Scalable Database Logging for Multicores

Abstract

Modern databases, guaranteeing atomicity and durability, store transaction logs in a volatile, central log buffer and then flush the log buffer to non-volatile storage by the write-ahead logging principle. Buffering logs in central log store has recently faced a severe multicore scalability problem, and log flushing has been challenged by synchronous I/O delay. We have designed and implemented a fast and scalable logging method, ELEDA, that can migrate a surge of transaction logs from volatile memory to stable storage without risking durable transaction atomicity. Our efficient implementation of ELEDA is enabled by a highly concurrent data structure, GRASSHOPPER, that eliminates a multicore scalability problem of centralized logging and enhances system utilization in the presence of synchronous I/O delay. We implemented ELEDA and plugged it to WiredTiger and Shore-MT by replacing their log managers. Our evaluation showed that ELEDA-based transaction systems improve performance up to 71 x, thus showing the applicability of ELEDA.