Level hashing is a write-optimized and high-performance hashing index scheme for persistent memory, with low-overhead consistency guarantee and cost-efficient resizing. Level hashing provides a sharing-based two-level hash table, which achieves a constant-scale search/insertion/deletion/update time complexity in the worst case and rarely incurs extra NVM writes. To guarantee the consistency with low overhead, level hashing leverages log-free consistency schemes for insertion, deletion, and resizing operations, and an opportunistic log-free scheme for update operation. To cost-efficiently resize this hash table, level hashing leverages an in-place resizing scheme that only needs to rehash 1/3 of buckets instead of the entire table, thus significantly reducing the number of rehashed buckets and improving the resizing performance.
To learn more, please read our papers:
-
Pengfei Zuo, Yu Hua, Jie Wu, “Write-Optimized and High-Performance Hashing Index Scheme for Persistent Memory”, in Proceedings of the 13th USENIX Symposium on Operating Systems Design and Implementation (OSDI), 2018.
-
Pengfei Zuo, Yu Hua, Jie Wu, "Level Hashing: A High-performance and Flexible-resizing Persistent Hashing Index Structure", ACM Transactions on Storage (TOS), Volume 15, Issue 2, Article No. 13, June 2019.
- level_hashing: The code for single-threaded level hashing, run in DRAM platform.
- concurrent_level_hashing: The code for concurrent level hashing, run in DRAM platform.
- persistent_level_hashing: The code for persistent level hashing, run in the simulated NVM platform, i.e., Quartz.
If you have any questions about level hashing, please feel free to contact me.
Email: pfzuo@hust.edu.cn
Homepage: https://pfzuo.github.io/