Database Selection and Trade Offs Questions

How to evaluate and choose data storage systems and architectures based on workload characteristics and business constraints. Coverage includes differences between relational and nonrelational families such as document stores, key value stores, wide column stores, graph databases, time series databases, and search engines; mapping query patterns and latency requirements to storage options; trade offs between strong consistency and eventual consistency and their impact on availability and complexity; partition key design, replication strategies, and high availability considerations; operational concerns including backups, monitoring, vendor and cost trade offs, migration or hybrid strategies, and when to adopt polyglot persistence. Senior level discussion includes selecting specific managed services and reasoning about expected load patterns, failure modes, and operational burden.

MediumTechnical

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Your team must decide between managing a self-hosted database vs using a managed cloud DB service. List operational responsibilities each option imposes, and describe how you would quantify 'operational burden' and compute a cost comparison beyond pure dollar cost (include time-to-recovery, maintenance windows, and staffing).

EasyTechnical

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Explain polyglot persistence. Provide two concrete scenarios in which adopting multiple specialized datastores yields clear benefits and two scenarios where polyglot persistence adds too much complexity and should be avoided.

MediumTechnical

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Write a brief migration plan to move an application from MySQL to Amazon DynamoDB for a read-heavy leaderboard feature. Include steps for data export/import, handling foreign-key-like relationships, ensuring zero-downtime reads, and eventual rollback strategy.

EasyTechnical

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You must choose a DB type for storing telemetry metrics (time series) from IoT devices sending a datapoint every 10 seconds per device. Explain why a time-series database (TSDB) might be preferable to a general-purpose relational DB. List three TSDB-specific features that are helpful and any limitations of TSDBs for other workloads.

MediumTechnical

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Implement (in pseudocode or the language of your choice) a function that computes a partition node for time-based rolling windows (e.g., daily partitions) and routes writes to the correct partition. Assume partitions are named data_YYYYMMDD and may not yet exist (lazy creation). Show concurrency considerations for creating partitions.

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