Amazon ElastiCache vs Ristretto

Amazon ElastiCache is a managed caching service compatible with Valkey, Memcached, and Redis OSS, with performance described as microsecond latency. Customers can deploy a serverless cache or a node-based cluster. ElastiCache Serverless monitors compute, memory, and network use and scales vertically and horizontally as demand changes. It replicates data across multiple Availability Zones and offers a 99.99% availability SLA for each cache. Listed uses include application and semantic caching, data and session stores, and leaderboards. It can act as a front-end cache for Amazon RDS, Aurora, DocumentDB, and DynamoDB, and improve performance with EC2 and EMR. Security options include encryption in transit and at rest, IAM authentication, Valkey or Redis OSS AUTH, and role-based access control. CloudWatch provides more than 40 operational metrics at no additional charge. Valkey serverless pricing starts at $6 a month, billed according to stored data in GB-hours and requests measured in ECPUs. Data tiering is unavailable with ElastiCache Serverless.

Ristretto is a free, open-source Go library for an in-process cache of key-value data, designed for concurrent use, performance and correctness. It keeps data in memory in a single process rather than operating as a distributed cache. TinyLFU admission and SampledLFU eviction are paired to target high hit ratios; applications define item cost, allowing a valuable large item to displace several smaller ones. The project attributes throughput to contention management, batching and eventual consistency. Goroutines can use the cache concurrently with little throughput degradation, according to the project, and optional metrics cover throughput, hit ratios and other statistics. A Set for a new item may be dropped in the Set buffer or admission policy, while updates are guaranteed. Ristretto requires Go 1.21 or later and Go modules. Version 2 supports generics, which the project recommends for new programs. The repository is licensed under Apache License, Version 2.0, and describes the library as production-ready. Its README names Badger and Dgraph as projects using it.