Revisiting Learned Index with Byte-addressable Persistent Storage
Rui Zhang, Yukai Huang, Sicheng Liang, Shangyi Sun, Shaonan Ma, Chengying Huan, Lulu Chen, Zhihui Lu, Yang Xu, Ming Yan, Jie Wu · 2024
Byte-addressable Persistent Storage (BPS), such as persistent memory and CXL-enabled SSDs, has become an extension of main memory. This opens up new possibilities for indexes that operate and persist data directly on the memory bus. Recent learned indexes exploit data distribution and have shown great potential for some workloads. Despite some work proposed for integrating learned indexes into BPS, they are mainly based on Intel’s first-generation persistent memory. The current design suffers from the following problems: 1) Excessive storage line accesses due to large node in learned indexes; 2) Inefficient concurrency control due to volatile cache; 3) Write amplification due to mismatch access granularity.