A log-structured buffer for database systems using non-volatile memory.

Emerging next-generation non-volatile memory (NVM) technologies, including PCM and STT-MRAM, provide low latency, high bandwidth, non-volatility, and high capacity. Recently, NVM has drawn much attention from the database community to improve transaction processing (e.g., write-ahead logging). As a complement to existing work, we investigate NVM for atomic page updates in database systems. Atomic page update is required for consistent recovery, and database systems generally use redundant writes to support atomic page update (e.g., doublewrite buffer in MySQL/InnoDB). However, redundant writes negatively affect the database and lifetime of storage devices (e.g., flash-based SSD). In this paper, we present LSBM, a log-structured buffer manager which updates pages atomically and efficiently using NVM. LSBM updates pages in an out-of-place manner to achieve atomicity and performs page buffering to improve performance. LSBM also reclaims the buffered pages on the fly to reduce the write traffic to storage. We implement LSBM using an NVDIMM as NVM and ported it to MySQL/InnoDB. The experimental results demonstrate that LSBM improves database performance and reduces write traffic on OLTP workloads.