简洁快速的微型指针哈希表
Succinct and Fast Tiny Pointer Hash Tables
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中文总结 AI 辅助
本文提出微型指针哈希表（TPHT），含链式、扁平两种互补设计，在保持顶尖性能的同时大幅降低内存使用，推进了延迟-空间帕累托前沿。
中文摘要 AI 辅助
哈希表是许多系统的关键路径，但现代设计仍需在快速操作与高内存开销间权衡。本文重新审视该权衡，提出微型指针哈希表（Tiny Pointer Hash Tables, TPHT），这是一类实用哈希表，将理论中的两个思路应用于系统规模：将指针压缩至1字节，紧凑编码密钥以减少元数据需求。我们将这些思路转化为两种互补设计：链式TPHT追求最大空间节省，据我们所知是首个简单实用的简洁哈希表设计，实现的内存占用小于总数据大小，且操作时间为常数；扁平TPHT追求低延迟，组织数据使常见情况仅需一次缓存未命中，同时保持高效空间利用率。两种变体均支持无全局暂停的动态扩容，可与64位密钥和值无缝集成。在YCSB及微基准测试中，TPHT推进了延迟-空间帕累托前沿：链式TPHT空间效率达105.4%，扁平TPHT空间效率为83.4%，吞吐量较强基线最高提升89.3%。这些结果表明，理论层面的技术可转化为可投入生产的哈希表，在实现顶尖性能的同时显著降低内存使用。
英文摘要
Hash tables sit on the critical path of many systems, yet modern designs still force a trade-off between fast operations and high memory overhead. We revisit this trade-off and present Tiny Pointer Hash Tables (TPHT), a family of practical hash tables that make two ideas from theory work at system scale: compressing pointers down to a byte, and encoding keys compactly so less metadata is needed. We engineer these ideas into two complementary designs. Chained-TPHT targets maximal space savings, and is to the best of our knowledge the first simple and practical succinct hash table design, achieving a footprint less than the total data size with constant-time operations. Flattened-TPHT targets latency, organizing data to keep the common case within a single cache miss while retaining strong space efficiency. Both variants support dynamic resizing without global pauses and integrate cleanly with 64-bit keys and values. Across YCSB and microbenchmarks, TPHT advances the latency-space Pareto frontier: Chained-TPHT reaches 105.4% space efficiency, and Flattened-TPHT achieves 83.4% space efficiency with up to 89.3% higher throughput than strong baselines. Together, these results show that techniques primarily known in theory can be turned into production-ready hash tables that meaningfully reduce memory use while delivering state-of-the-art performance.
