Data Partitioning and Sharding Questions

Techniques and operational practices for horizontally partitioning data across multiple database instances or storage nodes to achieve scale, improve performance, and manage growth. Includes selection and design of partition and shard keys to evenly distribute load and avoid hotspots, with range based, hash based, and directory based approaches and consistent hashing mechanisms. Covers handling uneven distribution and data skew, hotspot detection and mitigation, and the impact of partitioning on query patterns such as joins and cross shard queries. Explains implications for transactions and consistency, including transactional boundaries that span partitions and approaches to distributed transactions and compensation. Describes resharding and online data migration strategies, rolling rebalances, and methods to minimize downtime and data movement. Emphasizes operational concerns including shard management, automation, monitoring and alerting, failure recovery, and performance tuning. Discusses trade offs between simplicity, latency, throughput, and operational complexity and highlights considerations for both transactional and analytical workloads, including routing, caching, and coordination patterns.

MediumTechnical

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Write an operational playbook for recovering from a single-shard failure that causes read/write errors for a subset of users. Include detection, immediate mitigation steps, data integrity checks, and post-recovery validation steps relevant to a sharded SQL database.

MediumTechnical

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Explain the role of virtual nodes (vnodes) in consistent hashing. What are the trade-offs in choosing the number of vnodes per physical node, and how would you explain the implications to an infrastructure manager responsible for capacity planning?

EasyTechnical

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How does horizontal partitioning affect cross-shard JOINs and complex queries? Describe three strategies to handle join-heavy workloads and the trade-offs for each strategy from an operational and latency perspective.

MediumTechnical

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Design a monitoring and alerting plan specifically to detect and respond to shard imbalance and hotspot formation. Include metrics, alert thresholds, automated remediation candidates, and dashboard elements you would provide to SREs and on-call engineers.

EasyTechnical

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List the most important operational metrics and alerts you would implement to monitor the health of a sharded database cluster (think capacity, performance, balance). For each metric explain the reason for monitoring it and a sensible threshold or alerting strategy.

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