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Abstract : |
Many declarative query languages for object-oriented (oo) databases allow nested subqueries. This paper contains a complete classification of oo nested queries and appropriate unnesting optimization strategies based on algebraic rewriting. We adapt some known relational techniques and introduce new ones that use and are concerned with features specific to object-oriented queries. In particular, we introduce two new and powerful grouping operators which will form the basis for our unnesting techniques. Keywords: Query optimization, Object Oriented Databases., |
