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

45 practiced

Compare managed service options for a globally distributed user data store: AWS RDS (with read replicas), DynamoDB global tables, Google Cloud Spanner, and a self-managed CockroachDB cluster. Discuss how each handles consistency, latency, operational burden, cost patterns, and vendor lock-in for a full-stack team.

HardSystem Design

44 practiced

Assume Elasticsearch is used as the primary datastore for product search and analytics. Enumerate operational failure modes (index corruption, split-brain, slow recovery), and propose mitigations including snapshot/restore practices, reindexing strategies, graceful degradation during outage, and cost/benefit of hot/warm/cold tiering.

HardTechnical

43 practiced

Propose monitoring, alerting, and SLOs for a full-stack application that uses multiple datastores (RDBMS for transactions, NoSQL for sessions, search for product discovery). What metrics should be collected per store, how do you convert them to user-facing SLOs (frontend latency and error budgets), and how would you structure runbooks for database incidents?

MediumSystem Design

43 practiced

For a multi-terabyte relational database with an RPO of 15 minutes and RTO of 2 hours, propose a backup and restore architecture. Discuss continuous backups, point-in-time recovery (PITR), WAL shipping, cross-region replication, snapshots, and how you would test restore procedures and meet the RTO/RPO.

EasyTechnical

41 practiced

What is a partition key (shard key) in distributed databases? Explain why choosing a good partition key matters for scalability and performance, and list three common mistakes that lead to hot partitions or uneven data distribution.

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