Halo: A Hybrid PMem-DRAM Persistent Hash Index with Fast Recovery

Hash index, a fundamental component in many data management systems, can benefit from the emerging persistent memory (PMem) to achieve high performance and instant recovery. However, existing persistent hash indexes are suboptimal in at least three aspects. First, their performance suffers from the mismatch between small random write and access granularity of PMem hardware. Second, none of them are aware of the significance of write amplification caused by memory allocators and synchronization primitives. Third, hybrid designs (PMem+DRAM) focus on improving throughput at the cost of extremely long recovery time.