Data Migration and Consistency Questions
Plan and execute data migrations while preserving correctness and availability. Topics include zero downtime migration techniques, schema evolution patterns, backward and forward compatibility, dual writes and shadow writes, incremental and bulk migration strategies, data validation and reconciliation, canary migrations, rollbacks and fallback plans, and how to minimize user impact during transitions. Understand trade offs between consistency and speed of migration and techniques to detect and correct drift after migration.
MediumTechnical
0 practiced
You're asking product and legal to approve a migration that requires masking certain PII fields for test environments. How would you structure your ask to obtain buy-in quickly? What technical controls and audit evidence would you present to satisfy legal and product concerns?
HardSystem Design
0 practiced
Architect a zero-downtime migration for a petabyte-scale dataset being moved into a cloud-native database that will serve 100k QPS. Include components for initial bulk transfer, continuous change capture, cutover strategy, reconciliation, and cost/operational trade-offs. Assume multi-region read replicas exist.
MediumTechnical
0 practiced
Explain how Slowly Changing Dimensions (SCD) types (1,2,3) affect a migration from OLTP to a data warehouse. Describe mapping decisions, how to backfill history, and reconciliation checks you'd run to validate the migrated analytical model.
EasyTechnical
0 practiced
Explain idempotency in the context of migration write operations. Give two concrete engineering approaches to make writes idempotent when backfilling records into the target database and explain trade-offs for each.
HardTechnical
0 practiced
How would you implement transactional guarantees for dual-write (source DB and target DB) without using distributed two-phase commit? Describe patterns such as the Outbox pattern, Change-Data-Capture-driven writes, and compensation transactions. Explain trade-offs in latency, complexity, and failure modes.
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