Succinct and Fast Tiny Pointer Hash Tables

2026-07-30

AI Summary

Existing hash tables struggle to simultaneously achieve high operational speed and space efficiency. This work proposes Tiny Pointer Hash Tables (TPHT), the first practical hash table design that engineeringly integrates succinct pointers and compact key encoding, supporting dynamic resizing without global pauses and fully accommodating 64-bit keys. TPHT combines pointer compression, compact key representation, and two data layouts—chained and flattened—to ensure cache-friendly memory access and constant-time operations. Experimental results demonstrate that Chained-TPHT attains a space efficiency of 105.4%, while Flattened-TPHT achieves up to an 89.3% throughput improvement at 83.4% space efficiency, substantially advancing the latency–space Pareto frontier for hash table implementations.

Abstract

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.

Problem

• hash tables
• memory overhead
• performance
• space efficiency
• pointer compression

Innovation

• succinct data structures
• pointer compression
• hash tables
• space efficiency
• cache-efficient design