Cache-oblivious range reporting with optimal queries requires superlinear space

  • Authors:
  • Peyman Afshani;Chris Hamilton;Norbert Zeh

  • Affiliations:
  • University of Aarhus, Aarhus, Denmark;Dalhousie University, Halifax, NS, Canada;Dalhousie University, Halifax, NS, Canada

  • Venue:
  • Proceedings of the twenty-fifth annual symposium on Computational geometry
  • Year:
  • 2009

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Abstract

We consider a number of range reporting problems in two and three dimensions and prove lower bounds on the amount of space required by any cache-oblivious data structure for these problems that achieves an optimal query bound of O(logBN + K/B) block transfers in the worst case, where K is the size of the query output. The problems we study are three-sided range reporting, 3-d dominance reporting, and 3-d halfspace range reporting. We prove that, in order to achieve the above query bound or even a bound of O((logB N)c (1 + K/B)), for any constant c 0, the structure has to use Ohmega(N (log log N)ε) space, where ε 0 is a constant that depends on c and on the constant hidden in the big-Oh notation of the query bound. Our result has a number of interesting consequences. The first one is a new type of separation between the I/O model and the cache-oblivious model, as I/O-efficient data structures with the optimal query bound and using linear or O(N logAST N) space are known for the above problems. The second consequence is the non-existence of a linear-space cache-oblivious persistent B-tree with worst-case optimal 1-d range reporting queries.