Page 230 - Kỷ yếu hội thảo khoa học lần thứ 12 - Công nghệ thông tin và Ứng dụng trong các lĩnh vực (CITA 2023)

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A Buffer Based Scheme for SQLite on

NAND Flash Memory

1
2
VanPhi Ho , VanDai Tran , KimTrong Le
1
1 Computer Science Department, VKU
2 Computer Technology Department, VKU
{hvphi, tvdai, lktrong}@vku.udn.vn

Abstract. Recently, SQLite is the popular database on smart phone which uses
NAND flash memory to store data. Although SQLite is a lightweight and
powerful database engine and NAND flash memory is very fast, the performance
of SQLite is downgraded by physical limitation of flash memory such as
erase-before-write characteristic. Whenever updating data, SQLite has to create
or write back up data to a file called Journal file. This causes a lot of flash memory
operations leading to reduction of overall performance of SQLite. To address this
problem, this study introduces a buffer based scheme for SQLite on flash memory
by using FRAM, called BBS. BBS can minimize the overhead by deploying the
hybrid storage of FRAM and NAND flash memory. The experimental results
show that BBS yields a good performance and improves the reliability.

Keywords: SQLite, flash memory, FRAM, Smart phone database.

1 Introduction

Flash memory [1-3] has been widely used because it has many positive features such
as high-speed access, low power consumption, small size and high reliability. Besides
these advantages, it has some downsides including erase-before-write, limited life
cycle. To help hosts access data stored on the flash memory as accessing disk drives,
a module called Flash Translation Layer (FTL) [2] is used to process the logical-to-
physical address mapping between the host and flash memory. The FTL has two main
features: address mapping and garbage collection. To date, some FTL algorithms have
been proposed to limit the physical limitation characteristics and improve the overall
performance of flash memory.
Despite the fact that performance of a flash memory has been enhanced by using
FTL algorithms, it may encounter performance degradation problems when writing
data directly because the overwrite operations on flash memory frequently occur. To
address this problem, we propose a new buffer based scheme for SQLite on flash
memory, called BBS. The BBS deploys the logging and recovery policies by using
an FRAM[4] combining with the original flash memory. Whenever data is written or
updated, the BBS writes the data to FRAM to avoid losing data, and then, the data is
written to the flash memory as soon as the FRAM is full. If the system reboots after a

CITA 2023 ISBN: 978-604-80-8083-9