Full Outer Join Optimization Techniques in Integration Information Systems
Domenico Beneventano, Sonia Bergamaschi, Carlos Rodrigue, Nana Mbinkeu · 2006
In Integration Information Systems data fusion, i.e. the merging of multiple tuples about the same real world object coming from different sources into a consistent and homogeneous set is often ignored [5]. The full outer join operator is a good candidate in today’s integrating information systems, to perform data fusion [1, 6]. The problem is that full outer join queries are very expensive, especially in a distributed environment as the one of mediator/integration systems. Database optimizers take full advantage of associativity and commutativity properties of join to implement efficient and powerful optimizations on join queries; however, only limited optimization is performed on full outer join [6]. This paper reports the description of work-inprogress about query optimization techniques for full outer join queries developed in the context of the MOMIS/SEWASIE Integration System. 1