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.

EasyTechnical

32 practiced

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.

HardSystem Design

54 practiced

Design a hybrid architecture for a chat application: message timeline must be low-latency and durable, search over messages must support full-text queries and attachments. Choose storage technologies for each requirement, explain the sync strategy, and discuss cost and operational complexity.

MediumTechnical

60 practiced

You need to store documents with occasionally evolving schemas (new optional fields added over time) and frequent reads by id and by a handful of indexed fields. Compare using MongoDB vs. PostgreSQL with JSONB, focusing on indexing, ACID transactions, query expressiveness, tools/operators, and operational maturity.

MediumTechnical

36 practiced

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.

MediumTechnical

34 practiced

Design an index strategy for a table storing 1B rows supporting two query patterns: (A) point lookups by primary key and (B) frequent range queries over a timestamp and status field. Explain trade-offs in index maintenance cost, write amplification, and storage overhead.

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