Spatial queries with two kNN predicates

Ahmed M. Aly, Walid G. Aref, Mourad Ouzzani

Research output: Chapter in Book/Report/Conference proceedingChapter

11 Citations (Scopus)


The widespread use of location-aware devices has led to countless location-based services in which a user query can be arbitrarily complex, i.e., one that embeds multiple spatial selection and join predicates. Amongst these predicates, the k-Nearest-Neighbor (kNN) predicate stands as one of the most important and widely used predicates. Unlike related research, this paper goes beyond the optimization of queries with single kNN predicates, and shows how queries with two kNN predicates can be optimized. In particular, the paper addresses the optimization of queries with: (i) two kNN-select predicates, (ii) two kNN-join predicates, and (iii) one kNN-join predicate and one kNN-select predicate. For each type of queries, conceptually correct query evaluation plans (QEPs) and new algorithms that optimize the query execution time are presented. Experimental results demonstrate that the proposed algorithms outperform the conceptually correct QEPs by orders of magnitude.

Original languageEnglish
Title of host publicationProceedings of the VLDB Endowment
Number of pages12
Publication statusPublished - Jul 2012


ASJC Scopus subject areas

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

Cite this

Aly, A. M., Aref, W. G., & Ouzzani, M. (2012). Spatial queries with two kNN predicates. In Proceedings of the VLDB Endowment (11 ed., Vol. 5, pp. 1100-1111)