Efficient Online Index Maintenance for SSD-based Information Retrieval Systems

Solid state disks (SSDs) can potentially eliminate the I/O bottleneck for many conventional applications. However, they have a very unique characteristic of erase-before-write, which probably makes existing index maintenance methods inapplicable to SSDs. In this paper, we propose Hybrid Merge, a new online index maintenance strategy for information retrieval systems, which applies SSDs instead of hard disk drives (HDDs) to store inverted indexes. We analyze the existing indexing methods through experiments, and design a new merge-based indexing method with no random writes. We try to take the full advantage of the SSD's fast random reads to overcome the defects of existing methods. Experimental results show that the proposed method improves indexing and query performance with extremely low write traffic compare to existing approaches.