Database Architecture and Optimization Questions

Designing and tuning data storage systems to meet requirements for availability, latency, throughput, and cost. Topics include choosing between managed relational services and NoSQL key value or document stores, data modelling and schema design, partitioning and sharding strategies, replication and read replica patterns, indexing and query optimization, transaction and consistency trade offs, connection pooling and resource management, caching and cache invalidation strategies, backup and retention policies, capacity planning and monitoring, and approaches for migrating or scaling databases in production. Candidates should be able to discuss concrete techniques for improving performance, diagnosing slow queries, and balancing operational complexity against performance and cost.