9 Key-Value Stores Every Developer Should Know for System Design Interviews

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A technical guide published on DEV Community breaks down nine key-value databases to help developers make informed choices during system design interviews. The piece argues that defaulting to Redis without justification signals a lack of depth, since key-value stores span a wide range of use cases from caching to petabyte-scale storage. Each database — including DynamoDB, FoundationDB, Cassandra, Riak, Etcd, RocksDB, LevelDB, and Memcached — is evaluated with specific deploy and avoid scenarios. For example, FoundationDB suits financial systems requiring strict ACID transactions, while Memcached remains optimal for simple, stateless caching without persistence needs. The guide encourages engineers to justify their database choices based on workload characteristics rather than defaulting to popular names.

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