Efficient Update of Indexes for Dynamically Changing Web Documents

  • Authors:

  • Lipyeow Lim;Min Wang;Sriram Padmanabhan;Jeffrey Scott Vitter;Ramesh Agarwal

  • Affiliations:

  • IBM T. J. Watson Research Ctr., Hawthorne, USA 10532;IBM T. J. Watson Research Ctr., Hawthorne, USA 10532;IBM Silicon Valley Lab., San Jose, USA 95141;Purdue University, West Lafayette, USA 47907;IBM Almaden Research Ctr., San Jose, USA 95120-6099

  • Venue:
  • World Wide Web
  • Year:
  • 2007

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Abstract

Recent work on incremental crawling has enabled the indexed document collection of a search engine to be more synchronized with the changing World Wide Web. However, this synchronized collection is not immediately searchable, because the keyword index is rebuilt from scratch less frequently than the collection can be refreshed. An inverted index is usually used to index documents crawled from the web. Complete index rebuild at high frequency is expensive. Previous work on incremental inverted index updates have been restricted to adding and removing documents. Updating the inverted index for previously indexed documents that have changed has not been addressed. In this paper, we propose an efficient method to update the inverted index for previously indexed documents whose contents have changed. Our method uses the idea of landmarks together with the diff algorithm to significantly reduce the number of postings in the inverted index that need to be updated. Our experiments verify that our landmark-diff method results in significant savings in the number of update operations on the inverted index.