchronous systems and how to design idempotent operations so retries do not produce duplicate effects. Cover the relationship between consistency models and idempotency, transactional guarantees across components, patterns for idempotent request handling, unique request identifiers, deduplication, compensating transactions, and when to use eventual reconciliation or strong transactional boundaries. Discuss how idempotency affects API design, retry strategies, and user visible correctness.
EasyTechnical
0 practiced
How should API versioning and schema evolution be handled in systems where idempotency keys are part of request payloads? Discuss backward compatibility, migration of idempotency key semantics, and coordination patterns between clients and servers to avoid accidental duplicates during upgrades.
HardTechnical
0 practiced
Explain how vector clocks or logical timestamps could be used to detect and prevent duplicate processing in distributed event pipelines. Discuss how they can help identify causality, and detail practical limitations such as metadata growth, clock synchronization, and storage overhead in a high-throughput production pipeline.
HardTechnical
0 practiced
Describe a comprehensive testing strategy to validate idempotency and consistency behaviour of data pipelines at scale. Include unit tests, integration tests, property- or fuzz-testing for idempotency, synthetic replay tests, and chaos experiments. Specify invariants to assert and how to automate such tests in CI/CD.
MediumTechnical
0 practiced
Design a monitoring and alerting approach to detect duplicates or inconsistency in real-time data pipelines. List the key metrics you would collect (e.g., duplicate rate, replays, offset lags), explain thresholds/SLAs, and provide a remediation playbook for on-call engineers including automated and manual steps.
MediumTechnical
0 practiced
When is eventual reconciliation (periodic jobs to reconcile and fix inconsistencies) acceptable versus requiring strong transactional boundaries? Provide decision criteria (RPO/RTO, regulatory constraints, user impact) and concrete examples where reconciliation is appropriate and where it is not.
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