Soft Lists: A Native Index Structure for NOR-Flash-Based Embedded Devices

Abstract

Efficient data indexing is significant to embedded devices, because both CPU cycles and energy are very precious resources. Soft lists, a new index structure for embedded devices with NOR flash, are proposed. The challenge of data indexing over NOR flash is that data update and pointer update may recursively trigger each other. Our approach is to allow a bounded number of probes when a pointer is de-referenced. By this way update and garbage collection is largely simplified, because data can be moved around physical locations without invalidating any pointers. Even better, search with soft lists is very fast, because the probes provide opportunities of forward random skips. Soft lists are evaluated and compared against tree-based index, and soft lists are shown simple but efficient.