inObject - Oriented and Object - Relational Databases

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 evaluation plans and devise some new ones. These alternative plans are primarily based on anti-semijoin, division, generalized grouping with count aggregation, and set diierence. In order to evaluate the quality of the many diierent evaluation plans a thorough performance analysis on some sample database conngurations was carried out. The quantitative analysis reveals thattif applicableethe anti-semijoin-based plans are superior to all the other alternatives, even if we employ the most sophisticated division algorithms. Furthermore, exploiting object-oriented features, anti-semijoin plans can be derived even when this is not possible in the relational context.