Database Scalability and High Availability Questions

Architectural approaches and operational practices for scaling and maintaining database availability. Topics include vertical versus horizontal scaling trade offs; replication topologies, leader and follower roles, read replicas and replica lag; read write splitting and connection pooling; sharding and partitioning strategies including range based, hash based, and consistent hashing approaches; handling hot partitions and data skew; federation and multi database federation patterns; cache layers and cache invalidation; rebalancing and resharding strategies; distributed concurrency control and transactional guarantees across shards; multi region deployment strategies, cross region failover and disaster recovery; monitoring, capacity planning, automation for failover and backups, and cost optimization at scale. Candidates should be able to pick scaling approaches based on read and write patterns and explain operational complexity and trade offs introduced by distributed data.

MediumSystem Design

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Describe a safe plan for rebalancing data when adding capacity to a sharded relational database with live traffic. Cover chunk selection, throttling, routing updates during migration, consistency verification, and rollback strategies in case of failures mid-reshard.

MediumSystem Design

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A client has a single-region relational DB serving 5,000 RPS that is >90% reads. They want lower latency and higher availability without large cost increases. As a Solutions Architect, propose a pragmatic architecture addressing replication, caching, consistency expectations, failover steps, and an incremental rollout plan.

MediumTechnical

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Compare design approaches for distributed transactions across shards: two-phase commit (2PC), the Saga pattern (compensating transactions), and application-level coordination. For each approach, describe the transactional guarantees, operational complexity, failure modes, and when a Solutions Architect would choose it.

EasyTechnical

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Define sharding and partitioning in databases. Explain the differences and overlap between the terms, list common partitioning strategies (range, hash, list), and describe how each strategy affects query routing, joins, and operational complexity for a large transactional system.

EasyTechnical

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Explain how read replicas work in both traditional RDBMS and distributed database systems. Describe causes of replica lag, how lag affects read consistency and user-facing behavior, monitoring signals to detect lag, and practical mitigation strategies you would recommend to a customer.

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