Flash memory is being rapidly deployed as data storage for mobile devices. Flash memory offers many advantages over hard disk, and considering its rapid technical improvement both in capacity and speed, it will have competitive advantage over minidrive under 100 Gbytes within a few years. As the applications in hand held devices become large, complex, and more data-intensive, they require database technology. However, flash memory has three distinct characteristics that make today’s disk-based database technology unsuitable. In this article, we first review the characteristics of the flash memory. Then we identify several key issues in the architecture of a flash-based database system that require careful re-examinations.