Lazy-split B+-tree: a novel B+-tree index scheme for flash-based database systems


Flash memory is rapidly being deployed as a data storage medium for embedded systems and tablet computers due to its shock resistance, fast access, and low power consumption, etc. However, it has some intractable characteristics, such as erase-before-write, asymmetric read/write/erase speed, and a limited number of write/erase cycles. Due to these hardware limitations, magnetic disk-based systems and applications can hardly make full use of the advantages of flash memory when adopting it directly for storage. For example, the frequent changes of B-tree can degrade the performance and negatively influence the lifespan of flash memory. Most state-of-the-art studies on flash-aware index design focused mainly on buffer and storage mechanisms whereby they can obtain efficient I/Os to flash memory. In this paper, we identify the problems inherent in the related studies, and then introduce the concepts of lazy-split, modify-two-node, and semi-clean, which make possible the construction of a novel index solution, the Lazy-Split B+-tree (LSB+-tree). In detail, by their introduction, the first concept of LSB+-tree can efficiently reduce the number of node splits, the second can reduce the number of node modifications, and the last can make a further improvement on buffer space utilization and flash writes reduction.

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Correspondence to Tae-Sun Chung.

Additional information

The preliminary version of this paper titled “FlashB-Tree: A Novel B-Tree Index Scheme for Solid State Drives” was published in the proceedings of the ACM Research in Applied Computation Symposium (ACM RACS 2011), pages 50–55, ACM New York, NY, USA, Nov., 2011.

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Jin, R., Cho, HJ., Lee, SW. et al. Lazy-split B+-tree: a novel B+-tree index scheme for flash-based database systems. Des Autom Embed Syst 17, 167–191 (2013).

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  • B+-Tree
  • Splitting policy
  • Replacement algorithm
  • Index manager
  • Flash memory