GRAIL: Scalable reachability index for large graphs

Hilmi Yildirim, Vineet Chaoji, Mohammed J. Zaki

Research output: Chapter in Book/Report/Conference proceedingChapter

85 Citations (Scopus)


Given a large directed graph, rapidly answering reachability queries between source and target nodes is an important problem. Existing methods for reachability trade-off indexing time and space versus query time performance. However, the biggest limitation of existing methods is that they simply do not scale to very large real-world graphs. We present a very simple, but scalable reachability index, called GRAIL, that is based on the idea of randomized interval labeling, and that can effectively handle very large graphs. Based on an extensive set of experiments, we show that while more sophisticated methods work better on small graphs, GRAIL is the only index that can scale to millions of nodes and edges. GRAIL has linear indexing time and space, and the query time ranges from constant time to being linear in the graph order and size.

Original languageEnglish
Title of host publicationProceedings of the VLDB Endowment
Number of pages9
Publication statusPublished - Sep 2010
Externally publishedYes


ASJC Scopus subject areas

  • Computer Science (miscellaneous)
  • Computer Science(all)

Cite this

Yildirim, H., Chaoji, V., & Zaki, M. J. (2010). GRAIL: Scalable reachability index for large graphs. In Proceedings of the VLDB Endowment (1 ed., Vol. 3, pp. 276-284)