An incremental algorithm for computing ranked full disjunctions

Sara Cohen*, Yehoshua Sagiv

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The full disjunction is a variation of the join operator that maximally combines tuples from connected relations, while preserving all information in the relations. The full disjunction can be seen as a natural extension of the binary outerjoin operator to an arbitrary number of relations and is a useful operator for information integration. This paper presents the algorithm IncrementalFD for computing the full disjunction of a set of relations. IncrementalFD improves upon previous algorithms for computing the full disjunction in four ways. First, it has a lower total runtime when computing the full result and a lower runtime when computing only k tuples of the result, for any constant k. Second, for a natural class of ranking functions, IncrementalFD can be adapted to return tuples in ranking order. Third, a variation of IncrementalFD can be used to return approximate full disjunctions (which contain maximal approximately join consistent tuples). Fourth, IncrementalFD can be adapted to have a block-based execution, instead of a tuple-based execution.

Original languageAmerican English
Pages (from-to)648-668
Number of pages21
JournalJournal of Computer and System Sciences
Volume73
Issue number4
DOIs
StatePublished - Jun 2007
Externally publishedYes

Bibliographical note

Funding Information:
* Corresponding author. E-mail addresses: [email protected] (S. Cohen), [email protected] (Y. Sagiv). URL: http://iew3.technion.ac.il/~sarac (S. Cohen). 1 The author was partially supported by Israel Science Foundation (Grant 1032/05). 2 The author was partially supported by Israel Science Foundation (Grant 893/05).

Keywords

  • Approximate
  • Full disjunction
  • Incomplete information
  • Null values
  • Outer-join
  • Query processing
  • Ranking

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