W.Yan and P.Larson, Eager aggregation and lazy aggregation, Proc. 21st VLDB Conference, Zurich, 1995, pp 345-357. This article was processed using the L a T E X macro package with LLNCS style  Home/Search   Document Not in Database   Summary   Related Articles   Check

....ag=51 and ag=52. A further equivalence they give governs the removal of redundant group by operations: gc aggr [ a; b) j (c; d) gc aggr s] gc aggr [ a; b) j (c; d) s] provided FV (a; b) FV (c) and Phi is idempotent. This can be shown to be an instance of eq=1 above. Yan and Larson [19] examine the optimisation of decomposable aggregation functions over bags, where an aggregation function f is decomposable if there exist functions f 1 and f 2 such that f (s 1 Phi s 2 ) f 2 (f 1 s 1 ) f 1 s 2 ) They identify sum, max, min and count as decomposable and use combinations of ....

W.Yan and P.Larson, Eager aggregation and lazy aggregation, Proc. 21st VLDB Conference, Zurich, 1995, pp 345-357. This article was processed using the L a T E X macro package with LLNCS style

....the actions, but not the control. Definitional trees are a high level abstraction to specify or infer some aspects of the control. The problem of building definitional trees from rewrite systems has been addressed only marginally in Theorem 19. Some algorithms for this task are presented in [24]. We have shown the application definitional trees to two interesting classes of rewrite systems, one appropriate for sequential computations, the other for parallel ones. An application of our results to inherently sequential computations allows us to extend the expressive power of some ....

Yonggong Yan. Building definitional trees. Master's project, Portland State University, Portland, OR, March 1992. This article was processed using the L a T E X macro package with LLNCS style

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