Klaus Peithner

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We investigate the optimization and evaluation of queries with universal quantification in the context of the object-oriented and object-relational data models. The queries are classified into 16 categories depending on the variables referenced in the so-called range and quantifier predicates. For the three most important classes we enumerate the known(More)
In this work, we propose and assess a technique called <italic>bypass processing</italic> for optimizing the evaluation of disjunctive queries with expensive predicates. The technique is particularly useful for optimizing selection predicates that contain terms whose evaluation costs vary tremendously; e.g., the evaluation of a nested subquery or the(More)
We investigate the optimization and evaluation of queries with universal quan-tiication in the context of the object-oriented and object-relational data models. The queries are classiied into 16 categories depending on the variables referenced in the so-called range and quantiier predicates. For the three most important classes we enumerate the known query(More)
Adopting the blackboard architecture from the area of Arti cial Intelligence, a novel kind of optimizer enabling two desirable ideas will be proposed. Firstly, using such a well-structured approach backpropagation of the optimized queries allows an evolutionary improvement of (crucial) parts of the optimizer. Secondly, the A search strategy can be applied(More)
ÐIt is striking that the optimization of disjunctive queriesÐi.e., those which contain at least one or-connective in the query predicateÐhas been vastly neglected in the literature, as well as in commercial systems. In this paper, we propose a novel technique, called bypass processing, for evaluating such disjunctive queries. The bypass processing technique(More)
The bypass technique, which was formerly restricted to selections only KMPS94], is extended to join operations. Analogous to the selection case, the join operator may generate two output streams|the join result and its complement|whose subsequent operator sequence is optimized individually. By extending the bypass technique to joins, several problems have(More)
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