Klaus Peithner

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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)
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)
Adopting the blackboard architecture from the area of Articial 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 3 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)
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)
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)
The eld of object-oriented databases is suering from the lack of a|widely agreed upon|formal model. In this paper we develop the basics of a formal model for an object-oriented data model (kernel). The formalization is based on dynamic logic: combining many-sorted algebras with states and state transitions. The many-sorted algebras are utilized to model the(More)
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