An incremental algorithm for computing ranked full disjunctions

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 three 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 returns tuples in ranking order. Third, IncrementalFD can be adapted to have a block-based execution, instead of a tuple-based execution.

• Type: Conference
• Year: 2005
• Where: PODS
• Authors: Sara Cohen, Yehoshua Sagiv
• Keywords: Binary Outerjoin Operator, Connected Relations, Database, Disjunction, PODS 2005