Department of Computer Science and EngineeringEmerging byte-addressable persistent memory (PM) will be effective to improve the performance of computer system by reducing the redundant write operations. Traditional database management system uses recovery techniques to prevent data loss. The techniques copy the entire page into the block device storage several times for one insertion, so the amount of I/O is not negligible.
In this work, we consider PM as main memory. Then, the durability of data in the buffer cache is ensured. To guarantee consistency, we exploit slotted page structure which is commonly used in database systems. We revisit that the slot header, which stores the metadata of the page in the slotted page structure, can act like a commit mark in the persistent database buffer cache.
We then present two novel database management schemes using persistent buffer cache and slotted page. In-place commit scheme updates the page atomically using hardware transactional memory. It doesn't make any other copies and has optimal performance. Slot header logging scheme is needed for the case of updating pages more than one. Unlike the existing logging technique, slot header logging reduces the write operations by logging only commit mark.
We implemented these schemes in SQLite and evaluate the performance compared with NVWAL, which is the state-of-the-art scheme. Our experiments show that in-place commit scheme needs only 3 cache line flush instructions for one insertion and slot header logging scheme reduces logging overhead at least 1/4.ope
