Design of Embedded Database Based on Hybrid Storage of PRAM and NAND Flash Memory

摘要

Andorid which is the popular smart phone OS uses a database system to manage its private data storage. Although the database system supports a powerful and lighteweight database engine, its performance is limited by a single storage media, NAND flash memory, and a single file system, YAFFS2. In this paper, we propose a new embedded database system based on hybrid storage of PRAM and NAND flash memory. Using the byte-level and in-place read/write capability of PRAM, we separately manage a journaling process of the database system. It increases the transaction speed and reduces the additional overhead caused by NAND flash memory. We implement our database system using SQLite and dual file systems (YAFFS2 and PRAMFS). Consequently, the proposed database system reduces the response time of the database transaction by 45% compared to the conventional database system. In addition, it mitigates the burden of NAND flash memory management. Moreover, previous database applications can be executed on the proposed system without any modification.