We give a method for improving the efficiency of condition evaluation during rule processing in active database systems. The method derives, from a rule condition, two new conditions that can be used in place of the original condition when a previous value (true or false) of the original condition is known. The derived conditions are generally more efficient to evaluate than the original condition because they are incremental—they replace references to entire database relations by references to delta relations, which typically are much smaller. Delta relations are accessible to rule conditions in almost all current active database systems, making this optimization broadly applicable. We describe an attribute grammar based approach that we have used to implement our condition rewriting technique. This work was partially performed while the authors were at the IBM Almaden Research Center, San Jose, CA. At Stanford this work was supported by the Anderson Faculty Scholar Fund and by equipment grants from Digital Equipment Corporation and IBM Corporation.
Using delta relations to optimize condition evaluation in active databases / Baralis, ELENA MARIA; Widom, J.. - STAMPA. - 985:(1995), pp. 292-308. (Intervento presentato al convegno Rules in Databases systems 2nd International Workshop, RIDS '95 tenutosi a September 25–27, 1995 nel Glyfada, Athens (GRC)) [10.1007/3-540-60365-4_134].
Using delta relations to optimize condition evaluation in active databases
BARALIS, ELENA MARIA;
1995
Abstract
We give a method for improving the efficiency of condition evaluation during rule processing in active database systems. The method derives, from a rule condition, two new conditions that can be used in place of the original condition when a previous value (true or false) of the original condition is known. The derived conditions are generally more efficient to evaluate than the original condition because they are incremental—they replace references to entire database relations by references to delta relations, which typically are much smaller. Delta relations are accessible to rule conditions in almost all current active database systems, making this optimization broadly applicable. We describe an attribute grammar based approach that we have used to implement our condition rewriting technique. This work was partially performed while the authors were at the IBM Almaden Research Center, San Jose, CA. At Stanford this work was supported by the Anderson Faculty Scholar Fund and by equipment grants from Digital Equipment Corporation and IBM Corporation.Pubblicazioni consigliate
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https://hdl.handle.net/11583/2500038
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