Rank-aware query optimization

Ihab F. Ilyas, Rahul Shah, Walid G. Aref, Jeffrey Scott Vitter, Ahmed K. Elmagarmid

Research output: Contribution to journalConference article

82 Citations (Scopus)


Ranking is an important property that needs to be fully supported by current relational query engines. Recently, several rank-join query operators have been proposed based on rank aggregation algorithms. Rank-join operators progressively rank the join results while performing the join operation. The new operators have a direct impact on traditional query processing and optimization. We introduce a rank-aware query optimization framework that fully integrates rank-join operators into relational query engines. The framework is based on extending the System R dynamic programming algorithm in both enumeration and pruning. We define ranking as an interesting property that triggers the generation of rank-aware query plans. Unlike traditional join operators, optimizing for rank-join operators depends on estimating the input cardinality of these operators. We introduce a probabilistic model for estimating the input cardinality, and hence the cost of a rank-join operator. To our knowledge, this paper is the first effort in estimating the needed input size for optimal rank aggregation algorithms. Costing ranking plans, although challenging, is key to the full integration of rank-join operators in real-world query processing engines. We experimentally evaluate our framework by modifying the query optimizer of an open-source database management system. The experiments show the validity of our framework and the accuracy of the proposed estimation model.

Original languageEnglish
Pages (from-to)203-214
Number of pages12
JournalProceedings of the ACM SIGMOD International Conference on Management of Data
Publication statusPublished - 27 Jul 2004
EventProceedings of the ACM SIGMOD International Conference on Management of Data, SIGMOD 2004 - Paris, France
Duration: 13 Jun 200418 Jun 2004


ASJC Scopus subject areas

  • Software
  • Information Systems

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