A Novel B-Tree Index with Cascade Memory Nodes for Improving Sequential Write Performance on Flash Storage Devices

Abstract

Flash storage devices such as solid-state drives and multimedia cards have been widely used in various applications because of their fast access speed, low power consumption, and high reliability. They consist of NAND flash memories that perform slow block erasures before overwriting data on a prewritten page. This characteristic can lead to performance degradation when applying the original B-tree on the flash storage device without any changes. Although various B-trees have been proposed for flash memory, they still require many flash operations that degrade overall performance. To address the problem, we propose a novel B-tree index structure that reduces the number of write operations and improves the sequential writes by employing cascade memory nodes. The proposed B-tree index structure delays the updates for the modified B-tree nodes and later performs batch writes in a cascade manner. Also, when records with continuous key values are sequentially inserted, the proposed B-tree index structure does not split the leaf node so that it improves write throughput and page utilization. Through mathematical analysis and experimental results, we show that the proposed B-tree index structure always yields better performance than existing techniques.